# Comprehensive Catalogue of the Overall Best Distances and Properties of 402
Galactic Novae

Bradley E. Schaefer1,
1Department of Physics and Astronomy, Louisiana State University, Baton Rouge,
Louisiana, 70820, USA
E-mail<EMAIL_ADDRESS>
###### Abstract

I derive the overall best distances for all 402 known galactic novae, and I
collect their many properties. The centrepiece is the 74 novae with accurate
parallaxes from the new Gaia data release. For the needed priors, I have
collected 171 distances based on old methods (including expansion parallaxes
and extinction distances). Further, I have collected the V-magnitudes at peak
and the extinction measures, so as to produce absolute magnitudes at peak and
then derive a crude distance as a prior. Further, I have recognized that 41
per cent of the known novae are concentrated in the bulge, with 68 per cent of
these $<$5.4$\degr$ from the galactic centre, so the 165 bulge novae must have
distances of 8000$\pm$750 parsecs. Putting this all together, I have derived
distances to all 402 novae, of which 220 have distances to an accuracy of
better than 30 per cent. I find that the disc novae have an exponential scale
height of 140$\pm$10 pc. The average peak absolute V-magnitude is -7.45, with
an RMS scatter of 1.33 mag. These peak luminosities are significantly
correlated with the decline rate ($t_{3}$ in days) as
$M_{V,peak}=-7.6+1.5\log(t_{3}/30)$. The huge scatter about this relation
masks the correlation in many smaller datasets, and makes this relation
useless for physical models. The bulge novae are indistinguishable from the
disc novae in all properties, except that the novae with red giant companion
stars have a strong preference for residing in the bulge population.

###### keywords:

stars: variables – stars: novae, cataclysmic variables

††pubyear: 2021††pagerange: Comprehensive Catalogue of the Overall Best
Distances and Properties of 402 Galactic Novae–References

##  1 INTRODUCTION

Since the earliest days, astrophysics has had the difficult primary task of
measuring the distances to objects of all classes. For the classical
novae111The classical novae (CNe) are cataclysmic variables (CVs) in binaries
with a relatively ordinary companion star spilling mass into an accretion disc
around a white dwarf, which display runaway thermonuclear explosions on the
surface of the white dwarf (Warner 2008). These nova eruptions have outburst
amplitudes $\gtrsim$8 mags, rise times of days to weeks, and durations of
weeks to many months (Payne-Gaposchkin 1964). An important class of CNe is the
recurrent novae (RNe), which are ordinary novae that happen to have recurrence
time-scales faster than a century (Schaefer 2010)., measuring accurate
distances has also long been an enterprise of the highest importance. Starting
around the 1920s, novae were being distinguished as a separate class, distinct
from other transients, with the nova distances bound up in the debates over
the separate existence of galaxies as well as the separate existence of
supernovae. Starting soon after the 1901 eruption of GK Per, a small number of
novae had measured distances from the expansion parallax method, wherein the
expanding nova shell had some vague edge matched to some poorly-defined radial
velocity from an eruption spectrum. For many decades, the distances to
individual novae were few and unreliable, with the best being the relative
distances for the novae seen in globular clusters, the Magellanic Clouds, and
the Andromeda Galaxy. Even by the time of Payne-Gaposchkin’s great treatise in
1964, little else was known.

Starting around the 1980s, a wide variety of distances for individual novae
were put forth, all with poor reliability. A common on-going analysis of new
novae would use some measure of the interstellar extinction, somehow
calibrated, to derive distances, but such measures were uniformly poor and the
calibrations had huge uncertainties. And measures of the observed peak
magnitudes (and related quantities) were used with a wide variety of poorly
calibrated correlations to get distances, but even the calibration novae
displayed huge scatter, so any pretense for accuracy was not justified
(Schaefer 2018). The best of the measures were from expansion parallaxes,
while an impressive paper by Downes & Duerbeck (2000) used the Hubble Space
Telescope (HST) to image 30 novae, collect all prior shell size data, and came
up with 29 expansion parallax distances. Around this time, attempts were made
to use novae to independently derive the distances to nearby galaxies and the
Hubble Constant (Jacoby et al. 1992).

Starting around a decade ago, newly measured nova distances were being
published with substantially better reliability. For the extinction distances,
Özdönmez et al. (2018) systematically collected nova extinction measures and
made good averages, and then used infrared sky surveys showing the tip of the
red giant branch stars to provide a good calibration of the extinction as a
function of distance along sightlines close to each nova. Parallaxes have
always been the best method to get reliable distances to stars, and nova
parallaxes started to be produced, first for 4 novae with the HST by Harrison
et al. (2013), then 3 novae with the first data release of Gaia (Ramsay et al.
2017), then I used the Gaia Data Release number 2 (DR2) parallaxes to report
41 accurate nova distances (Schaefer 2018).

The natural follow-up to the DR2 list of nova distances is to use the Gaia
third data release (DR3) to construct a set of improved nova distance for many
more novae. This is a primary goal of this paper. The new Gaia data provides
good-accuracy distances to 74 novae. In addition, DR3 provides low-accuracy
distances (often really just lower limits) for 121 novae. To realize these
distances, the correct Bayesian calculations require the use of prior
information, with such never having been assembled previously for any set of
novae. This prior information needs the assembly of all prior published
distances from all the many old methods found throughout the literature.
Further, the prior information needs the magnitudes and extinctions for the
many Gaia novae. So the correct use of the good and the poor Gaia parallaxes
requires a large scale data mining program.

Once we have the idea of making a large catalog of the best distances for the
Gaia novae, a natural extension is to get the best distances for $\it all$
known galactic novae. For the novae not in Gaia DR3, all we have is a
collection of non-parallax data. For roughly a third of the novae, the only
useful information is the galactic position. For the bulge novae, this turns
out to give accurate and reliable distances. For the disc novae, the position
alone can provide distance constraints with the uncertainty of order 3$\times$
from the central estimate, and that is adequate for many purposes. So my
program is extended to provide the best possible distances for all galactic
novae.

The first step of the program is to construct a complete census of known
galactic novae for peaks with all times before middle 2022. This list was
constructed from partial lists in Duerbeck (1987), the Catalog and Atlas of
Cataclysmic Variables (CVCat, Downes et al. 2001, updated to 2005), the
International Variable Star Index222https://www.aavso.org/vsx/ (VSX) of the
American Association of Variable Star Observers, and the up-to-date
list333https://asd.gsfc.nasa.gov/Koji.Mukai/novae/novae.html of K. Mukai (NASA
HEASARC). In most cases, the status as a nova is clear from the light curve
and spectra, however, roughly a dozen systems are poorly observed so that the
nova status is questionable, and for this I have followed the always excellent
judgement of H. Duerbeck in his very useful catalog (Duerbeck 1987). For
inclusion in my list, I required good evidence that the transient was indeed a
classical nova. My list does not include the red novae (like V838 Mon and
V1309 Sco), the symbiotic novae (like PU Vul and V1016 Cyg), the X-ray novae
(like V404 Cyg and V616 Mon), nor systems that show only dwarf nova events
(like WX Cet and WZ Sge), because these eruptions are all morphologically
greatly different, the systems have different evolution, and are dominated by
different mechanisms. In the end, I have 402 systems that are confidently
galactic novae.

##  2 NOVA DISTANCES FROM ALL THE OLD METHODS

The olden standard for nova distances has been the expansion parallax.
Schaefer (2018) used Gaia DR2 parallaxes and found that the real accuracy has
a one-sigma error bar of 0.95 mag in the distance modulus. Here, I have
collected 38 expansion parallax distances as previously collected in Schaefer
(2018) and Özdönmez et al. (2018).

A traditional astronomy method for getting nova distances is to somehow
measure the extinction from the intervening interstellar medium (ISM), then to
calibrate the extinction as a function of distance along the line of sight to
the nova. The olden extinction distances were always poor. A useful new tool
has been the reddening maps showing $E(B-V)$ for the entire line of sight
through our galaxy, all with high accuracy for lines-of-sight within 5 arc-
minutes of any target, as based on the far-infrared dust emission (Schlafly &
Finkbeiner 2011). Recently, a good advance has been made by Özdönmez et al.
(2018), where the extinction as a function of distance is calibrated from the
brightness and color of red clump stars observed by several deep infrared sky
surveys. Özdönmez et al. reports on 81 reddening distances, including 29 lower
limits on distances. Schaefer (2018) found that these reddening-distances have
a one-sigma uncertainty of 1.01 mag in the distance moduli.

Here, I introduce another method based on extinction. The idea is that the
total extinction throughout the Milky Way along every line of sight is known
from infrared mapping (Schlafly & Finkbeiner 2011), so for systems with
substantially less than the maximum, we can quantitatively estimate the nova
distance. For example, V4742 Sgr has the maximum possible extinction of 5.65
mag, while its measured $E(B-V)$ is 1.5$\pm$0.2. With the majority of the
line-of-sight extinction occurring within the region around the centre of our
galaxy, V4742 Sgr must be substantially closer than 8000 pc. To be
quantitative, I have modeled the Milky Way dust as the usual axisymmetric
exponential disc, with a scale height of 100 pc out of the galactic plane, and
with a scale length of 3200 pc in its galactocentric radius distribution (Li
et a. 2018). From an integral within this model, I calculate the dust column
density as a function of distance from Earth, and scale this by the maximum
$E(B-V)$ for the entire column through our Milky Way. The observed extinction
can then be matched to distance, and this can be converted to a distance
modulus. For V4742 Sgr, the observed extinction corresponds to a distance of
3120$\pm$380 pc, or a distance modulus of $\mu$=12.47$\pm$0.26. The formal
error bars are likely much too small, partly because the real dust in our
galaxy is much more clumpy than in the standard model. I will adopt the same
one-sigma uncertainty of 1.01 mag, as in the previous paragraph. The results
from this method are superseded by the better calibration of Özdönmez et al.
(2018). The only novae for which this method provides useful constraints are
KY Sgr, V4742 Sgr, V4744 Sgr, V5586 Sgr, and V1662 Sco.

A physics method for nova distances is to get a blackbody distance to the
companion stars. I have collected 7 blackbody distances from Schaefer (2010),
Salazar et al. (2017), and Shara et al. (2017a).

Another physics method is to model the eruption light curve of an individual
nova, scale the time to a universal law, so as to derive the peak absolute
magnitude, which then gives the distance modulus. I. Hachisu (University of
Tokyo) and M. Kato (Keio University) are the only modelers with this method,
from which I have collected 68 nova distances as reported in Hachisu & Kato
(2021) and references therein. Schaefer (2018) found that these measures have
a one-sigma uncertainty of 0.76 mag in the distance moduli.

The HST has been able to measure good parallaxes for four of the nearest and
brightest novae; V603 Aql, DQ Her, GK Per, and RR Pic (Harrison et al. 2013).
Schaefer (2018) found these four measures to be substantially poorer than the
quoted error bars, with the average one-sigma uncertainty being 0.37 mag in
the distance moduli.

A unique method for measuring a nova distance has been presented by Sokolowski
et al. (2013) for the RN T Pyx, wherein the light echo as reflected by the
previously ejected nova shells is used similarly to the expansion parallax.

Two novae are known to appear inside galactic globular clusters, with the nova
positions being sufficiently close to the cores so that the membership in the
cluster is not in any doubt. The old nova T Sco is in the globular M80, while
Nova 1938 Oph is in M14. The distances to the host globular clusters are taken
from the Gaia EDR3 parallaxes for over 600 member stars (Vasiliev & Baumgardt
2021).

These distances are collected into Table 1. The first column gives the nova
designation, with the novae listed in the standard order as in the General
Catalog of Variable Stars (GCVS). The second column gives the reported old
distances, in parsecs. The third column gives the associated distance modulus
and its assigned one-sigma uncertainty. The last column gives the method for
the old distance, with 38 expansion parallaxes, 87 distances and limits based
on extinction, 7 blackbody distances from the companions, 32 distances based
on the physics models of Hachisu & Kato, 4 parallax distances from $HST$, 1
light echo distance for T Pyx, and 2 distances for the host globular clusters.
For all of the old methods, I have a total of 171 distances, of which 29 are
lower limits on the distance.

Table 1: Compilation of Nova Distances from Old Methods (full table with 171 novae is in on-line supplementary material) Nova | D (pc) |  $\mu_{old}$ (mag) | Method
---|---|---|---
OS And | 7300 | 14.32 $\pm$ 0.76 | Model
CI Aql | 3900 | 12.96 $\pm$ 1.01 | Extinction
V500 Aql | 5900 | 13.85 $\pm$ 0.95 | Expansion
V603 Aql | 249 | 6.98 $\pm$ 0.37 |  $HST$ $\varpi$
V1229 Aql | 2400 | 11.90 $\pm$ 0.95 | Expansion
… |  |  |
PW Vul | 1800 | 11.28 $\pm$ 0.95 | Expansion
QU Vul | 3140 | 12.48 $\pm$ 0.95 | Expansion
QV Vul | 2700 | 12.16 $\pm$ 0.95 | Expansion
V458 Vul |  $>$ 6000 |  $>$ 13.89 $\pm$ 1.01 | Extinction
V459 Vul | 3800 | 12.90 $\pm$ 0.76 | Model

##  3 DISTANCES BASED ON THE PEAK MAGNITUDES

Despite the historical confusions, there is good information on nova distances
from the peak magnitudes, and this method can be applied to most old novae.
Indeed, for many novae, the peak magnitude provides the only specific
information on $D$. Even for those novae with Gaia parallaxes, the distances
from the peak magnitudes will form the primary basis for the priors as used in
the Bayesian calculation of the parallax-distances.

For my plan of getting the best distance information for all 402 galactic
novae, I need to collect the peak magnitudes and extinctions for all the novae
that were observed at maximum. More specifically, I need the observed peak
$V$-band magnitude, $V_{peak}$, as well as the color excess, $E(B-V)$. These
will be used to calculate the distance modulus, $\mu_{peak}$.

In bureaucratic mode, we could just look up the peak magnitudes in various
catalogs, but such would be poor for the majority of the novae. A primary
problem is that the usual tabulations often are listing only the maximum
observed brightness, which might or might not be at the real peak, or worse
will list some speculative peak magnitude based on extrapolation. Another big
problem is that the peak magnitudes are often in a wide variety of band passes
other than $V$-band, with the applicable band being often unstated, whereas
some correction is needed to get to $V_{peak}$. These problems can be
confidently solved for over a hundred of the brightest novae, with these being
well observed and reported in the literature. The best source is Strope,
Schaefer, & Henden (2010) for the 93 all-time (before 2010) best observed
novae, because this work went back and pulled out all the light curves, from
all the published literature, from the entire AAVSO database, plus extensive
measures of my own from the Harvard plates. Another reliable source is
Duerbeck’s catalog (Duerbeck 1987) for all novae up until 1987, as he also
went back to the entire literature plus going back to the original
photographic plates of old, and his evaluations are excellent. Another
reliable source is C. Payne-Gaposchkin’s great treatise (Payne-Gaposchkin
1964), also with references to the full literature and a deep knowledge of the
Harvard plates. Even with these excellent compilations, the majority of the
novae still have either unlisted or questionable peak magnitudes. At this
time, the only way to produce reliable measures of $V_{peak}$ or its limit is
to go through the entire literature and AAVSO database exhaustively for
roughly 300 novae.

To get a useable distance modulus, we also need a reliable measure of
extinction. For this, the literature contains useful measures of $E(B-V)$, or
its equivalent, for only the brighter novae, and these are often contradictory
and always scattered by much more than the quoted error bars. Özdönmez et al.
(2018) compiled an exhaustive and excellent summary of the scattered
literature to make judicious evaluations for the $E(B-V)$ of 178 galactic
novae. This provides the foundation for my tabulation of $E(B-V)$. But we
still need some sort of an estimate for the remaining 224 galactic novae. For
this, a wonderful tool is the all-sky catalog of $E(B-V)$ through the entire
line of sight through our Milky Way galaxy (Schlafly & Finkbeiner 2011). This
serves to put an approximate-but-strict upper limit on $E(B-V)$. For some
novae, this upper limit serves as an adequate constraint, while many other of
the faintest novae away from the galactic plane must have their extinction
close to the limit (as the nova is certainly far past all galactic dust). For
the roughly 200 novae without useful limits from Özdönmez or Schlafly &
Finkbeiner, the only solution is to go through the literature and data for
effective evidence on the extinction. I have also pulled out good measures of
extinction by extracting the $V_{peak}$ and $B_{peak}$ from the magnitudes
scattered through the literature (see below).

While doing these exhausting and exhaustive searches of the literature and
databases, I have also tabulated the best information on a variety of other
nova properties. From my new light curve compilations, I have classified 265
light curves into the classes S, P, O, C, D, J, and F (Strope et al. 2010).
These light curve classes are strongly correlated with a variety of nova
properties. From the literature (primarily the Strope catalog and the Duerbeck
catalog) and from my own compilations of the light curves, I have measured
both $t_{2}$ and $t_{3}$ (the number of days for the nova light curve to
decline from peak magnitude by 2 and by 3 magnitudes). From all this, I have
only been able to extract 262 and 252 reliable measures of $t_{2}$ and $t_{3}$
respectively. I have also compiled lists of the spectral classifications for
259 nova, with the classes being Fe II, He/N, and Hybrid, as well as whether
it is a Neon Novae. I have also compiled a list of the shell expansion
velocity for 216 galactic novae, as measured by the FWHM of the H$\alpha$
line. This measure changes substantially with the development over time, and
the literature often only reports the FWHM of other hydrogen lines or the FWZI
of the Balmer lines, so this compilation has inhomogeneities at perhaps the 30
per cent level. My list of spectral classes and FWHM values is just a large
extension of the list presented in Pagnotta & Schaefer (2014). Schaefer (2022)
has already compiled a list of the orbital periods for 156 galactic novae,
with this list including 49 newly discovered orbital periods and the list is
2$\times$ longer than previous lists. Finally, I have also compiled the
galactic coordinates for all 402 novae, mainly from the VSX database.

Importantly, I have been careful for distinguishing whether the true peak was
observed. For inclusion in my list of measured $V_{peak}$, I require some
suitable evidence that the brightest observed magnitude is close in time to
the real peak. This evidence is usually an observed rise to maximum, or a
useful closely-spaced pre-eruption limit, or a spectroscopic ‘age’. When
multiple measures on the night of peak are available, I use the nightly
average. When I determine that the nova light curve does not reliably
represent the true maximum, I list the $V_{peak}$ as a limit.

The light curves and the tabulated peak magnitudes are usually in the
$V$-band, however, 102 nova from before 1973 have only $B$-band light curves,
almost always based on the archival Harvard plates. The spectral sensitivity
of these plates is essentially identical to that of the Johnson $B$-band, so
there is no color-term for the reported magnitudes. The peak magnitudes for
novae are always in the bright regime, where the comparison stars are
accurately on the modern magnitude scale. So the magnitudes reported for the
Harvard plates (and the Sonneberg plates) are all reliably in the modern
$B$-band. For these novae, we must convert from $B_{peak}$ to $V_{peak}$ as

$V_{peak}=B_{peak}-E(B-V)-\langle(B-V)_{peak,0}\rangle.$ (1)

The last term is the intrinsic color at peak. This color is nearly a constant
from nova-to-nova, having to do with the temperature of the photosphere in the
expanding nova shell being determined by the ionization temperature of
hydrogen.

This intrinsic color at maximum has long been realized to be approximately 0.0
mag. The only systematic measure that I know of is from van den Bergh &
Younger (1987), who used 7 novae (after discarding two outliers) to get
$+$0.23 mag, with an RMS scatter of 0.16 mag. I can improve substantially on
this old value by using 24 nova with the uncertainty in the extinction of 0.10
mag or less, as listed in GCVS order in Table 2. The second column gives the
light curve class (‘LC’), with the point to be that the intrinsic color at
maximum light does not depend significantly on the class of the nova. The next
two columns give my measure of the observed $B-V$ at the time of peak light in
the $V$-band and my estimated $E(B-V)$ as based on methods not involving the
nova colors, both in units of magnitudes. The last column gives the derived
$(B-V)_{peak,0}$. The RMS scatter of the intrinsic colors (0.19 mag)
effectively equals the average uncertainty for all 24 novae (0.18 mag), which
means that the observed scatter is all measurement errors and the underlying
distribution is consistent with being a single constant. The average intrinsic
color is $\langle(B-V)_{peak,0}\rangle$=$+$0.11$\pm$0.04 mag.

Table 2: Intrinsic Color at Peak, $(B-V)_{peak,0}$ Nova | LC | $(B-V)_{peak}$ | $E(B-V)$ | $(B-V)_{peak,0}$
---|---|---|---|---
OS And | D | 0.44 $\pm$ 0.14 | 0.15 $\pm$ 0.05 | 0.29 $\pm$ 0.15
V705 Cas | D | 0.60 $\pm$ 0.14 | 0.41 $\pm$ 0.06 | 0.19 $\pm$ 0.15
V1065 Cen | P | 0.49 $\pm$ 0.28 | 0.47 $\pm$ 0.05 | 0.02 $\pm$ 0.28
FM Cir | J | 0.30 $\pm$ 0.28 | 0.23 $\pm$ 0.05 | 0.07 $\pm$ 0.28
V394 CrA | P | -0.20 $\pm$ 0.14 | 0.20 $\pm$ 0.10 | -0.40 $\pm$ 0.17
T CrB | S | 0.50 $\pm$ 0.14 | 0.10 $\pm$ 0.10 | 0.40 $\pm$ 0.17
V1500 Cyg | S | 0.64 $\pm$ 0.14 | 0.45 $\pm$ 0.07 | 0.19 $\pm$ 0.16
V1668 Cyg | S | 0.68 $\pm$ 0.14 | 0.38 $\pm$ 0.05 | 0.30 $\pm$ 0.15
V1974 Cyg | P | 0.50 $\pm$ 0.14 | 0.26 $\pm$ 0.03 | 0.24 $\pm$ 0.14
V2491 Cyg | C | 0.41 $\pm$ 0.14 | 0.23 $\pm$ 0.05 | 0.18 $\pm$ 0.15
V339 Del | PP | 0.25 $\pm$ 0.14 | 0.18 $\pm$ 0.04 | 0.07 $\pm$ 0.15
V408 Lup | J | 0.68 $\pm$ 0.14 | 0.40 $\pm$ 0.10 | 0.28 $\pm$ 0.17
T Pyx | P | 0.30 $\pm$ 0.14 | 0.25 $\pm$ 0.02 | 0.05 $\pm$ 0.14
V4739 Sgr | S | 0.55 $\pm$ 0.14 | 0.46 $\pm$ 0.04 | 0.09 $\pm$ 0.15
V5579 Sgr | D | 0.73 $\pm$ 0.14 | 0.72 $\pm$ 0.06 | 0.01 $\pm$ 0.15
V5583 Sgr | S | 0.42 $\pm$ 0.28 | 0.34 $\pm$ 0.10 | 0.08 $\pm$ 0.30
V5668 Sgr | D | 0.40 $\pm$ 0.14 | 0.21 $\pm$ 0.10 | 0.19 $\pm$ 0.17
V6594 Sgr | P | 0.36 $\pm$ 0.14 | 0.30 $\pm$ 0.05 | 0.06 $\pm$ 0.15
U Sco | PP | 0.30 $\pm$ 0.14 | 0.20 $\pm$ 0.10 | 0.10 $\pm$ 0.17
NR TrA | J | -0.08 $\pm$ 0.28 | 0.22 $\pm$ 0.05 | -0.30 $\pm$ 0.28
V382 Vel | S | 0.06 $\pm$ 0.14 | 0.12 $\pm$ 0.03 | -0.06 $\pm$ 0.14
LV Vul | S | 0.95 $\pm$ 0.14 | 0.57 $\pm$ 0.05 | 0.38 $\pm$ 0.15
QV Vul | D | 0.66 $\pm$ 0.14 | 0.40 $\pm$ 0.05 | 0.26 $\pm$ 0.15
V458 Vul | J | 0.55 $\pm$ 0.28 | 0.50 $\pm$ 0.05 | 0.05 $\pm$ 0.28

For novae that have well measured peaks in both the $B$ and $V$, equation (1)
can be turned around to get a good measure of the $E(B-V)$. This is useful for
the many faint novae that are too faint to have had any useful measure of the
extinction from spectroscopy.

My collected $V_{peak}$ and $E(B-V)$ values for all 402 galactic novae are
presented in Table 3. The first column is the nova in GCVS order. The next two
columns give the best $V_{peak}$ and $E(B-V)$ values.

To get the distance modulus, we also have to have an independent measure of
the absolute magnitude at peak, $M_{V,peak}$. Schaefer (2018) has already
demonstrated that the various historical calibrations are poor. So I do not
know of any means to produce the best peak absolute magnitude that is any
better than just taking the average. Schaefer (2018) used Gaia DR2 parallaxes
to find the average $M_{V,peak}$ is -7.0 mag, with a one-sigma scatter of 1.4
mag.

My values of $V_{peak}$ and $E(B-V)$ are combined with the adopted
$M_{V,peak}$ to produce a distance modulus, $\mu_{peak}$. To be specific,

$\mu_{peak}=V_{peak}-3.1E(B-V)-(-7.0).$ (2)

The uncertainties are calculated from the usual propagation of errors for each
of the terms. My derived $\mu_{peak}$ values are tabulated in the fourth
column of Table 3 for all 402 galactic novae.

The uncertainty on the distance modulus is always $\pm$1.4 mag or somewhat
larger, which is a reflection of the fact that we cannot independently know
the real luminosity of the nova with any good accuracy. This relatively poor
accuracy is still useful for some purposes, including distinguishing bulge
from disc novae. For many novae, this will be the only useful specific
information of their distances. These $V_{peak}$-distances will also provide
the prior information used in the Bayesian calculations from the Gaia
parallaxes. For the novae with accurate Gaia parallaxes, the
$V_{peak}$-distances will have little effect on the final range of distances.
For the majority of novae with relatively poor Gaia parallaxes, the
$V_{peak}$-distances will provide a prior that will force the result towards
the near or far side of the range allowed from the parallaxes.

Table 3: Distance Moduli from $V_{peak}$ With $M_{V,peak}$=$-$7.0$\pm$1.4 (full table with 402 novae is in on-line supplementary material) Nova |  $V_{peak}$ (mag) |  $E(B-V)$ (mag) |  $\mu_{peak}$ (mag)
---|---|---|---
OS And | 6.50 $\pm$ 0.10 | 0.15 $\pm$ 0.05 | 13.04 $\pm$ 1.41
CI Aql | 9.00 $\pm$ 0.10 | 0.85 $\pm$ 0.30 | 13.37 $\pm$ 1.68
DO Aql | 8.50 $\pm$ 0.10 | 0.29 $\pm$ 0.10 | 14.60 $\pm$ 1.44
EL Aql | 5.32 $\pm$ 0.18 | 0.97 $\pm$ 0.15 | 9.31 $\pm$ 1.49
EY Aql | 9.69 $\pm$ 0.54 | 1.10 $\pm$ 0.50 | 13.28 $\pm$ 2.16
… |  |  |
QV Vul | 7.10 $\pm$ 0.10 | 0.40 $\pm$ 0.05 | 12.86 $\pm$ 1.41
V458 Vul | 8.10 $\pm$ 0.20 | 0.50 $\pm$ 0.05 | 13.55 $\pm$ 1.42
V459 Vul | 7.60 $\pm$ 0.10 | 0.86 $\pm$ 0.12 | 11.93 $\pm$ 1.45
V569 Vul |  $<$16.3 $\pm$ 0.20 | 3.06 $\pm$ 0.50 |  $<$13.81 $\pm$ 2.10
V606 Vul | 10.10 $\pm$ 0.10 | 0.86 $\pm$ 0.20 | 14.43 $\pm$ 1.53

##  4 DISTANCES TO BULGE NOVAE

Figure 1: Galactic distribution for 402 novae. The nova distribution is the sum of a disc population (over all galactic longitudes and mostly within 10$\degr$ of the galactic plane) and the bulge population (mostly within 9$\degr$ of the galactic centre, and all within the 20$\degr$ circle in the plot). Nearly 41 per cent of all discovered novae are in this small clump. With this positional information alone, we see that any nova within something like 9$\degr$ of the galactic centre has a high probability of being a bulge nova. The gap at low galactic latitudes is prominent for the bulge novae, because they are roughly at 8000 pc distance and dimmed by very high extinction. The low-latitude zone-of-avoidance is not significantly visible outside of the bulge. Figure 2: Distribution over angle from galactic centre for 402 novae. One important point from this figure is to see the huge and narrow cluster of novae closely around the galactic centre, with these being the bulge population. This cluster is shown with an expanded angular scale in the inset figure. The best estimate for the number density of disc novae for the galactic centre region is shown by the red histogram. In the densest part of the bulge area, the probability that a nova is in the bulge varies from roughly 80–90 per cent, as based on the $\theta_{GC}$ alone. We see that few bulge novae appear with $\theta_{GC}$$>$13$\degr$, and no bulge novae appear more than 20$\degr$ from the galactic centre. A description of the bulge population distribution is that of a Gaussian with a sharp drop in the innermost region due to interstellar dust. While the small-number statistics and the dust absorption make for substantial uncertainties, the 68 per cent containment radius is roughly 5.4$\degr$. For a distance to the galactic centre of $D_{GC}$=8000 pc, this corresponds to a characteristic radius for the bulge population of $R_{bulge}$=750 pc.  Table 4: Bulge/Disc Population Identification for $\theta_{GC}$$<$20$\degr$ (full table with 214 novae is in on-line supplementary material) Nova |  $\theta_{GC}$ ($\degr$) |  $\mu_{old}$ (mag) |  $\mu_{peak}$ (mag) |  $\varpi$ (mas) | Population
---|---|---|---|---|---
V5854 Sgr | 1.00 | … |  $<$ 11.90 $\pm$ 3.13 | 1.43 $\pm$ 1.41 | bulge
V3730 Oph | 1.57 | … |  $<$ 12.60 $\pm$ 2.10 | -0.08 $\pm$ 0.70 | BULGE
V4092 Sgr | 1.77 | … |  $<$ 14.09 $\pm$ 1.69 | … | bulge
V2415 Sgr | 1.77 | … |  $<$ 16.09 $\pm$ 1.72 | … | bulge
V5586 Sgr | 1.79 | 12.74 $\pm$ 1.01 | 11.90 $\pm$ 1.69 | … | DISC
… |  |  |  |  |
V1313 Sco | 18.85 | 15.25 $\pm$ 0.76 | 13.71 $\pm$ 1.75 | … | BULGE
V841 Oph | 19.29 | … | 10.06 $\pm$ 1.49 | 1.19 $\pm$ 0.02 | DISC
V366 Sct | 19.53 | … |  $<$ 5.90 $\pm$ 9.87 | -0.32 $\pm$ 1.53 | DISC
V1662 Sco | 19.59 | 12.29 $\pm$ 1.01 |  $<$ 11.30 $\pm$ 4.86 | … | DISC
FV Sct | 19.68 | … |  $<$ 14.13 $\pm$ 1.92 | 0.48 $\pm$ 0.22 | disc

The distribution of galactic novae across the sky (see Fig. 1) shows two
distinct populations. The well-known novae (because they are bright from being
close our Sun) are in the disc population, which appear close to the galactic
plane all around the galactic equator. The bulge novae (those that cluster
within 20$\degr$ of the galactic centre) are clearly a distinct population.
This division of novae into disc and bulge populations is similar to the
division of all Milky Way stars into disc and bulge populations. Presumably
the bulge novae are just an ordinary part of our galaxy’s bulge, and represent
an older population. All of the bulge novae are relatively faint (none peaking
brighter than 7.3 mag), and so there are no famous bulge novae.

With the bulge novae being faint and obscure, little work has been done on
their distinct properties. Shafter (2008) provides a review of the results.
Estimated bulge fractions ranges from some small percentage (Duerbeck 1984) up
to around 75 per cent (Della Valle & Livio 1994). With a detailed model of
structures for the bulge stars, disc stars, and interstellar extinction,
Hatano et al. (1997), concluded “the true bulge fraction of Galactic classical
novae is much closer to 1/8 than to 1/2, i.e., most Galactic classical novae
are from the disc, not from the bulge". With these large uncertainties,
Shafter points out that external galaxies became the focal point for
population studies. Unfortunately, this produced contradictory studies on key
properties, for example, whether of not the $M_{V,peak}$ is bimodally
distributed or not, and on whether the specific rates (novae per year per unit
stellar mass) are correlated with the Hubble type of the galaxy. And we
recently have the conundrum that our Milky Way has 15-out-of-20 novae with
evolved companions in the bulge population (Schaefer 2022), while the
Andromeda Galaxy apparently has all of such nova in the disc population
(Williams et al. 2016). It is safe to say that little is known with useable
confidence about the galactic bulge nova demographics and properties. For
example, I know of no listing of galactic bulge novae, much less a compilation
of their properties.

The defining property of the bulge novae is their angular distance from the
galactic centre, $\theta_{GC}$. For this, I have calculated $\theta_{GC}$ for
all 402 nova, and constructed a histogram for the density of novae inside
annuli of 1$\degr$ widths, in units of number-per-square-degree (Fig. 2). This
histogram shows two distinct populations, the high clump with
$\theta_{GC}$$<$20$\degr$ for the bulge novae plus the low-flat component over
all $\theta_{GC}$ for the disc novae.

What is the disc component for $\theta_{GC}$$<$20$\degr$? It is possible to
try to use a detailed galactic model, but such would not have much confidence
due to not knowing how nova systems relate to the other stars in the general
model. For any model or empirical results, high accuracy will not be possible,
because we are dealing with small-number statistics, with there being 3 or
fewer disc novae in each annulus. There are also large systematic errors in
the nova detection rates around the galactic centre, as can be seen by the
large differences between negative and positive longitudes, as well as by the
asymmetries between the positive and negative latitudes near the centre. These
asymmetries are likely caused by a combination of the complex history of nova
search regions as well as in the galactic dust absorption. With these
asymmetries, there is no accurate means to interpolate the disc population
into the galactic centre region. A reasonable empirical method is to make
identical counts in annuli for cases where all the nova coordinates are
shifted by a constant in galactic longitude. So for example, if all the
longitudes are shifted by $+$40$\degr$, we have just 1 nova inside the
4.0$\degr$ to 5.0$\degr$ annulus, and if the longitudes are shifted by
$-$40$\degr$ then we have 2 novae. This is while the real sky, i.e., with zero
shift, has 20 novae in the same annulus, so we can divide these up into
approximately 18–19 bulge novae and 1–2 disc novae. This preserves the
statistics of the galactic latitude distribution as combined with the annuli
shape, and it ensures that we are only counting disc novae. To get useable
statistics, I have evaluated the number in each of the shifted annuli for
shifts of $\pm$50$\degr$, $\pm$40$\degr$, $\pm$30$\degr$, and $\pm$25$\degr$
for small annuli. There is no significant rise in numbers from 50$\degr$ to
25$\degr$. Averaging over these shifts and then smoothing over angles produces
my best estimate for the numbers and densities of disc novae inside the
galactic centre region. This is displayed as the red line in Fig. 2.

The bulge component rises high above the disc component for
$\theta_{GC}$$<$9$\degr$. For these novae, by the galactic coordinates alone,
the probability is high that any individual novae is in the bulge population.
The huge excess of bulge novae in Fig. 2 falls off sharply from 5$\degr$ to
13$\degr$. A case can be made that the observed number of novae outside
13$\degr$ is nearly consistent with the expected numbers from the disc
population. The excess in the observed novae over the expectations for disc
novae alone is just 15 novae from 13$\degr$$<$$\theta_{GC}$$<$20$\degr$, and
with the uncertainties, this is barely a ‘3-$\sigma$’ result. The density for
bulge novae outside of 20$\degr$ is certainly negligible.

What is the characteristic radius of the bulge population, $R_{bulge}$? I will
describe this characteristic radius using terminology for a Gaussian
distribution, with this usage as a reasonable description rather than a model
or theory claim. The measure of the 68 per cent containment radius has
substantial uncertainties due to the observed variation around any smooth
curve (see inset in Fig. 2), the uncertainties in the numbers of disc novae to
subtract out as ‘foreground’, and the sharp drop in numbers at the lowest
galactic latitudes. Nevertheless, I have fitted a Gaussian for the annuli from
2–20$\degr$. The Gaussian sigma is 5.4$\degr$. The formal error bar is
0.3$\degr$. But I expect that the real error bar is larger due to systematic
problems, most importantly due to the substantial changes in the nova
discovery efficiency across the galactic centre region, and the real
uncertainty is more like $\pm$1$\degr$.

The distance to the galactic centre, $D_{GC}$, has long been measured, and
with increasing accuracy. Reid (1993) reviewed all the prior measures and
concluded that $D_{GC}$=8000$\pm$500 pc. Malkin (2012) reviewed 52 measures of
the distance from 1992–2013, yielding a final combined best distance of
7980$\pm$15$\pm$20 pc. To all needed accuracy, I will adopt the round-number
of $D_{GC}$=8000 pc.

Now, we can turn the characteristic angular size of the bulge nova population
into its physical size. This is simply $R_{bulge}$=$D_{GC}$$\sin$(5.4$\degr$),
or 750 pc, with an uncertainty of roughly $\pm$130 pc. With this, along any
line of sight towards the galactic centre, every bulge nova must have a
distance of 8000$\pm$750 pc, with the uncertainty containing 68 per cent of
the population. This distance corresponds to a distance modulus of
14.5$\pm$0.2 mag and corresponds to a simple parallax of 0.125$\pm$0.012
milli-arcseconds (mas).

Now, with my compilation of all 402 known novae, I can pick out a complete
roster for the bulge population novae, with good confidence for each
individual novae. The first cut, based on the drop to no-excess above the disc
nova population, is that bulge novae are only with $\theta_{GC}$$<$20$\degr$.
Next, I require that each candidate bulge nova have a Gaia parallax (if
available) consistent with 0.125 mas. Most bulge novae are too faint to have a
Gaia parallax, so this requirement is mainly used to identify disc novae in
the galactic centre region as those with a parallax too large to be consistent
with the bulge distance. Further, I require that $\mu_{peak}$ be consistent
with 14.5 mag. Most bulge novae have poor measures of $\mu_{peak}$, so this
constraint is mainly useful for recognizing disc novae that are too bright to
be bulge novae. Plus, I require that any available old distance measures from
the literature be consistent with $D_{GC}$, which is to say that $\mu_{old}$
is consistent with 14.5 mag. For the 214 novae with $\theta_{GC}$$<$20$\degr$,
I have placed the values of $\mu_{old}$, $\mu_{peak}$, and the Gaia parallaxes
(see next Section) into Table 4. These can be used to find consistency or
inconsistency for each nova with a distance of $D_{GC}$.

Further constraints on the nova distances can be derived from their observed
extinctions and magnitudes: (1) If the observed extinction is greatly smaller
than possible for a $\sim$8000 pc distance, then the system must be a disc
nova. For the best example, consider V4643 Sgr, with its position close to the
galactic centre and $\it b$ of $-$0.34$\degr$. The total extinction along this
heavily-shrouded line-of-sight is 20.5 mag (Schlafly & Finkbeiner 2011), so if
V4643 Sgr were inside the bulge then its extinction would be $>$10 mag or so.
However, the observed extinction is 1.47$\pm$0.20 mag, and hence the nova must
be much closer than the bulge and must be part of the disc population. For a
different example, V366 Sct was observed to peak at 9.94 mag, but we have no
measure of its extinction. The line-of-sight has 8.4 mag of extinction
(Schlafly & Finkbeiner 2011), so a bulge nova must have $E(B-V)$$>$4 mag or
so, for $A_{V}$$>$12 mag. To be in the bulge, V336 Sct would need a peak
absolute magnitude more-luminous than $-$16 mag, which is certainly not a
nova. This method can demonstrate that 10 novae in the galactic centre region
are certainly of the disc population. (2) A further constraint comes from the
quiescent magnitudes with extinction corrections, $V_{q,0}$. This uses my
earlier result that novae in quiescence almost always have an absolute
magnitude more-luminous than $+$5 mag (Schaefer 2018; see also Patterson et
al. 2022). So any nova appearing with $V_{q,0}$$>$19.5 is unlikely to be in
the disc population. For the specific example of V4444 Sgr, the extinction is
0.56 mag or less (Schlafly & Finkbeiner 2011), the quiescent magnitude is
$>$21 (CVCat), so the distance modulus must be $>$14.3, which demonstrates a
bulge population. Twelve novae in the galactic centre region are thus shown to
be bulge novae. (3) A similar constraint comes because few classical novae
have quiescent absolute magnitudes more-luminous than $+$3 mag. The only
exceptions are RN and those systems with subgiant and giant companions, with
these being recognized by their infrared colors, even at bulge distances
(Schaefer 2022). Hence, a normal bulge nova (with a distance modulus near 14.5
mag) will appear fainter than 16.5 mag. This can be turned around to say that
a nova with $V_{q,0}$$<$16.5 is likely a disc nova. For example, V732 Sgr is
seen at $V_{q}$=16.9 (Mroz et al. 2015) with extinction of 0.81$\pm$0.16 mag,
so $V_{q,0}$=14.4 at the distance of the bulge the absolute magnitude would
have to be more-luminous than $-$0.1 mag, which is to imply that the system is
in the disc population. With this method, five novae in the galactic centre
region can be assigned to the disc population.

For many novae, the evidence is clear as to whether the nova is bulge or disc.
These are indicated in the last column of Table 4 with either “DISC" or
“BULGE". Out of the 214 novae in Table 4, 124 have a confident population
assignment. Most disc novae will have a clear signature. That is, they are
usually bright enough to have one of the ‘old’ methods applied, or to have
their $\mu_{peak}$$\ll$14.5, or to be near enough that Gaia can detect a large
parallax. I find 14 disc novae for 0$\degr$$<$$\theta_{GC}$$<$6$\degr$, 17
disc novae from 6$\degr$ to 12$\degr$, and 4 disc novae in the range
12–18$\degr$, with this being consistent with my prior estimates.

Nevertheless, many novae in Table 4 do not have a confident population. A good
case can be made that the remaining novae are almost all in the bulge
population. First, such novae will be those that are relatively faint and
relatively far, which is to say that most of the cases will be bulge novae.
Second, roughly all of the disc novae in the bulge cluster of Fig. 2 are now
identified, and the remaining novae can only be bulge sources so as to account
for the huge excess at low $\theta_{GC}$. For example, in the 0–6$\degr$ zone,
9 disc novae are expected, 14 disc novae are now confidently identified, and
the zone has 83 novae, so nearly all of the 83-14=69 remaining novae must be
bulge systems. Similarly, for the 6–12$\degr$ zone, 17 disc novae are
expected, 17 disc novae have been identified, so the remaining 75 novae must
be almost entirely bulge novae. In the 12–18$\degr$ zone, the 24 remaining
novae (i.e., those not already identified as being disc population) must have
14 or more that are bulge systems.

I can present a good case for the probability being high for many of the novae
being bulge systems, even without any good Gaia parallax or other data. In the
0–12$\degr$ zone, the probability of such stars being a bulge system is
$\gtrsim$95 per cent, simply as required to make the bulge contribution in
Fig. 2 while all the disc novae are already identified. Further, these systems
have faint $V_{peak}$ and have either no Gaia counterpart or have the Gaia
counterpart with a near-zero parallax, so the lack of good data are confident
signs that these systems are not disc novae. That is, any disc nova seen in
the foreground of the bulge will be brighter than a bulge novae, which makes
for a substantially great likelihood that Gaia will detect the counterpart and
return a parallax that is significantly larger than 0.125 mas, and which makes
for a substantially greater likelihood that the disc nova will have a distance
measure from one of the old methods. While any high accuracy is impossible, I
estimate a probability of 10 per cent or lower that a nova with no Gaia
counterpart (and no distance measures from any of the old methods) is at a
distance significantly closer than 8000 pc. The combination of these two
probabilities gives $\gtrsim$99.5 per cent that each individual remaining
novae is a bulge system.

This probability estimate of $\gtrsim$99.5 per cent has substantial
uncertainties in its application. First, just because the expected number of
disc nova interlopers is already overfilled does not mean that some small
number of additional interlopers cannot be hiding amongst the poorly observed
events. Second, a disc nova with a distance around 6000 pc could easily
produce a Gaia counterpart whose parallax is too poor to be recognize as not
being a bulge source, and such a nova could easily be too faint to trigger any
of the various old methods to recognize its distance. Third, in the outer
zones, I have not recognized the expected number of disc novae, so likely a
few more unidentified disc interlopers are hiding around the edges of the
bulge. Nevertheless, the basic probability result (that almost all of the
novae in Table 4 not identified as “DISC" must be in the bulge population) is
still confident, because the bulge-identifications are required to get the
high numbers in the bulge component of Fig. 2. Therefore, the remaining non-
DISC novae in Table 4 are almost all in the bulge population and are
designated by ‘bulge’, with lower case letters.

Some novae do not neatly fit into the ‘bulge’ classification. These cases have
population assignments of ‘disc’, ‘disc?’, and ‘bulge?’. Here are three
examples to illustrate each of these population assignments: (1) KY Sgr has a
parallax of $-$0.02$\pm$0.10 mas, clearly indicating a distance comparable to
$D_{GC}$. This nova has extinction of 0.55 mag (Shafter 1997) presumably from
colors in quiescence, and 1.0$\pm$0.5 mag from my fits to the spectral energy
distribution (Schaefer 2022). The extinction along the entire line-of-sight is
3.29 mag (Schlafly & Finkbeiner 2011), while most of this must come from
distances closer than the bulge (because with galactic latitude -1.72$\degr$
the line-of-sight past the bulge is already far outside the disc). The
discrepancy arises in trying to understand how KY Sgr can suffer much less
than the maximum extinction, unless its distance is significantly closer than
the 8000 pc. I do not know how to resolve this discrepancy, so I am labeling
this system as ‘bulge?’. (2) Some of the novae have apparently contradictory
information. For example, V630 Sgr has a parallax of 0.14$\pm$0.11 mas
pointing to a bulge distance (with parallax near 0.125 mas), yet has a well-
observed peak with $V_{peak,0}$=2.2 (implying a peak absolute magnitude of
$-$12.3 for a galactic centre distance). In this case, I reconcile the two
measures to a distance of 4000 pc, corresponding to a one-sigma deviation from
the best-estimate parallax and corresponding to a peak absolute magnitude of
$-$10.8 mag at the extreme end of the known distribution. I am labeling this
as a ‘disc?’ nova. (3) The ‘disc’ novae are those with the measures pointing
to the disc population, yet for which the evidence does not produce high
confidence. FV Sct has a parallax of 0.48$\pm$0.22 mas, for which the simple
calculation gives a distance of 2000 pc, indicating a disc population.
However, a parallax of 0.125 mas for bulge sources is only 1.6-sigma off the
best-estimate parallax, so the parallax alone does not yield a decisive
answer. The only other useful measure, $\mu_{peak}$$<$14.13$\pm$1.92, is
ambiguous, where the large error bars allow for both usual disc and bulge
distances. I am labeling this case as ‘disc’ for the most likely population,
but the lower case lettering indicates that this result is not of high
confidence.

A minor question concerns the two novae that are inside globular clusters.
Globular clusters are certainly in the older bulge (or halo) population, but
the dynamical histories of these two novae are likely greatly different from
the other bulge novae. I will dodge this question by assigning these to a
separate “GlobC" population type.

In the end, many population assignments have good confidence as based on
measured distances (the 38 ‘DISC’ and 86 ‘BULGE’ novae), most of the remainder
have assignments with good confidence due to the requirement to get the large
numbers of bulge novae as an excess above the disc component (the 75 ‘bulge’
novae), while a small fraction have assignments that are likely correct but
individually of lesser confidence (the 4 ‘bulge?’, 9 ‘disc?’, and 2 ‘disc’
novae). Of the 214 novae in Table 4, 165 are identified as being in the bulge.
The bulge fraction for all 402 known galactic novae is 41 per cent. This is
the first list of bulge novae that I am aware of. And now, this list can be
used for appropriate priors in the distance calculation.

##  5 GAIA DR3 PARALLAXES

Table 5: Gaia Parallaxes and Magnitudes for 215 Galactic Novae (full table with 215 novae is in on-line supplementary material) Nova |  $\varpi$ (mas) |  $b$ (mag) |  $g$ (mag) |  $r$ (mag)
---|---|---|---|---
OS And | 0.21 $\pm$ 0.11 | 18.29 | 18.14 | 17.82
CI Aql | 0.38 $\pm$ 0.04 | 16.43 | 15.79 | 14.94
DO Aql | 0.35 $\pm$ 0.18 | 18.10 | 18.15 | 17.04
EL Aql | 0.16 $\pm$ 0.08 | 18.10 | 16.59 | 15.42
EY Aql | -0.67 $\pm$ 0.70 | 21.05 | 20.20 | 19.12
… |  |  |  |
NQ Vul | 0.84 $\pm$ 0.07 | 18.02 | 17.29 | 16.43
PW Vul | 0.47 $\pm$ 0.08 | 17.85 | 17.66 | 17.21
QU Vul | 1.11 $\pm$ 0.31 | 19.70 | 19.56 | 18.80
QV Vul | 0.38 $\pm$ 0.18 | 18.87 | 18.56 | 17.86
V458 Vul | 0.19 $\pm$ 0.11 | 18.30 | 18.10 | 17.80

On 2022 July 13, the Gaia Team released the much-anticipated Data Release 3
(DR3), with its impressive collection of parallaxes for stars down to roughly
19th magnitude and fainter from all over the sky. For the nova community, we
finally have a collection of accurate and reliable distances for a large
number of novae.

Gaia DR3 is part of a progression with great improvements in accuracy and
number. Take the case of the brightest old novae, V603 Aql. Reported
parallaxes are $\varpi$=4.011$\pm$0.137 from $HST$ (Harrison et al. 2013),
2.92$\pm$0.54 mas from Gaia DR1 (Ramsay et al. 2017), 3.191$\pm$0.069 mas from
Gaia DR2 (Schaefer 2018), 3.11$\pm$0.03 mas from Gaia EDR3, and now
3.106$\pm$0.034 mas from Gaia DR3. The number of novae with accurate
parallaxes progressed from 4 for $HST$, to 3 for DR1, 41 for DR2, and now 74
for DR3.

The Gaia spacecraft is described in Gaia Collaboration et al. (2016), while
DR3 is described in Gaia Collaboration et al. (2022). DR3 data can be accessed
from a European Space Agency website444https://gea.esac.esa.int/archive/.

A bureaucratic mode for extracting the Gaia parallaxes would be to run the
standard search program and record the parallax for the star nearest to the
nova position. But this mindless approach would be bad for the majority of
novae. One reason is that many dozens of novae have no identified quiescent
counterpart, and no accurate position, so that the parallax for the Gaia star
nearest to the cataloged nova position has likely no connection to the nova
parallax. Another reason is that $\sim$10 per cent of the faint novae have
well-known counterparts that are more than one arc-second away from the
catalogued positions, so a blind search would likely turn up the wrong answer.
Further, many novae have a crowded field, such that many stars are close to
the known nova position, so it is unclear as to which Gaia star is the real
counterpart. A final problem is that many novae have the counterpart being
faint, below the Gaia threshold, while the blind positional-coincidence method
will then often take the meaningless parallax for a foreground star.

A proper use of the Gaia database for nova requires that some sort of a
positive connection be made between the nova counterpart and the Gaia star.
This connection can be made when the counterpart is known to be isolated to
substantially fainter than the known counterpart magnitude, and the Gaia star
is similarly isolated and of roughly the same magnitude as the counterpart.
Further evidence might be that the Gaia star is relatively blue in color, or
perhaps noted as a variable star. For the not-simple cases, I have used the
Gaia catalog to construct a small star chart showing the relative positions
and magnitudes, for direct comparison with a deep image on which the
counterpart is positively identified. Excellent finder charts appear in the
SMARTS catalog (Walter et al. 2012), the Duerbeck catalog (Duerbeck 1987), and
the CVCat (Downes & Shara 2001). For purposes of this paper, I have included
the Gaia parallax only when I can convince myself that the evidence is good
for the Gaia star being the nova counterpart.

I have exhaustively searched for a confident Gaia counterpart for each of the
402 known galactic novae. In the majority of the cases, this has entailed
making a star chart of the Gaia stars for comparison with picture of the real
sky with tick marks identifying the counterpart or its location. For many
other novae, the search consisted of seeing that Gaia recorded no stars within
2 arc-seconds of the nova position, and confirming in some other source that
the Gaia position is the correct one. In 20 cases, Gaia DR3 reports on the
nova counterpart, but no parallax is included. I have found a total of 195
nova parallaxes with DR3. From this, only 74 galactic novae have ‘good’
accuracy. Here ‘good’ accuracy is taken to be where the uncertainty on the
parallax is $<$0.30 times the parallax ($\sigma_{\varpi}$ $<$0.30$\varpi$),
with this being the limit beyond which the prior contributes more to the final
distance than does the new parallax information. For parallaxes with
uncertainties from 0.30 to 1.0 times the parallax, I will label these measures
as “poor”, for which my list has 66 novae. When $\sigma_{\varpi}$$>$$\varpi$,
there is still marginal information, effectively just defining a lower limit
on the nova distance, for which I have 55 novae from the DR3 catalog. Out of
these near-zero parallaxes, 36 are actually negative parallaxes.

All of the 215 Gaia counterparts have their parallaxes and magnitudes reported
in Table 5. The first column gives the nova name in the correct GCVS order,
the second column gives the Gaia DR3 parallax in mas, and the last three
columns give the Gaia magnitudes in the $b$, $g$, and $r$ bands. To get
distances in parsecs, these parallaxes must be combined with the priors from
$\mu_{old}$ (see Table 1), $\mu_{peak}$ (see Table 3), and the population
assignment (see Table 4).

##  6 USING ALL THE INFORMATION TO GET THE BEST DISTANCES

The simple and traditional calculation of distance ($D$ in parsecs) from a
parallax ($\varpi$ in mas with uncertainty $\sigma_{\varpi}$) is that
$D=1000/\varpi$ with an uncertainty of
$\sigma_{D}=D*(\sigma_{\varpi}/\varpi$). This is fine when the fractional
error of the parallax is small. When the fraction error ($\it
f$=$\sigma_{\varpi}/\varpi$) is not small, substantial problems arise (Bailer-
Jones 2015). For $\it f$$\gtrsim$0.30, the calculated probability distribution
can become bimodal (where the results are telling us more about the prior
information than about any new input), so the 30 per cent threshold is fine
for recognizing parallaxes with good accuracy. To account for the non-
linearities, the solution is to use a Bayesian calculation, as recommended by
the Gaia Team (Luri et al. 2018). Detailed and helpful explanations and
examples are given in Bailer-Jones (2015).

The $\it unnormalized$ probability for the nova being at distance $D$, given
the measured $\varpi$ and $\sigma_{\varpi}$, is

$P(D|\varpi,\sigma_{\varpi})=P(\varpi|D,\sigma_{\varpi})~{}P(D).$ (3)

The first factor on the right side of the equality is the probability that a
nova at distance D will return a measured parallax of $\varpi$. The second
factor on the right side is the ‘prior’, which encapsulates all previous
knowledge of the nova distance. The first factor is

$P(\varpi|D,\sigma_{\varpi})=\frac{1}{\sigma_{\varpi}}exp\left[\frac{-1}{2\sigma_{\varpi}^{2}}(\varpi-\frac{1}{D})^{2}\right].$
(4)

Throughout, the probability distributions can be multiplied by a normalization
factor (i.e., the function integrated over all $D$) so that the integral of
all the final probabilities is unity.

The prior information included in $P(D)$ can come from a variety of sources.
Here, I will be including the information of the galactic position, the
distance modulus from the old methods, and the distance modulus from
$V_{peak}$. These are multiplicative, so

$P(D)=P_{gal}(D|\ell,{\it b})\times P_{old}(D|\mu_{old})\times
P_{peak}(D|\mu_{peak}).$ (5)

The inclusion of these factors depends on the prior information for the nova,
before and independent of the Gaia parallax.

The $P_{gal}$ factor is representing the number of novae along a sightline as
a function of distance, and this is the product of the nova space density as a
function of distance times the volume of space in the expanding cone of the
sightline. The $P_{gal}$ factor depends on whether the nova is in the bulge or
disc population. For a disc population,

$P_{gal}(D)=D^{2}\times\exp\left[\frac{-D\sin({|\it
b}|)}{\langle|Z|\rangle}\right]\times\exp\left[\frac{-R_{GC}}{h_{R}}\right].$
(6)

The $D^{2}$ factor represents the greater volume of space as we go to larger
and larger distances. The first exponential factor represents the fact that
disc populations have their number density decreasing exponentially with their
vertical distance from the centre of the galactic plane, $Z$=$D$$\sin({\it
b})$. Disc novae are observed to have an average value of $|Z|$, i.e., the
exponential scale height $\langle|Z|\rangle$, for which I measure 140 pc (see
Section 7.1). Along the line of sight towards a galactic latitude of $\it b$,
the space number density of disc novae will fall off exponentially with
distance. The exponential term involving the galactocentric distance,
$R_{GC}$, is to represent the known exponential fall-off in star density of
our Milky Way, with the scale length, $h_{R}$, roughly equal to 3000 pc. The
value of $R_{GC}$ is just a function of $D$, $D_{GC}$, and the galactic
longitude $\ell$. This representation of our galaxy does not incorporate any
spiral arms or a bar in the centre. The exponential in $R_{GC}$ has little
effect on any distances, other than to cap the distances for poorly-observed
disc novae at low galactic latitude. This formulation has suppressed constant
factors, as these all are absorbed into a normalization factor. This is the
‘exponentially decreasing space density’ (EDSD) prior (see equation 18 of
Bailer-Jones 2015) recommended by the Gaia Team (Luri et al. 2018).

For a bulge novae, we can represent their radial distribution as a Gaussian
along any line of sight with a central distance of $D_{GC}$ and a one-sigma
scatter of $R_{bulge}$. As a useable approximation for bulge novae, our prior
information includes a Gaussian in $D$;

$P_{gal}(D)=D^{2}\times\exp\left[-\frac{1}{2}\frac{(D-D_{GC})^{2}}{R_{bulge}^{2}}\right].$
(7)

Again, the $D^{2}$ factor covers the expanding volume at greater distances. I
adopt $D_{GC}$=8000 pc and $R_{bulge}$=750 pc. All of the galactic novae will
have the $P_{gal}$ prior from either equation 6 or 7.

The prior information from the old methods and from $V_{peak}$ have the
distance moduli distributed as a Gaussian. For the prior based on the old
methods,

$P_{old}(D|\mu_{old})=\exp\left[-\frac{1}{2}\frac{(5Log[D]-5-\mu_{old})^{2}}{\sigma_{old}^{2}}\right].$
(8)

Many of the old measures from extinction are lower limits, and this can be
handled by making the $\sigma_{old}$ to be very large for any distance larger
than the limit. In the closer direction, the quoted $\sigma_{old}$ should be
used as a reflection of the uncertainty in the value of the limit. Similarly,
the prior for the distance information from $V_{peak}$ will be

$P_{peak}(D|\mu_{peak})=\exp\left[-\frac{1}{2}\frac{(5Log[D]-5-\mu_{peak})^{2}}{\sigma_{peak}^{2}}\right].$
(9)

Many novae only have faint limits on $V_{peak}$, or upper limits on
$\mu_{peak}$. This should be handled by setting $\sigma_{peak}$ to the
tabulated value for distances larger than the tabulated limit (to represent
the uncertainty in the limit) or to a very large number for distances less
than the tabulated limit (to represent the limit on the distance). With this,
we can calculate the overall probability distribution for each nova, as a
function of D and observed parameters.

This Bayesian formulation has a strong advantage that it provides a natural
means to collect together all available information on $D$, where the old
methods and the $V_{peak}$ are correctly combined with the new Gaia
parallaxes. The results are the best possible distances, taking into account
all inputs. This is what I am presenting as the “Overall Best Distances" in
this paper’s title.

The calculated probability as a function of distance (from equation 3) should
be normalized to an area under the curve of unity. (For display purposes, the
probability curves are best normalized so that the peak probability is at
unity, as then the shapes are not misperceived due to radical changes in the
heights.) The resultant distribution functions always have an asymmetric and
non-standard shape. (That is, the distributions are not Gaussians in
distance.) These distributions record all the best information on $D$.
However, presenting these distributions is awkward, and comparisons are hard.
The solution is to extract from each distribution the most probable $D$ and
some range for representing the uncertainties. Following the recommendation of
Bailer-Jones, I am using the mode of the probability distribution as the best
estimator of $D$. That is, the $D$ values I list will be for those at the
maximum probability of the probability distribution. Further, to represent the
reasonable range of $D$, I will not use the $\pm$ notation (e.g.,
1210${}^{+390}_{-220}$ pc), but will instead quote a range of $D$ (e.g.,
990–1600 pc). The range I chose to describe is that which contains the central
68 per cent of the probability distribution. The reason for choosing 68 per
cent is because astronomers are practiced at knowing the meaning, whereas
other choices would only be confusing.

Figure 3: The probability distributions for V723 Cas. The final probability
distribution is the unnormalized product of four separate probability
distributions, each representing information on the distance to the nova. The
$P_{gal}$ distribution (solid green curve) represents the knowledge about the
real distribution of novae in our galaxy, in this case for the space density
of disc novae falling off exponentially with distance from the centre plane of
our galaxy. The $P_{old}$ distribution (solid red curve) represents the old
measure of the expansion parallax as 3860 pc, with a real uncertainty of near
1690 pc. The $P_{peak}$ distribution (dashed blue curve) is based on the
observed peak magnitude of 7.10$\pm$0.10, the observed $E(B-V)$=0.40$\pm$0.10,
and the adopted average for all novae of $M_{V,peak}$ of $-$7.0 mag. The broad
width of this distribution is because the one-sigma on the peak absolute
magnitude being $\pm$1.4 mag. The $P(\varpi|D,\sigma_{\varpi})$ distribution
(orange dashed curve) is from the Gaia DR3 parallax of 0.183$\pm$0.035 mas.
The $P(D|\varpi,\sigma_{\varpi})$ distribution (solid black curve) is the
final best estimate of the probability of V723 Cas being at the given
distance. This final curve is simply the product of the four input curves as
displayed. (For display purposes only, the distributions have all been
normalized so that the maximum probability is unity.) The narrowest of the
four distributions is from the Gaia parallax, so the other three distributions
serve only to push the distance somewhat closer. In the end, the best estimate
of the distance to V723 Cas is that the highest point in the final curve is at
4880 pc, while the central 68 per cent of probability is inside the range
4390–5910 pc.

To illustrate this calculation (see Fig. 3), let me take the case of V723 Cas,
as a typical nova with a moderate fraction error in the parallax ($\it
f$=0.19), plus an old measure of the expansion parallax and a well measured
peak magnitude. In Cassiopeia, the nova is certainly in the disc population
and with a galactic latitude of $\it b$ at -8.81$\degr$. Just given this
galactic position, distances closer than 600 pc or so are unlikely simply
because there is little volume inside this distance, while distances farther
than 6000 pc or so are unlikely due to the nova then being required to be very
far below the galactic centre plane. So just from the galactic position alone,
the expected distance can be narrowed down to a range that is a factor of
10$\times$ in size. For the old measures, we have an expansion parallax with a
distance of 3860 pc, but the real uncertainty is much larger than published,
as represented by the broad red curve in Fig. 3. For the $P_{peak}$
information, the best estimate distance is 3730 pc as based on the peak
magnitude alone. However, the $\pm$1.4 mag uncertainty on our adopted absolute
means that the $P_{peak}$ distributions will always be very broad. The Gaia
parallax provides the best information, but even this is only accurate at the
19 per cent level. When all four of these distributions are multiplied
together, the three non-parallax factors only serve to push the final product
to the near-side of the distribution allowed by the parallax. The parallax
alone is pointing to distances centred on 5450 pc, but all three of the other
sources of information are pointing to nearer distances, and these provide a
weak pull on the parallax to produce a final distance of 4880 pc as the most
probable value.

Table 6: Distances and Properties of All 402 Known Galactic Novae (Supplementary Material has additional columns for $\ell$, b, $\Theta_{GC}$, $E(B-V)$, $t_{2}$, and $\varpi$) Nova | Year | LC($t_{3}$) | $V_{peak}$ | Spec. | FWHM | $P$ | Pop. |  $D$ (68% range) | $M_{V}$ | Propertiesa
---|---|---|---|---|---|---|---|---|---|---
OS And | 1986.9 | D(23) | 6.50 $\pm$ 0.10 | … | 1740 | … | DISC | 4152 ( 3549 – 5349 ) | -7.06 | …
CI Aql | RN | P(32) | 9.00 $\pm$ 0.10 | … | 2250 | 0.61836 | DISC | 2761 ( 2555 – 3143 ) | -5.84 | SubG, Ecl, $\Delta P$, $\dot{P}$
DO Aql | 1925.7 | F(900) | 8.50 $\pm$ 0.10 | Fe II | … | 0.16776 | DISC | 3151 ( 2571 – 4826 ) | -4.89 | Ecl
EL Aql | 1927.6 | J(25) | 5.32 $\pm$ 0.18 | … | 1230 | … | DISC | 4419 ( 3781 – 6450 ) | -10.91 | …
EY Aql | 1926.7 | S(40) | 9.69 $\pm$ 0.54 | … | … | … | DISC | 5819 ( 4214 – 9613 ) | … | …
V356 Aql | 1936.7 | J(140) | 7.00 $\pm$ 0.10 | Fe II | 1140 | 0.42651 | DISC | 3243 ( 2668 – 5725 ) | … | …
V368 Aql | 1936.8 | S(42) | 5.30 $\pm$ 0.20 | Fe II | … | 0.69051 | DISC | 2532 ( 2324 – 2948 ) | -8.58 | SubG, Ecl
V500 Aql | 1943.7 | S(43) | 6.13 $\pm$ 0.30 | He/N | 1400 | 0.14526 | DISC | 3291 ( 2655 – 4736 ) | -6.95 | …
V528 Aql | 1945.7 | S(38) | 6.90 $\pm$ 0.10 | Fe II, Ne | 915 | … | DISC | 2971 ( 2297 – 5479 ) | … | …
V603 Aql | 1918.4 | O(12) | -0.50 $\pm$ 0.10 | Hybrid | … | 0.13820 | DISC | 324 ( 320 – 327 ) | -8.30 | Shell
V604 Aql | 1905.7 | S(25) | 7.59 $\pm$ 0.25 | … | 1050 | … | DISC | 4631 ( 3508 – 7268 ) | -7.91 | …
V606 Aql | 1899.3 | P |  $<$6.4 $\pm$ 0.25 | … | 1280 | … | DISC | 3417 ( 2235 – 5688 ) | … | DN
V841 Aql | 1951.5 | … |  $<$9.9 $\pm$ 1.02 | … | … | … | DISC | 8178 ( 6238 – 13144 ) | … | DN
V1229 Aql | 1970.3 | P(32) | 6.60 $\pm$ 0.10 | Fe II | … | … | DISC | 3317 ( 2734 – 4732 ) | -7.55 | Shell
V1301 Aql | 1975.4 | S(85) | 10.30 $\pm$ 0.30 | He/N | 1800 | … | DISC | 3537 ( 2852 – 5418 ) | … | …
V1370 Aql | 1982.1 | D(29) | 7.70 $\pm$ 0.10 | Ne | 730 | 1.9581 | DISC | 3047 ( 2538 – 5209 ) | -5.80 | SubG
V1378 Aql | 1984.9 | … |  $<$10.0 $\pm$ 0.20 | … | … | … | DISC | 3136 ( 2715 – 6142 ) | … | …
V1419 Aql | 1993.4 | D(32) | 7.60 $\pm$ 0.10 | … | … | … | DISC | 4553 ( 3673 – 6276 ) | -7.24 | …
V1425 Aql | 1995.1 | S(79) | 8.00 $\pm$ 0.10 | Fe II | 1340 | 0.2558 | DISC | 3905 ( 2807 – 6884 ) | … | IP?
V1493 Aql | 1999.5 | C(50) | 10.10 $\pm$ 0.10 | … | 3340 | 0.156 | DISC | 3948 ( 3120 – 5996 ) | -4.65 | …
V1494 Aql | 1999.9 | O(16) | 4.10 $\pm$ 0.10 | Fe II, Ne | 2470 | 0.13462 | DISC | 858 ( 784 – 1011 ) | -7.43 | Ecl
V1548 Aql | 2001.4 | J | 10.80 $\pm$ 0.30 | Fe II | 1100 | … | DISC | 7292 ( 5421 – 11337 ) | … | …
V1721 Aql | 2008.7 | … |  $<$14.0 $\pm$ 0.20 | He/N | 6450 | … | DISC | 7683 ( 5973 – 11366 ) | … | …
V1722 Aql | 2010.0 | S(16) | 10.29 $\pm$ 0.10 | Fe II | 1000 | … | DISC | 7384 ( 5886 – 10477 ) | -8.70 | …
V1723 Aql | 2010.8 | … |  $<$12.4 $\pm$ 0.20 | Fe II | 1500 | … | DISC | 8354 ( 5996 – 13512 ) | … | …
V1724 Aql | 2012.9 | … | 12.00 $\pm$ 0.50 | Fe II | 950 | … | DISC | 6233 ( 4168 – 10328 ) | … | …
V1830 Aql | 2013.9 | … | 15.20 $\pm$ 0.20 | Fe II | 1260 | … | DISC | 9166 ( 7411 – 13313 ) | … | …
V1831 Aql | 2015.8 | D |  $<$14.7 $\pm$ 0.20 | Fe II | 1350 | … | DISC | 7486 ( 5258 – 12917 ) | … | …
V2000 Aql | 2020.5 | … |  $<$15.6 $\pm$ 0.20 | Fe II | 2000 | … | DISC | 7480 ( 5046 – 11414 ) | … | …
V2029 Aql | 2020.6 | … |  $<$13.35 $\pm$ 0.20 | Fe II | … | … | DISC | 6795 ( 4446 – 10871 ) | … | …
V2030 Aql | 2021.4 | … |  $<$17.5 $\pm$ 0.20 | He/N | 2200 | … | DISC | 8979 ( 6410 – 15454 ) | … | …
OY Ara | 1910.3 | S(80) | 5.77 $\pm$ 0.21 | … | … | 0.15539 | DISC | 2731 ( 2359 – 3795 ) | -7.40 | Ecl
T Aur | 1892.0 | D(84) | 4.50 $\pm$ 0.10 | Fe II | … | 0.20438 | DISC | 838 ( 815 – 870 ) | -6.42 | Ecl, Shell
QZ Aur | 1964.8 | … |  $<$5.4 $\pm$ 0.23 | … | … | 0.35750 | DISC | 2478 ( 2212 – 3296 ) | … | Ecl, $\Delta P$, $\dot{P}$
Z Cam | <c. 700 | … | … | … | … | 0.28984 | DISC | 214 ( 213 – 216 ) | … | DN
AT Cnc | c. 1686 | … |  $<$3 $\pm$ 0.20 | … | … | 0.20163 | DISC | 465 ( 459 – 473 ) | … | DN
V435 CMa | 2018.3 | D(63) | 9.90 $\pm$ 0.10 | Fe II | 1250 | … | DISC | 4079 ( 3069 – 6689 ) | -5.54 | …
RS Car | 1895.3 | J(80) | 7.10 $\pm$ 0.32 | … | … | 0.08244 | DISC | 5365 ( 3936 – 9265 ) | … | InGap, NonOrbP
V365 Car | 1948.5 | S(530) | 9.29 $\pm$ 0.51 | … | … | 0.22369 | DISC | 2884 ( 2560 – 4362 ) | … | …
V679 Car | 2008.9 | S(24) | 7.80 $\pm$ 0.10 | Fe II | 2000 | … | DISC | 6975 ( 5725 – 9652 ) | -8.28 | …
V834 Car | 2012.2 | S(38) | 10.20 $\pm$ 0.20 | Fe II | 1690 | … | DISC | 8897 ( 7363 – 11641 ) | -6.13 | …
V906 Car | 2018.3 | J(64) | 5.90 $\pm$ 0.20 | Hybrid | 325 | … | DISC | 3724 ( 2887 – 7554 ) | … | …
V919 Car | 2014.4 | … |  $<$10.1 $\pm$ 0.20 | … | … | … | DISC | 5338 ( 4106 – 8947 ) | … | …
V946 Car | 2012.7 | … |  $<$9.7 $\pm$ 0.20 | … | … | … | DISC | 3330 ( 2704 – 6650 ) | … | …
BC Cas | 1929.6 | … |  $<$9.7 $\pm$ 0.63 | … | … | … | DISC | 1896 ( 1742 – 2200 ) | … | …
V705 Cas | 1993.9 | D(67) | 5.70 $\pm$ 0.10 | Fe II | … | 0.22828 | DISC | 2175 ( 2004 – 2491 ) | -7.26 | Shell
V723 Cas | 1995.6 | J(299) | 7.10 $\pm$ 0.10 | Fe II, Ne | 600 | 0.69327 | DISC | 4622 ( 4183 – 5482 ) | -7.46 | SubG, V1500, Sh
V1391 Cas | 2020.7 | D(120) | 10.60 $\pm$ 0.10 | Fe II | … | … | DISC | 3784 ( 2789 – 6750 ) | … | …
V1405 Cas | 2021.3 | J(175) | 5.20 $\pm$ 0.10 | Hybrid | … | 0.18839 | DISC | 1809 ( 1630 – 1848 ) | -7.79 | $\gamma$
MT Cen | 1931.4 | D(10) | 7.74 $\pm$ 0.23 | … | 910 | … | DISC | 5260 ( 3892 – 9442 ) | … | …
V812 Cen | 1973.3 | … |  $<$10.4 $\pm$ 0.23 | Fe II | 1800 | … | DISC | 4118 ( 3022 – 7230 ) | … | …
V842 Cen | 1986.9 | D(48) | 4.90 $\pm$ 0.10 | Fe II | 760 | … | DISC | 1372 ( 1300 – 1472 ) | -7.65 | Shell, IP?
V868 Cen | 1991.3 | J(82) | 8.70 $\pm$ 0.10 | Fe II | 700 | … | DISC | 3890 ( 3034 – 6122 ) | -9.67 | …
V888 Cen | 1995.1 | O(90) | 8.00 $\pm$ 0.10 | Fe II | … | … | DISC | 2937 ( 2681 – 3459 ) | -5.39 | …
V1039 Cen | 2001.7 | J(174) | 9.30 $\pm$ 0.10 | … | … | 0.247 | DISC | 3483 ( 2776 – 6748 ) | … | IP?
V1047 Cen | 2005.6 | P(26) | 8.50 $\pm$ 0.20 | Fe II | 840 | … | DISC | 4174 ( 3295 – 6463 ) | -7.70 | Rebrighten(2019)
V1065 Cen | 2007.1 | P(26) | 6.60 $\pm$ 0.20 | Fe II, Ne | 2700 | … | DISC | 3322 ( 2687 – 4980 ) | -7.46 | …
V1213 Cen | 2009.3 | S(30) | 8.50 $\pm$ 0.10 | Fe II | 2300 | 0.21201 | DISC | 5437 ( 4575 – 7587 ) | -7.97 | DN
V1368 Cen | 2012.3 | P(34) | 9.40 $\pm$ 0.10 | Fe II | 1140 | … | DISC | 6345 ( 5168 – 8539 ) | … | …
V1369 Cen | 2014.0 | D(65) | 3.30 $\pm$ 0.10 | Fe II | 408 | 0.15656 | DISC | 643 ( 531 – 1048 ) | -6.08 | $\gamma$
V1375 Cen | 2010.6 | … |  $<$10.3 $\pm$ 0.20 | … | 1400 | 0.3604 | DISC | 1042 ( 1005 – 1087 ) | … | …
V1404 Cen | 2015.2 | S |  $<$10.7 $\pm$ 0.20 | … | … | … | DISC | 7800 ( 6088 – 12341 ) | … | …
V1405 Cen | 2017.4 | J(115) | 10.90 $\pm$ 0.30 | Fe II | 1600 | … | DISC | 7058 ( 5311 – 11759 ) | … | …
Table 7: continued

Distances and Properties of All 402 Known Galactic Novae  Nova Year
LC($t_{3}$) $V_{peak}$ Spec. FWHM $P$ Pop. $D$ (68% range) $M_{V}$ Propertiesa
IV Cep 1971.5 S(37) 7.00 $\pm$ 0.40 Fe II … … DISC 6463 ( 5632 – 9009 ) -9.07
… V809 Cep 2013.2 D(36) 11.18 $\pm$ 0.10 Fe II 500 … DISC 6162 ( 5051 – 10594
) … … V962 Cep 2014.3 S(42) 11.00 $\pm$ 0.10 Fe II 2000 … DISC 5545 ( 4606 –
7262 ) -5.63 … HV Cet 2008.8 … $<$14.2 $\pm$ 0.20 Ne 2900 1.7718 DISC 380 (
260 – 881 ) … SubG, PreERise RR Cha 1953.3 … $<$6.7 $\pm$ 0.25 … … 0.1401 DISC
1860 ( 1615 – 2628 ) … Ecl X Cir 1927.0 … $<$6.1 $\pm$ 0.25 … 1420 0.15446
DISC 3267 ( 2144 – 5718 ) … Ecl AR Cir 1906.1 J(330) 8.29 $\pm$ 0.45 … …
0.2143 DISC 1456 ( 1306 – 1842 ) … … BY Cir 1995.1 P(124) 7.40 $\pm$ 0.10 Fe
II 1500 0.2816 DISC 2396 ( 2078 – 3347 ) … Ecl DD Cir 1999.6 P(16) 7.60 $\pm$
0.10 … … 0.09746 DISC 3244 ( 2410 – 5328 ) -6.26 InGap, Ecl, IP? DE Cir 2003.8
S(4) 7.70 $\pm$ 0.50 He/N 5100 … DISC 6153 ( 5236 – 8583 ) … … FM Cir 2018.1
J(85) 5.90 $\pm$ 0.20 Fe II 1500 0.14977 DISC 3245 ( 2751 – 5043 ) -7.37 …
V394 CrA RN P(5) 7.20 $\pm$ 0.10 … 4600 1.51568 BULGE 7662 ( 6931 – 8405 )
-7.84 SubG, Ecl, $\dot{P}$ V655 CrA 1967.5 … $<$7.7 $\pm$ 0.23 … … … BULGE
8212 ( 7529 – 8975 ) … … V693 CrA 1981.3 S(18) 7.00 $\pm$ 0.10 Ne 4500 … BULGE
8027 ( 7300 – 8733 ) -7.83 … T CrB RN S(6) 2.50 $\pm$ 0.10 … 4980 227.532 DISC
914 ( 892 – 938 ) -7.62 RG, PreERise, $\Delta P$, $\dot{P}$ AP Cru 1935.2 …
$<$9.9 $\pm$ 0.23 … … … DISC 5632 ( 4615 – 9793 ) … … CP Cru 1996.7 … $<$9.2
$\pm$ 0.20 He/N, Ne 2000 0.944 DISC 2402 ( 1949 – 3879 ) … SubG, Ecl V450 Cyg
1942.7 D(108) 7.80 $\pm$ 0.30 Fe II … … DISC 4587 ( 4077 – 5690 ) -6.78 … V465
Cyg 1948.4 … 9.49 $\pm$ 0.50 Fe II … … DISC 5487 ( 4207 – 8475 ) … … V476 Cyg
1920.6 D(16) 1.90 $\pm$ 0.10 Fe II … … DISC 1179 ( 1078 – 1377 ) -9.02 Shell
V1330 Cyg 1970.4 S $<$8.5 $\pm$ 0.23 … … 0.50 DISC 2883 ( 2557 – 3976 ) … …
V1500 Cyg 1975.7 S(4) 1.90 $\pm$ 0.10 Hybrid, Ne … 0.13962 DISC 1504 ( 1343 –
1823 ) -10.38 V1500, AP, PreERise, Sh V1668 Cyg 1978.7 S(26) 6.20 $\pm$ 0.10
Fe II, Ne 2400 0.1384 DISC 3836 ( 3144 – 5247 ) -7.90 Ecl V1819 Cyg 1986.6
J(181) 9.30 $\pm$ 0.10 Fe II 2742 … DISC 6428 ( 5219 – 8877 ) -6.29 Shell
V1974 Cyg 1992.1 P(43) 4.30 $\pm$ 0.10 Hybrid, Ne 2000 0.08126 DISC 1618 (
1510 – 1796 ) -7.55 InGap, V1500, Sh V2274 Cyg 2001.5 D(33) 11.50 $\pm$ 0.10
Fe II 950 … DISC 7227 ( 5755 – 10379 ) -6.92 … V2275 Cyg 2001.6 S(8) 6.90
$\pm$ 0.10 … 2100 0.31449 DISC 3302 ( 2771 – 4930 ) -8.79 … V2361 Cyg 2005.1
S(8) 10.20 $\pm$ 0.20 He/N 2200 … DISC 5492 ( 4393 – 8096 ) -7.22 … V2362 Cyg
2006.3 C(246) 8.10 $\pm$ 0.10 Fe II 1850 … DISC 5438 ( 4461 – 8717 ) -7.31 …
V2467 Cyg 2007.2 O(20) 7.40 $\pm$ 0.10 Fe II 950 0.15379 DISC 1836 ( 1637 –
2360 ) -8.26 … V2468 Cyg 2008.0 S(20) 7.60 $\pm$ 0.40 Hybrid 2100 0.14525 DISC
5983 ( 4719 – 9073 ) -8.70 … V2491 Cyg 2008.3 C(16) 7.50 $\pm$ 0.10 He/N 4860
… DISC 4786 ( 4101 – 6339 ) -6.61 IP? V2659 Cyg 2014.3 J(140) 9.30 $\pm$ 0.10
Fe II 1000 … DISC 5384 ( 4725 – 6780 ) -6.53 … V2891 Cyg 2019.8 J 14.30 $\pm$
0.20 Fe II 820 … DISC 6991 ( 4850 – 13752 ) … … Q Cyg 1876.9 S(11) 3.00 $\pm$
0.10 Fe II … 0.42036 DISC 663 ( 658 – 669 ) -6.91 … HR Del 1967.5 J(231) 3.60
$\pm$ 0.10 Fe II, Ne … 0.21416 DISC 897 ( 880 – 915 ) -6.50 $\Delta P$,
$\dot{P}$, Sh V339 Del 2013.7 PP(29) 4.80 $\pm$ 0.10 Fe II 1421 0.16294 DISC
1587 ( 1288 – 2925 ) -6.76 $\gamma$ KT Eri RN PP(14) 5.42 $\pm$ 0.02 He/N 3300
2.61595 DISC 4211 ( 3915 – 4677 ) -7.95 SubG, LAmpVar DM Gem 1903.2 S(22) 4.78
$\pm$ 0.21 … … … DISC 3289 ( 2868 – 4298 ) -8.15 … DN Gem 1912.2 P(35) 3.60
$\pm$ 0.10 Fe II … 0.12784 DISC 1381 ( 1300 – 1511 ) -7.63 … DQ Her 1934.9
D(100) 1.60 $\pm$ 0.10 Fe II, Ne … 0.19362 DISC 496 ( 492 – 500 ) -7.03 Ecl,
$\Delta P$, $\dot{P}$, IP, Sh V446 Her 1960.2 S(11) 2.52 $\pm$ 0.10 He/N …
0.207 DISC 1256 ( 1176 – 1386 ) -9.12 DN, Shell V533 Her 1963.1 S(43) 3.00
$\pm$ 0.10 Fe II … 0.147 DISC 1269 ( 1236 – 1307 ) -7.61 IP?, Sh, PreERise
V827 Her 1987.1 S(53) 7.50 $\pm$ 0.10 … … … DISC 2366 ( 1894 – 4325 ) … … V838
Her 1991.2 P(4) 5.30 $\pm$ 0.10 He/N, Ne 5000 0.29764 DISC 3128 ( 2657 – 4164
) -8.73 Ecl V1674 Her 2021.5 S(2) 6.20 $\pm$ 0.20 … … 0.15302 DISC 3216 ( 2472
– 5359 ) … IP, $\gamma$ CP Lac 1936.5 S(9) 2.00 $\pm$ 0.10 Hybrid … 0.14514
DISC 1164 ( 1125 – 1205 ) -9.17 Shell DI Lac 1911.0 S(43) 4.23 $\pm$ 0.40 Fe
II … … DISC 1729 ( 1682 – 1786 ) -7.77 … DK Lac 1950.1 J(202) 5.90 $\pm$ 0.10
Fe II … … DISC 2986 ( 2700 – 3604 ) -7.34 Shell HY Lup 1993.7 S(26) 7.70 $\pm$
0.50 Fe II 2700 … DISC 2281 ( 1826 – 3446 ) -5.08 … PR Lup 2011.7 J(40) 8.60
$\pm$ 0.20 Fe II 1700 … DISC 6715 ( 5577 – 8851 ) -7.40 … V407 Lup 2016.8 S(8)
6.40 $\pm$ 0.20 Fe II 3700 3.62 DISC 2900 ( 2281 – 4724 ) -6.78 SubG, IP?,
NonOrbP, $\gamma$ V408 Lup 2018.5 J(87) 8.98 $\pm$ 0.10 Fe II 1300 … DISC 4550
( 3307 – 7045 ) … … HR Lyr 1919.9 … 6.50 $\pm$ 0.50 Fe II … 0.90578 DISC 4704
( 4305 – 5447 ) -7.36 SubG BT Mon 1940.0 F(182) 8.10 $\pm$ 0.10 … 2100 0.33381
DISC 1580 ( 1513 – 1668 ) -3.64 Ecl, $\Delta P$, $\dot{P}$, Sh GI Mon 1918.1
S(23) 5.39 $\pm$ 0.50 He/N … 0.44706 DISC 3357 ( 3038 – 4076 ) -7.55 Ecl, DN,
IP? KT Mon 1942.9 S(40) 9.64 $\pm$ 0.41 He/N … … DISC 5048 ( 3793 – 8343 ) … …
V959 Mon 2012.7 S $<$9.4 $\pm$ 0.20 Ne … 0.29585 DISC 2902 ( 2485 – 4070 ) …
$\gamma$ GQ Mus 1983.0 P(108) 7.80 $\pm$ 0.30 … 1000 0.05937 DISC 4043 ( 3248
– 6447 ) -6.63 $<$Gap, V1500 LZ Mus 1999.0 P(12) 8.50 $\pm$ 0.10 … … … DISC
6749 ( 5751 – 9332 ) -8.59 … QY Mus 2008.7 D(100) 8.60 $\pm$ 0.20 Fe II 1550
0.90114 DISC 4570 ( 3886 – 6053 ) -6.53 SubG, NonOrbP V357 Mus 2018.1 D(32)
6.70 $\pm$ 0.10 … … 0.15516 DISC 2991 ( 2544 – 5074 ) … … IL Nor 1893.5 S 6.34
$\pm$ 0.15 … … 0.06709 DISC 3318 ( 2404 – 5886 ) … $<$Gap

Table 8: continued

Distances and Properties of All 402 Known Galactic Novae  Nova Year
LC($t_{3}$) $V_{peak}$ Spec. FWHM $P$ Pop. $D$ (68% range) $M_{V}$ Propertiesa
IM Nor RN P(80) 8.50 $\pm$ 0.10 … 2380 0.20717 DISC 4312 ( 3461 – 6326 ) -7.15
Ecl, $\dot{P}$ V341 Nor 1983.7 S(14) 9.40 $\pm$ 0.50 … 3000 … DISC 7436 ( 5476
– 11209 ) … … V382 Nor 2005.2 S(18) 8.70 $\pm$ 0.40 Fe II 1850 … DISC 5615 (
4341 – 8119 ) -7.68 … V390 Nor 2007.5 J 9.10 $\pm$ 0.30 Fe II … 0.17133 DISC
4174 ( 3337 – 6010 ) -6.79 … V555 Nor 2016.3 S(110) 12.70 $\pm$ 0.40 He/N 2140
… DISC 7561 ( 5476 – 11720 ) … … V556 Nor 2018.9 S(9) 10.10 $\pm$ 0.40 Fe II
2800 … DISC 5840 ( 4028 – 9161 ) … … RS Oph RN P(14) 4.80 $\pm$ 0.10 … 3930
453.6 DISC 2710 ( 2575 – 2908 ) -9.63 RG, $\gamma$, PostEdip BB Oph 1897.4 …
$<$11.3 $\pm$ 0.20 … … … bulge 8142 ( 7396 – 8883 ) … … V553 Oph 1940.6 …
11.06 $\pm$ 0.58 … … … BULGE 8124 ( 7394 – 8871 ) … … V794 Oph 1939.5 J(220)
10.69 $\pm$ 0.41 … … 18 BULGE 8463 ( 7765 – 9179 ) -6.74 RG V840 Oph 1917.3 …
6.04 $\pm$ 0.52 … … … bulge 7975 ( 7231 – 8720 ) -9.55 … V841 Oph 1848.3
J(130) 4.30 $\pm$ 0.40 … … 0.60130 DISC 843 ( 831 – 857 ) -6.57 SubG V849 Oph
1919.6 F(270) 7.60 $\pm$ 0.10 Fe II, Ne … 0.17276 DISC 3637 ( 3007 – 5127 )
-5.51 Ecl V906 Oph 1952.6 … 8.54 $\pm$ 0.39 Fe II 2000 … bulge 8079 ( 7344 –
8826 ) -8.01 … V908 Oph 1954.5 … $<$7.9 $\pm$ 0.36 … … … disc? 4931 ( 3139 –
7833 ) … … V972 Oph 1957.7 J(176) 7.39 $\pm$ 0.23 … … 0.27964 DISC 778 ( 691 –
1111 ) -3.62 … V1012 Oph 1961.3 … $<$12.9 $\pm$ 0.45 … … … BULGE 8124 ( 7396 –
8883 ) … … V2024 Oph 1967.5 … $<$10.2 $\pm$ 0.36 … … … bulge 8137 ( 7396 –
8883 ) … … V2104 Oph 1976.7 … $<$8.8 $\pm$ 0.20 He/N, Ne 870 … DISC 1691 (
1315 – 3115 ) … … V2109 Oph 1969.5 … $<$9.8 $\pm$ 0.36 … … 1.32379 BULGE 8138
( 7398 – 8873 ) … SubG, DN V2214 Oph 1988.3 S(89) 8.50 $\pm$ 0.10 Fe II, Ne
1025 0.11752 BULGE 7990 ( 7328 – 8708 ) -8.03 … V2264 Oph 1991.3 S(30) 10.00
$\pm$ 0.10 Fe II, Ne 2300 … bulge 8155 ( 7417 – 8893 ) -6.73 … V2290 Oph
1991.3 … $<$9.3 $\pm$ 0.20 … … … bulge 8149 ( 7395 – 8882 ) … … V2295 Oph
1993.3 F(16) 9.30 $\pm$ 0.10 Fe II … … bulge 8097 ( 7366 – 8844 ) -7.57 …
V2313 Oph 1994.4 S(17) 7.50 $\pm$ 0.10 Fe II 2500 … disc? 2738 ( 2126 – 5592 )
… … V2487 Oph RN P(8) 9.50 $\pm$ 0.10 … 10000 1.24 BULGE 7539 ( 6812 – 8282 )
-6.44 SubG, Superflare V2540 Oph 2002.1 J(115) 8.10 $\pm$ 0.10 … … 0.28478
BULGE 8117 ( 7389 – 8859 ) -7.66 Ecl V2573 Oph 2003.5 D(81) 10.60 $\pm$ 0.10
Fe II 1300 … bulge 8149 ( 7416 – 8890 ) -6.81 … V2574 Oph 2004.3 S(41) 10.20
$\pm$ 0.30 Fe II 1500 0.13509 BULGE 8157 ( 7415 – 8888 ) -7.09 NonOrbP V2575
Oph 2006.1 J(66) 11.00 $\pm$ 0.40 Fe II 560 … DISC 4055 ( 3307 – 5480 ) -6.38
… V2576 Oph 2006.3 S(29) 9.20 $\pm$ 0.40 Fe II 1470 … DISC 2968 ( 2341 – 4798
) -5.08 … V2615 Oph 2007.2 S(48) 8.50 $\pm$ 0.30 Fe II 800 0.27234 DISC 2529 (
2018 – 4398 ) … … V2670 Oph 2008.4 J(37) 10.00 $\pm$ 0.40 Fe II 600 … BULGE
7825 ( 7111 – 8560 ) -7.26 … V2671 Oph 2008.4 … 11.10 $\pm$ 0.10 Fe II 1210 …
BULGE 8150 ( 7432 – 8905 ) -6.56 … V2672 Oph 2009.6 S(6) 10.10 $\pm$ 0.40 He/N
8000 … BULGE 7703 ( 6967 – 8447 ) -9.29 … V2673 Oph 2010.1 S(28) 8.30 $\pm$
0.10 Fe II … … bulge 8042 ( 7296 – 8778 ) -8.43 … V2674 Oph 2010.2 S(31) 9.25
$\pm$ 0.10 Fe II 1650 1.30207 DISC 3204 ( 2519 – 5295 ) … SubG, Ecl V2676 Oph
2012.3 D(68) 10.60 $\pm$ 0.10 Fe II 950 … BULGE 8149 ( 7438 – 8864 ) -6.78 …
V2677 Oph 2012.5 S(13) 10.80 $\pm$ 0.20 Fe II 3000 0.34430 bulge 8174 ( 7463 –
8888 ) -7.79 … V2944 Oph 2015.3 J(145) 9.00 $\pm$ 0.20 Hybrid 1050 … BULGE
8285 ( 7626 – 8988 ) -7.45 … V2949 Oph 2015.9 J 11.90 $\pm$ 0.40 Fe II 900 …
BULGE 8365 ( 7668 – 9101 ) … … V3661 Oph 2016.3 S(5.7) 10.79 $\pm$ 0.20 Fe II
1200 … bulge 7873 ( 7126 – 8624 ) -11.13 … V3662 Oph 2017.4 … $<$13.6 $\pm$
0.20 Fe II 1400 … bulge 8125 ( 7396 – 8883 ) … … V3663 Oph 2017.9 … $<$9.4
$\pm$ 0.20 Fe II 2500 … bulge 8081 ( 7344 – 8827 ) … … V3664 Oph 2018.2 …
$<$12.8 $\pm$ 0.20 Fe II … 2250 bulge 8129 ( 7376 – 8867 ) … RG V3665 Oph
2018.3 S(61) 9.30 $\pm$ 0.50 Fe II 1400 … bulge 8136 ( 7406 – 8881 ) -6.96 …
V3666 Oph 2018.7 S(57) 9.50 $\pm$ 0.20 Fe II 930 … DISC 1701 ( 1605 – 5260 ) …
… V3701 Oph 2010.8 … $<$11.2 $\pm$ 0.20 … … … bulge 8104 ( 7365 – 8848 ) … …
V3730 Oph 2019.8 … $<$12.3 $\pm$ 0.20 … 3000 … BULGE 8072 ( 7336 – 8821 ) … …
V3731 Oph 2019.6 … $<$13.3 $\pm$ 0.20 He/N 2600 … bulge 8129 ( 7378 – 8857 ) …
… V3732 Oph 2021.2 … $<$15.8 $\pm$ 0.20 He/N 1800 0.94004 bulge 8136 ( 7396 –
8883 ) … SubG Nova 1938 Oph 1938.5 … $<$15.1 $\pm$ 0.23 … … … GlobC 8652 (
8122 – 9157 ) … in M14 V2860 Ori 2019.7 P(13) 10.00 $\pm$ 0.20 He/N 4000
0.42258 DISC 5969 ( 4698 – 9275 ) -5.43 … V Per 1888.0 … $<$8.7 $\pm$ 0.25 … …
0.10712 DISC 3152 ( 2687 – 5304 ) … InGap, Ecl GK Per 1901.1 O(13) 0.20 $\pm$
0.10 Fe II, Ne … 1.99680 DISC 434 ( 427 – 442 ) -9.04 SubG, DN, IP, Sh V392
Per 2018.4 P(11) 6.20 $\pm$ 0.10 Ne … 3.21997 DISC 3402 ( 3071 – 4178 ) -10.12
SubG, DN, $\gamma$ V400 Per 1974.9 J(110) 8.00 $\pm$ 0.40 He/N … 0.82639 DISC
3222 ( 2543 – 4946 ) -5.04 SubG V1112 Per 2021.0 D(34) 8.20 $\pm$ 0.10 Fe II
1550 … DISC 3945 ( 3055 – 6706 ) -6.80 … RR Pic 1925.4 J(122) 1.00 $\pm$ 0.10
Fe II … 0.14502 DISC 501 ( 496 – 507 ) -7.69 $\Delta P$, $\dot{P}$, Sh CP Pup
1942.9 P(8) 0.70 $\pm$ 0.10 He/N … 0.06126 DISC 783 ( 770 – 793 ) -9.39
$<$Gap, V1500, Sh DY Pup 1902.9 … $<$6.7 $\pm$ 0.23 … … 0.13952 DISC 3585 (
2791 – 6051 ) … Ecl HS Pup 1963.9 S(65) 7.37 $\pm$ 0.23 … … 0.17864 DISC 4637
( 3909 – 7380 ) -7.57 … HZ Pup 1963.0 J(70) 7.24 $\pm$ 0.18 … … 0.212 DISC
2899 ( 2615 – 3639 ) -6.16 IP

Table 9: continued

Distances and Properties of All 402 Known Galactic Novae  Nova Year
LC($t_{3}$) $V_{peak}$ Spec. FWHM $P$ Pop. $D$ (68% range) $M_{V}$ Propertiesa
V351 Pup 1992.0 P(26) 6.40 $\pm$ 0.10 Fe II, Ne … 0.1182 DISC 3869 ( 3077 –
5996 ) -8.55 Shell V445 Pup 2000.9 D(240) 8.60 $\pm$ 0.10 Helium … … DISC 6272
( 5026 – 9026 ) -6.97 Shell V574 Pup 2004.9 S(27) 7.00 $\pm$ 0.10 Fe II, Ne
2830 … DISC 4567 ( 3744 – 7174 ) -7.85 … V597 Pup 2007.6 S(6) 6.20 $\pm$ 0.50
Hybrid 1800 0.11119 DISC 5851 ( 4682 – 9384 ) -8.57 Ecl, IP? V598 Pup 2007.6 …
$<$10.2 $\pm$ 0.20 He/N 2100 0.16287 DISC 1844 ( 1755 – 1965 ) … NonOrbP T Pyx
RN P(62) 6.40 $\pm$ 0.10 Hybrid 5350 0.07623 DISC 3599 ( 3369 – 3931 ) -7.16
InGap, Ecl, $\Delta P$, $\dot{P}$, PreERise, V1500, Sh YZ Ret 2020.6 P(22)
3.70 $\pm$ 0.40 He/N, Ne 2500 0.13245 DISC 2388 ( 2234 – 2636 ) -8.25 NonOrbP,
$\gamma$ WY Sge 1783.6 … $<$6 $\pm$ 0.20 … … 0.15363 DISC 1069 ( 983 – 1264 )
… Ecl, DN? HS Sge 1977.0 P(21) 7.20 $\pm$ 0.10 … 1600 … DISC 3193 ( 2403 –
6432 ) … … AT Sgr 1900.7 … $<$9.4 $\pm$ 1.12 … … … disc? 7776 ( 4602 – 10006 )
… … BS Sgr 1917.5 … $<$8.8 $\pm$ 0.23 … 640 … BULGE 8216 ( 7530 – 8937 ) … …
FL Sgr 1924.4 … $<$7.9 $\pm$ 0.25 … … … bulge 8094 ( 7364 – 8842 ) … … FM Sgr
1926.5 … $<$7.9 $\pm$ 0.29 … … … DISC 653 ( 740 – 6269 ) … … GR Sgr 1924.3 …
$<$11.0 $\pm$ 0.23 … … 29.4956 DISC 1406 ( 1325 – 1530 ) … RG HS Sgr 1900.7 …
$<$10.8 $\pm$ 0.29 … … … BULGE 8143 ( 7391 – 8879 ) … … KY Sgr 1926.4 S(109)
9.94 $\pm$ 0.36 … … 294 bulge? 7801 ( 7084 – 8534 ) -6.23 RG V363 Sgr 1927.7 …
$<$8.6 $\pm$ 0.21 … 685 0.12607 BULGE 8141 ( 7395 – 8884 ) … … V441 Sgr 1930.7
… $<$8.2 $\pm$ 0.25 … … … bulge 8098 ( 7364 – 8841 ) … … V630 Sgr 1936.8 S(11)
3.49 $\pm$ 0.29 Ne … 0.11793 disc? 3595 ( 3068 – 5469 ) -10.53 Ecl V726 Sgr
1936.3 S(95) 10.04 $\pm$ 0.34 Ne … 0.82281 BULGE 8245 ( 7511 – 8976 ) -5.63
SubG V732 Sgr 1936.4 D(75) 6.40 $\pm$ 0.10 … … … DISC 3251 ( 2551 – 5741 ) … …
V787 Sgr 1937.4 … $<$9.2 $\pm$ 0.25 … … … BULGE 8186 ( 7456 – 8933 ) … … V909
Sgr 1941.5 … 6.49 $\pm$ 0.52 Ne … 0.14286 bulge 8036 ( 7291 – 8776 ) -8.66 Ecl
V927 Sgr 1944.3 … $<$7.6 $\pm$ 0.23 … … … BULGE 8065 ( 7323 – 8803 ) … … V928
Sgr 1947.4 … $<$8.4 $\pm$ 0.23 Fe II 690 … bulge 8107 ( 7378 – 8854 ) … … V990
Sgr 1936.7 S(24) 10.09 $\pm$ 0.50 … … … BULGE 8224 ( 7507 – 8953 ) … … V999
Sgr 1910.2 J(160) 7.41 $\pm$ 0.29 … 595 0.15184 DISC 3122 ( 2780 – 4905 )
-6.86 … V1012 Sgr 1914.6 … 7.59 $\pm$ 0.54 … … … BULGE 8072 ( 7323 – 8805 )
-7.87 … V1014 Sgr 1901.4 … 10.07 $\pm$ 0.54 … … … bulge 8142 ( 7419 – 8894 )
-6.72 … V1015 Sgr 1905.6 … $<$6.7 $\pm$ 0.25 … … … BULGE 8012 ( 7267 – 8751 )
… … V1016 Sgr 1899.8 … $<$8.0 $\pm$ 0.23 … … 13.4 DISC 2666 ( 2538 – 2844 ) …
RG, NonOrbP, IP? V1017 Sgr 1919.2 … $<$6.8 $\pm$ 0.23 … … 5.78629 DISC 1226 (
1194 – 1264 ) … SubG, DN, $\Delta P$, $\dot{P}$ V1059 Sgr 1898.2 S(26) 4.54
$\pm$ 0.62 … … 0.2861 DISC 2694 ( 2379 – 3708 ) -8.39 … V1148 Sgr 1943.6 …
$<$7.3 $\pm$ 0.29 … … … DISC 2148 ( 2009 – 2377 ) … … V1149 Sgr 1945.1 …
$<$7.0 $\pm$ 0.23 … 960 … BULGE 8080 ( 7343 – 8816 ) … … V1150 Sgr 1946.4 …
$<$12.6 $\pm$ 0.25 … … … BULGE 8126 ( 7396 – 8883 ) … … V1151 Sgr 1947.3 …
$<$10.2 $\pm$ 0.29 … … … bulge 8145 ( 7394 – 8878 ) … … V1172 Sgr 1951.2 …
$<$8.5 $\pm$ 0.25 … 2500 255 BULGE 7512 ( 6825 – 8254 ) … RG V1174 Sgr 1952.2
… $<$11.2 $\pm$ 0.29 … … 0.30905 bulge 8141 ( 7396 – 8883 ) … … V1175 Sgr
1952.1 … $<$6.7 $\pm$ 0.23 … … … disc? 1275 ( 1339 – 5400 ) … … V1275 Sgr
1954.5 … $<$6.6 $\pm$ 0.25 … 1000 … BULGE 7958 ( 7235 – 8695 ) … … V1310 Sgr
1935.4 F(390) 11.44 $\pm$ 0.15 … … … BULGE 8375 ( 7647 – 9102 ) -3.64 … V1572
Sgr 1955.1 … $<$10.3 $\pm$ 0.25 … … … bulge 8136 ( 7396 – 8883 ) … … V1583 Sgr
1928.6 S(37) 8.29 $\pm$ 0.36 … 780 … BULGE 8098 ( 7360 – 8841 ) … … V1944 Sgr
1960.4 … $<$10.9 $\pm$ 0.54 … … … disc? 7766 ( 4786 – 9653 ) … … V2415 Sgr
1951.7 … $<$12.0 $\pm$ 0.36 … … … bulge 8141 ( 7396 – 8883 ) … … V2572 Sgr
1969.5 S(44) 6.26 $\pm$ 0.50 … … 0.15704 BULGE 8065 ( 7329 – 8802 ) -8.68 …
V3645 Sgr 1970.6 … $<$12.1 $\pm$ 0.23 … … 39.5 BULGE 7581 ( 6847 – 8342 ) … RG
V3888 Sgr 1974.8 … $<$9.0 $\pm$ 0.20 Fe II … … BULGE 7696 ( 6955 – 8432 ) … …
V3889 Sgr 1975.5 … $<$8.4 $\pm$ 0.20 … … … BULGE 8094 ( 7363 – 8837 ) … …
V3890 Sgr RN S(14) 8.10 $\pm$ 0.10 Hybrid 2140 747.6 BULGE 8546 ( 8097 – 9058
) -8.39 RG, $\gamma$ V3964 Sgr 1975.4 … $<$8.8 $\pm$ 0.29 Fe II 1320 … BULGE
8129 ( 7388 – 8862 ) … … V4021 Sgr 1977.2 P(215) 8.90 $\pm$ 0.10 … … … BULGE
8177 ( 7439 – 8909 ) -6.59 … V4027 Sgr 1968.4 … $<$10.3 $\pm$ 0.29 Fe II 2900
… BULGE 8353 ( 7648 – 9085 ) … … V4049 Sgr 1978.2 … $<$12.0 $\pm$ 0.20 Fe II …
… BULGE 8135 ( 7396 – 8883 ) … … V4065 Sgr 1980.8 … $<$9.0 $\pm$ 0.20 … … …
BULGE 7863 ( 7219 – 8561 ) … … V4077 Sgr 1982.8 J 8.00 $\pm$ 0.40 Fe II … …
BULGE 7610 ( 6864 – 8351 ) -7.40 … V4092 Sgr 1984.7 … $<$10.5 $\pm$ 0.20 … … …
bulge 8115 ( 7377 – 8857 ) … … V4121 Sgr 1983.1 … $<$9.5 $\pm$ 0.20 … … …
BULGE 8135 ( 7396 – 8883 ) … … V4135 Sgr 1987.4 … 10.40 $\pm$ 0.40 … 1000 …
BULGE 8178 ( 7454 – 8925 ) -6.33 … V4157 Sgr 1992.1 S(7) 7.00 $\pm$ 0.50 Fe II
1800 … bulge 7946 ( 7201 – 8694 ) -10.29 … V4160 Sgr 1991.6 S(3) 7.00 $\pm$
0.10 He/N, Ne 4500 … DISC 2602 ( 2062 – 4091 ) -6.07 …

Table 10: continued

Distances and Properties of All 402 Known Galactic Novae  Nova Year
LC($t_{3}$) $V_{peak}$ Spec. FWHM $P$ Pop. $D$ (68% range) $M_{V}$ Propertiesa
V4160 Sgr 1991.6 S(3) 7.00 $\pm$ 0.10 He/N, Ne 4500 … DISC 2602 ( 2062 – 4091
) -6.07 … V4169 Sgr 1992.5 S(36) 7.90 $\pm$ 0.10 Fe II … … DISC 2939 ( 2322 –
4561 ) -5.49 … V4171 Sgr 1992.8 S(20) 6.60 $\pm$ 0.20 Fe II 1200 … bulge 7946
( 7206 – 8697 ) -9.76 … V4327 Sgr 1993.6 S(30) 8.10 $\pm$ 0.30 Hybrid 2400 …
bulge 8092 ( 7359 – 8837 ) -7.62 … V4338 Sgr 1990.1 … 8.00 $\pm$ 0.50 … 400
29.48192 BULGE 8117 ( 7399 – 8853 ) -8.41 RG V4361 Sgr 1996.5 … $<$10.3 $\pm$
0.20 Fe II … … DISC 6845 ( 4332 – 9474 ) … … V4362 Sgr 1994.4 D(121) 7.80
$\pm$ 0.20 Fe II 450 … bulge 8074 ( 7344 – 8828 ) … … V4444 Sgr 1999.3 S(9)
7.60 $\pm$ 0.10 Fe II 800 … BULGE 7595 ( 6870 – 8360 ) -8.20 … V4579 Sgr
1986.8 … $<$10.4 $\pm$ 0.20 … … 0.15356 DISC 1372 ( 1304 – 1467 ) … Ecl V4633
Sgr 1998.2 P(44) 7.40 $\pm$ 0.10 Fe II 1700 0.12557 disc 2426 ( 1917 – 3857 )
-5.33 V1500 V4642 Sgr 2000.1 S(60) 10.40 $\pm$ 0.40 Fe II 1530 … bulge 8067 (
7324 – 8810 ) … … V4643 Sgr 2001.1 S(6) 7.70 $\pm$ 0.10 … 4700 … DISC 5867 (
4629 – 7965 ) -10.70 … V4739 Sgr 2001.7 S(3) 7.20 $\pm$ 0.10 He/N 5510 … bulge
8002 ( 7267 – 8751 ) -8.74 … V4740 Sgr 2001.7 S(33) 6.70 $\pm$ 0.10 Fe II … …
BULGE 8033 ( 7288 – 8768 ) -8.91 … V4741 Sgr 2002.3 S(13) 9.20 $\pm$ 0.40 Fe
II 2800 … bulge 8066 ( 7312 – 8795 ) -8.46 … V4742 Sgr 2002.7 S(23) 7.90 $\pm$
0.10 Fe II 2500 0.13362 DISC 3593 ( 2832 – 6016 ) … Ecl V4743 Sgr 2002.7 S(12)
5.50 $\pm$ 0.20 Fe II, Ne 2400 0.2799 DISC 3717 ( 3253 – 4913 ) -8.13 IP V4744
Sgr 2002.8 … $<$9.7 $\pm$ 0.20 Fe II 1600 … DISC 813 ( 633 – 1609 ) … … V4745
Sgr 2003.3 J(190) 7.30 $\pm$ 0.10 Fe II 1350 0.20782 BULGE 8091 ( 7362 – 8834
) -7.86 IP? V5113 Sgr 2003.7 J(48) 9.00 $\pm$ 0.30 Fe II 550 0.15002 bulge
8200 ( 7462 – 8932 ) -6.19 … V5114 Sgr 2004.2 S(21) 8.10 $\pm$ 0.10 Fe II 2000
… bulge 7959 ( 7209 – 8702 ) -8.26 … V5115 Sgr 2005.2 S(13) 7.90 $\pm$ 0.10
He/N 1300 … bulge 7749 ( 7014 – 8490 ) -8.10 … V5116 Sgr 2005.5 S(26) 7.60
$\pm$ 0.10 Fe II 970 0.12374 bulge 7573 ( 6837 – 8325 ) -7.51 Ecl V5117 Sgr
2006.1 S(23) 7.40 $\pm$ 0.30 Fe II 1600 … disc? 2350 ( 1856 – 3745 ) -5.70 …
V5558 Sgr 2007.3 J(157) 6.50 $\pm$ 0.10 Hybrid 1000 0.18581 DISC 2151 ( 2046 –
2319 ) -7.64 … V5579 Sgr 2008.3 D(13) 6.70 $\pm$ 0.10 Fe II 1500 … BULGE 7945
( 7210 – 8694 ) -10.03 … V5580 Sgr 2008.9 … $<$7.8 $\pm$ 0.20 … 2500 34 BULGE
8143 ( 7420 – 8887 ) … RG V5581 Sgr 2009.3 … 11.70 $\pm$ 0.20 Fe II 2600 1660
BULGE 8147 ( 7418 – 8886 ) … RG V5582 Sgr 2009.1 J(90) 10.90 $\pm$ 0.30 He/N …
0.15660 BULGE 8227 ( 7497 – 8963 ) -5.75 … V5583 Sgr 2009.6 S(7) 7.00 $\pm$
0.20 He/N 2300 … DISC 2383 ( 2142 – 3066 ) -5.94 … V5584 Sgr 2009.8 … 9.50
$\pm$ 0.20 Fe II 600 … BULGE 8090 ( 7391 – 8821 ) -7.83 … V5585 Sgr 2010.1
O(25) 9.00 $\pm$ 0.20 Fe II … 0.13753 BULGE 8312 ( 7613 – 9029 ) -7.12 Ecl
V5586 Sgr 2010.4 … 11.10 $\pm$ 0.20 … … … DISC 5195 ( 3856 – 7748 ) … … V5587
Sgr 2011.2 C 11.20 $\pm$ 0.40 … 1300 … bulge 8152 ( 7414 – 8890 ) -6.46
PreERise V5588 Sgr 2011.3 O(77) 11.30 $\pm$ 0.20 Hybrid 900 0.21432 bulge 7784
( 7052 – 8529 ) -7.34 … V5589 Sgr 2012.4 S(13) 8.80 $\pm$ 0.10 Hybrid 5700
1.5923 bulge 7819 ( 7078 – 8550 ) -7.68 SubG, Ecl V5591 Sgr 2012.6 S(8) 9.60
$\pm$ 0.20 He/N 4200 … bulge 7969 ( 7225 – 8716 ) -9.37 … V5592 Sgr 2012.6
D(28) 7.90 $\pm$ 0.30 Fe II 1700 … BULGE 8192 ( 7500 – 8919 ) -8.09 … V5593
Sgr 2012.6 J(82) 11.00 $\pm$ 0.10 Fe II 940 … BULGE 8092 ( 7358 – 8830 ) -8.59
… V5627 Sgr 1991 … $<$15.1 $\pm$ 0.20 … … 0.11716 disc? 2829 ( 2783 – 8097 ) …
… V5666 Sgr 2014.2 J(201) 9.90 $\pm$ 0.10 … … … BULGE 8010 ( 7315 – 8730 )
-6.57 … V5667 Sgr 2015.2 J(106) 9.10 $\pm$ 0.10 Fe II 300 … BULGE 7694 ( 7009
– 8411 ) -7.25 … V5668 Sgr 2015.3 D(78) 4.30 $\pm$ 0.10 Fe II 2800 … DISC 1290
( 1045 – 1875 ) -6.56 … V5669 Sgr 2015.8 S 9.00 $\pm$ 0.10 Fe II 2000 … BULGE
8304 ( 7603 – 9037 ) -7.46 … V5850 Sgr 2015.9 … $<$11.3 $\pm$ 0.20 … … … bulge
8097 ( 7357 – 8838 ) … … V5853 Sgr 2016.7 S(63) 11.50 $\pm$ 0.10 Fe II … …
bulge 8016 ( 7276 – 8761 ) -8.91 … V5854 Sgr 2016.6 … $<$11.1 $\pm$ 0.20 …
2100 … bulge 8087 ( 7349 – 8838 ) … … V5855 Sgr 2016.9 J(19) 7.80 $\pm$ 0.10
Fe II … … bulge 8049 ( 7312 – 8794 ) -8.28 … V5856 Sgr 2016.9 P(14) 5.90 $\pm$
0.10 Fe II … … DISC 3179 ( 2327 – 6029 ) … $\gamma$, V1500 V5857 Sgr 2018.4 …
$<$10.6 $\pm$ 0.20 Fe II 387 … bulge 8099 ( 7355 – 8844 ) … … V5914 Sgr 2006.1
C $<$13.2 $\pm$ 0.20 … … 0.82184 bulge 8144 ( 7396 – 8883 ) … SubG V5926 Sgr
2013.3 S $<$16.4 $\pm$ 0.20 … … … bulge 8131 ( 7390 – 8877 ) … … V5980 Sgr
2010.1 … $<$12.1 $\pm$ 0.20 … … … BULGE 8119 ( 7386 – 8875 ) … … V6345 Sgr
2010.3 … $<$11.0 $\pm$ 0.20 Fe II … … bulge 8147 ( 7396 – 8883 ) … … V6566 Sgr
2020.2 … $<$11.1 $\pm$ 0.20 Fe II 1500 … BULGE 8156 ( 7428 – 8892 ) … … V6567
Sgr 2020.5 J 12.50 $\pm$ 0.10 Fe II … … BULGE 8166 ( 7433 – 8905 ) -6.56 …
V6568 Sgr 2020.6 … $<$9.9 $\pm$ 0.20 Fe II 4500 … bulge 8150 ( 7392 – 8874 ) …
… V6593 Sgr 2020.8 … $<$11.1 $\pm$ 0.20 Fe II … … bulge 8098 ( 7363 – 8841 ) …
… V6594 Sgr 2021.3 D(38) 9.50 $\pm$ 0.10 Fe II 1370 … BULGE 8231 ( 7499 – 8963
) -6.01 … V6595 Sgr 2021.3 S(15) 7.50 $\pm$ 0.10 Fe II, Ne … … BULGE 7991 (
7250 – 8736 ) -9.03 … T Sco 1860.4 S(18) 6.80 $\pm$ 0.40 … … … GlobC 8845 (
8317 – 9453 ) -8.71 in M80 U Sco RN PP(3) 7.50 $\pm$ 0.10 He/N, Ne 5700
1.23055 DISC 6258 ( 5421 – 7428 ) -7.10 SubG, Ecl, $\Delta P$, $\dot{P}$ KP
Sco 1928.5 … 8.59 $\pm$ 0.43 … … … bulge 8085 ( 7344 – 8826 ) … … V696 Sco
1944.3 … $<$7.1 $\pm$ 0.25 … … … DISC 2322 ( 2119 – 2781 ) … …

Table 11: continued

Distances and Properties of All 402 Known Galactic Novae  Nova Year
LC($t_{3}$) $V_{peak}$ Spec. FWHM $P$ Pop. $D$ (68% range) $M_{V}$ Propertiesa
V697 Sco 1941.2 … $<$9.8 $\pm$ 0.25 … 1550 1.26716 DISC 870 ( 780 – 1257 ) …
SubG, Ecl V707 Sco 1922.5 … 9.14 $\pm$ 0.45 … … … bulge 8119 ( 7377 – 8855 )
-7.42 … V711 Sco 1906.3 S 9.08 $\pm$ 0.18 … … … bulge 8128 ( 7400 – 8875 )
-7.05 … V719 Sco 1950.5 … 8.55 $\pm$ 0.32 Fe II 1800 0.43639 bulge 8057 ( 7315
– 8801 ) … … V720 Sco 1950.6 … $<$6.9 $\pm$ 0.25 Fe II 1800 … BULGE 7997 (
7256 – 8743 ) … … V721 Sco 1950.7 … $<$9.2 $\pm$ 0.29 … … … DISC 1857 ( 1748 –
2028 ) … … V722 Sco 1952.2 … $<$8.7 $\pm$ 0.29 … … … bulge 8063 ( 7331 – 8812
) … … V723 Sco 1952.6 S(23) 8.09 $\pm$ 0.43 … … 7.2 bulge 8070 ( 7319 – 8805 )
… SubG V728 Sco 1862.8 … $<$5 $\pm$ 0.20 … … 0.13834 DISC 1030 ( 930 – 1309 )
… Ecl V745 Sco RN P(9) 9.40 $\pm$ 0.10 He/N 3600 2440 BULGE 8016 ( 7431 – 8640
) -8.22 RG, $\gamma$ V825 Sco 1964.4 … $<$10.9 $\pm$ 0.36 Ne … 0.19166 BULGE
8184 ( 7456 – 8933 ) … Ecl V902 Sco 1949.4 … $<$9.8 $\pm$ 0.36 … … … BULGE
8096 ( 7363 – 8840 ) … … V960 Sco 1985.7 … $<$10.5 $\pm$ 0.20 Fe II … … BULGE
8193 ( 7454 – 8920 ) … … V977 Sco 1989.6 … $<$10.4 $\pm$ 0.20 Fe II, Ne … 26.2
DISC 467 ( 428 – 550 ) … RG V992 Sco 1992.4 D(120) 7.70 $\pm$ 0.10 Fe II 800
0.1536 DISC 1815 ( 1622 – 2392 ) … … V1141 Sco 1997.4 S(9) 8.50 $\pm$ 0.50 Fe
II 3200 … bulge 8096 ( 7358 – 8838 ) -7.75 … V1142 Sco 1998.8 S(22) 6.90 $\pm$
0.40 … 3800 … bulge 7985 ( 7257 – 8745 ) -9.32 … V1178 Sco 2001.4 … 10.20
$\pm$ 0.20 Fe II 1300 … BULGE 8162 ( 7428 – 8900 ) -6.75 … V1186 Sco 2004.5
J(62) 9.70 $\pm$ 0.10 Fe II 500 0.20297 DISC 4099 ( 2634 – 7425 ) … Ecl V1187
Sco 2004.6 S(17) 9.80 $\pm$ 0.10 Fe II, Ne 3000 … DISC 4625 ( 3772 – 7155 ) …
… V1188 Sco 2005.6 S(23) 8.90 $\pm$ 0.10 Fe II 1730 … bulge 8049 ( 7301 – 8787
) -8.82 … V1280 Sco 2007.1 D(14) 3.78 $\pm$ 0.10 Fe II 1200 … DISC 3502 ( 3309
– 3772 ) -9.93 V1500 V1281 Sco 2007.1 S(26) 9.00 $\pm$ 0.30 Fe II 640 … BULGE
8210 ( 7511 – 8935 ) … … V1310 Sco 2010.2 J(113) 10.50 $\pm$ 0.30 Fe II 670 …
bulge 8027 ( 7292 – 8782 ) … … V1311 Sco 2010.4 S(8) 8.60 $\pm$ 0.30 He/N?
3600 … bulge? 8028 ( 7283 – 8768 ) -8.87 … V1312 Sco 2011.5 S(15) 9.50 $\pm$
0.50 Fe II 1800 … bulge? 8070 ( 7344 – 8827 ) … … V1313 Sco 2011.8 S(18) 10.40
$\pm$ 0.50 Fe II 3000 50 BULGE 8272 ( 7561 – 8982 ) … RG V1324 Sco 2012.5
D(30) 10.00 $\pm$ 0.10 Fe II 2000 … bulge 7866 ( 7149 – 8617 ) -8.07 $\gamma$,
PreERise V1533 Sco 2013.5 … $<$11.3 $\pm$ 0.20 … … … bulge 8106 ( 7368 – 8852
) … … V1534 Sco 2014.2 S(9) 11.55 $\pm$ 0.20 He/N 7000 520 BULGE 8231 ( 7531 –
8936 ) -6.47 RG V1535 Sco 2015.2 P(20) 9.50 $\pm$ 0.20 He/N 2000 50 BULGE 7790
( 7095 – 8540 ) -7.44 RG V1655 Sco 2016.5 D(50) 12.10 $\pm$ 0.10 Fe II 1400 …
bulge 8215 ( 7468 – 8938 ) -6.01 $\gamma$ V1656 Sco 2016.8 … 11.43 $\pm$ 0.30
Fe II 1800 … bulge 8073 ( 7335 – 8816 ) -8.07 … V1657 Sco 2017.2 … $<$12.7
$\pm$ 0.20 Fe II 2000 650 BULGE 8316 ( 7624 – 9047 ) … RG V1658 Sco 2015.2 …
$<$12.7 $\pm$ 0.20 Fe II 1810 … BULGE 8141 ( 7406 – 8879 ) … … V1659 Sco
2016.8 … $<$12.3 $\pm$ 0.20 Fe II … … bulge 8135 ( 7396 – 8883 ) … … V1660 Sco
2017.9 … $<$14.1 $\pm$ 0.20 He/N … … BULGE 8140 ( 7399 – 8885 ) … … V1661 Sco
2018.1 … $<$10.7 $\pm$ 0.20 Fe II 1950 … bulge 8152 ( 7395 – 8880 ) … … V1662
Sco 2018.2 … $<$10.5 $\pm$ 0.20 Fe II 1700 … DISC 5370 ( 3853 – 8175 ) … …
V1663 Sco 2018.2 … $<$11.7 $\pm$ 0.20 Fe II 1900 … bulge 8117 ( 7374 – 8861 )
… … V1706 Sco 2019.5 J(170) 12.20 $\pm$ 0.40 Fe II 820 … BULGE 8136 ( 7404 –
8878 ) -7.31 … V1707 Sco 2019.8 S(7) 11.80 $\pm$ 0.20 Fe II 6900 … bulge 8038
( 7297 – 8781 ) -8.62 … V1709 Sco 2020.3 D 13.60 $\pm$ 0.30 … 1300 … BULGE
8067 ( 7335 – 8816 ) -8.06 … V1710 Sco 2021.4 S(11) 8.60 $\pm$ 0.10 Fe II 2380
… disc? 5258 ( 3200 – 8228 ) … … V1711 Sco 2021.6 C(38) 11.09 $\pm$ 0.10 Fe II
1800 … bulge 8095 ( 7359 – 8838 ) -7.67 … Nova 1437 Sco 1437.2 … $<$3 $\pm$
0.20 … … … DISC 1030 ( 999 – 1073 ) … … EU Sct 1949.6 S(42) 8.40 $\pm$ 0.10 Fe
II … 68 DISC 7823 ( 6853 – 9771 ) -8.67 RG FS Sct 1952.5 J 9.43 $\pm$ 0.36 Fe
II … 5.7 DISC 5176 ( 4072 – 8034 ) … SubG FV Sct 1960.5 … $<$11.1 $\pm$ 0.45 …
… … disc 6351 ( 3699 – 9343 ) … … V366 Sct 1961.4 … $<$11.3 $\pm$ 3.01 … … …
DISC 8466 ( 6289 – 13423 ) … … V368 Sct 1970.6 P(30) 6.90 $\pm$ 0.50 Fe II … …
DISC 2452 ( 1950 – 4181 ) … … V373 Sct 1975.5 J(79) 6.10 $\pm$ 0.10 … …
0.81910 DISC 1458 ( 1229 – 2343 ) -5.43 SubG V443 Sct 1989.7 J(60) 8.50 $\pm$
0.10 Fe II 1400 … DISC 2802 ( 2193 – 4583 ) … … V444 Sct 1991.7 P(23) 10.80
$\pm$ 0.40 Fe II, Ne … … DISC 7381 ( 5600 – 10718 ) … … V463 Sct 2000.2 J(24)
10.30 $\pm$ 0.40 Fe II 990 … bulge 8076 ( 7334 – 8820 ) -6.72 … V476 Sct
2005.7 S(28) 11.09 $\pm$ 0.10 Fe II 1200 … DISC 7820 ( 6247 – 10794 ) -9.27 …
V477 Sct 2005.8 S(6) 9.80 $\pm$ 0.30 Fe II 2900 … DISC 6258 ( 4426 – 9152 ) …
… V496 Sct 2009.8 S(98) 7.20 $\pm$ 0.20 Fe II 1200 … DISC 4517 ( 3629 – 6664 )
-7.84 … V611 Sct 2016.8 … $<$13.4 $\pm$ 0.20 He/N … … DISC 8090 ( 5758 – 12416
) … … V612 Sct 2017.6 J(236) 8.50 $\pm$ 0.10 Hybrid, Ne 1180 … bulge 8063 (
7330 – 8811 ) -8.05 … V613 Sct 2018.6 S(66) 10.70 $\pm$ 0.10 Fe II 1800 …
BULGE 8091 ( 7354 – 8835 ) -7.87 … V659 Sct 2019.9 … 8.36 $\pm$ 0.10 Hybrid …
… DISC 5539 ( 3639 – 8589 ) … … X Ser 1903.2 S(730) 8.74 $\pm$ 0.23 … … 1.478
DISC 3089 ( 2722 – 3843 ) -4.48 SubG, DN

Table 12: continued

Distances and Properties of All 402 Known Galactic Novae  Nova Year
LC($t_{3}$) $V_{peak}$ Spec. FWHM $P$ Pop. $D$ (68% range) $M_{V}$ Propertiesa
CT Ser 1948.3 … $<$7.7 $\pm$ 0.23 He/N … 0.195 DISC 2551 ( 2330 – 2904 ) … …
DZ Ser 1960.6 … $<$13.1 $\pm$ 0.36 He/N … … BULGE 8142 ( 7396 – 8883 ) … … FH
Ser 1970.1 D(62) 4.50 $\pm$ 0.10 Fe II … … DISC 1024 ( 970 – 1103 ) -7.41
Shell LW Ser 1978.2 D(52) 8.30 $\pm$ 0.10 Fe II … … bulge 7661 ( 6933 – 8412 )
-7.33 … MU Ser 1983.1 … 7.70 $\pm$ 0.40 He/N 1230 … BULGE 7262 ( 6503 – 8025 )
-7.85 … V378 Ser 2005.2 J(93) 11.60 $\pm$ 0.40 Fe II 1100 … BULGE 8238 ( 7500
– 8969 ) -5.27 … V556 Ser 2014.0 … $<$12.3 $\pm$ 0.20 Fe II 1145 … BULGE 8166
( 7420 – 8903 ) … … V670 Ser 2020.2 S(6) 12.50 $\pm$ 0.40 Fe II 4200 … bulge?
8083 ( 7345 – 8826 ) -7.93 … XX Tau 1927.9 D(43) 5.59 $\pm$ 0.25 Fe II …
0.12936 DISC 2041 ( 1711 – 2904 ) -6.89 NonOrbP NR TrA 2008.2 J(61) 8.60 $\pm$
0.20 Fe II … 0.2192 DISC 4864 ( 4212 – 6254 ) -5.52 Ecl RW UMi 1956.7 … $<$5.9
$\pm$ 0.21 … … 0.05912 DISC 1993 ( 1721 – 2592 ) … $<$Gap, V1500 CN Vel 1905.9
S $<$9.9 $\pm$ 0.23 … … 0.2202 DISC 4227 ( 3654 – 6186 ) … … CQ Vel 1940.3
S(50) 8.30 $\pm$ 0.23 … … 0.11272 DISC 3061 ( 2372 – 5486 ) -5.96 … V382 Vel
1999.4 S(13) 2.80 $\pm$ 0.10 He/N, Ne 2400 0.1461 DISC 1531 ( 1454 – 1638 )
-8.50 … V549 Vel 2017.8 J(118) 9.10 $\pm$ 0.30 Fe II … 0.40317 DISC 2056 (
1753 – 5052 ) … $\gamma$ LU Vul 1968.8 S(21) 8.19 $\pm$ 0.45 He/N 820 … DISC
4998 ( 3952 – 8687 ) … … LV Vul 1968.3 S(38) 4.50 $\pm$ 0.10 Fe II … … DISC
2887 ( 2420 – 4234 ) -9.57 Shell NQ Vul 1976.8 D(50) 6.20 $\pm$ 0.10 Fe II …
0.14626 DISC 1210 ( 1128 – 1350 ) -7.07 Shell PW Vul 1984.6 J(116) 6.40 $\pm$
0.10 Fe II … 0.12858 DISC 2114 ( 1901 – 2603 ) -6.93 NonOrbP, Shell QU Vul
1985.0 P(36) 5.30 $\pm$ 0.10 Fe II, Ne … 0.11176 DISC 1742 ( 1432 – 2772 )
-7.61 Ecl, Shell QV Vul 1987.9 D(47) 7.10 $\pm$ 0.10 Fe II 920 … DISC 2808 (
2348 – 4011 ) -6.38 Shell V458 Vul 2007.6 J(20) 8.10 $\pm$ 0.20 Hybrid 1750
0.06812 DISC 5204 ( 4357 – 7750 ) -7.03 $<$Gap, InPNeb V459 Vul 2008.0 S(30)
7.60 $\pm$ 0.10 Fe II 910 … DISC 3971 ( 3226 – 5608 ) -8.06 … V569 Vul 2019.7
… $<$16.3 $\pm$ 0.20 … 1800 … DISC 7839 ( 5436 – 13726 ) … … V606 Vul 2021.6
D(96) 10.10 $\pm$ 0.10 Hybrid 1700 … DISC 4827 ( 3578 – 7811 ) … …

a Novae below and inside the nova Period Gap from 0.071–0.111 days are denoted
with $<$Gap and inGap. Novae with subgiant companion stars (roughly
0.6$<$$P$$<$10 days) and red giant companion stars (roughly $P$$>$10 days) are
marked as SubG and RG. Novae whose light curves display eclipses are denoted
with Ecl, display dwarf novae eruptions with DN, display inexplicable pre-
eruption rises with PreERise, display post-eruption dips with PostEDip,
display coherent and stable periods that are certainly not orbital or
rotational with NonOrbP, display very large amplitude irregular variability in
quiescence with LargeAmpVar, and display various types of inexplicable
rebrightenings are notated with Rebrighten. V1500 indicates the mysterious
V1500 Cyg stars where the post-eruption brightness many decades after the end
of the eruption remains at least 10$\times$ brighter than the pre-eruption
level. InPNeb; V458 Vul is the only nova to be at the centre of an observed
ordinary planetary nebula. Novae visible with $\gamma$-ray emission by the
Fermi spacecraft are marked $\gamma$. Novae for which I have measured the
steady period change between eruptions are marked with $\dot{P}$, while those
for which I have measured the change in the orbital period sharply across a
nova eruption are marked with $\Delta P$. V1500 Cyg is the only nova known to
be an asynchronous polar (AP). Novae inside host globular clusters are listed
with in M14 or in M80. Binaries that are either confidently or likely
Intermediate Polars (IP or IP?) are identified as in the catalogue of K. Mukai
(https://asd.gsfc.nasa.gov/Koji.Mukai/iphome/catalog/alpha.html). Startlingly,
V2487 Oph suffers the most-energetic and the most-frequent Superflares out of
the many classes of stars that display bright optical flares caused by stellar
magnetic reconnection.

The resultant probability distributions are often roughly symmetric and
similar to Gaussians in shape. But many novae have distributions that are
substantially asymmetric. The most extreme cases are for FM Sgr and V1175 Sgr,
their sharp peaks in the distribution (i.e., the mode) ares outside the middle
68 per cent of the distribution.

I have calculated the best-estimate $D$ values and the middle 68 per cent
probability ranges for all 402 novae. These are presented in Table 6. I have a
total of 220 novae with good accuracy in their distances. (For this, I take a
‘good’ distance to be one where half the quoted distance range is
$\leq$0.3$D$.) Out of these 219 novae with good distances, 52 are disc novae,
with the primary basis for the accuracy being their Gaia parallaxes. The set
of novae with good distances includes all 165 bulge novae. (These include only
20 novae with $\sigma_{\varpi}$$<$0.10 mas, so the distance accuracy is almost
entirely due to the identification as a bulge novae, with this being confident
and reliable in all but a few marginal cases.) In addition the two novae in
globular clusters have accurate Gaia parallaxes to the cluster. In the end, as
the primary goal of my program, I have 220 novae (out of the 402 known
galactic novae) that have accurate distances.

Table 6 also lists many of the fundamental measured properties for all 402
galactic novae. The first column gives the nova names, in the required GCVS
order. The second column gives the year of the peak, or gives “RN” for
recurrent novae. The third column gives the light curve classification
according to the divisions of Strope et al. (2010), consisting of one or two
letters (S, P, PP, O, C, D, J, and F) plus the $t_{3}$ time (the number of
days from the nova peak until the last time it fades below 3.0 mag under the
peak) in parentheses. All of these classifications are from my own work with
the original light curves for this paper. The fourth column gives the peak
V-band magnitude, $V_{peak}$ and its one-sigma uncertainty. These magnitudes
are taken from my analysis of the original light curves, with the B-magnitudes
converted to V-magnitudes, and care taken to identify when the peak was
reliably detected. The fifth column gives the spectral class, with the main
classes being Fe II, He/N, and hybrid, while neon-novae are indicated with an
“Ne”. The next column gives the FWHM of the H$\alpha$ line in units of km/s,
fairly early in the eruption. These data are often heterogeneous, with the
only line width information coming from other hydrogen lines, or only the FWZI
is quoted, or late in the eruption. The next column lists the 156 known
orbital periods, $P$ in days, as collected in Schaefer (2022), with this
including my 49 new orbital periods. The eighth column gives my assignments
for the nova population, as taken from Section 4. The ninth column gives my
derived distances, $D$ in parsecs, along with the range of the central 68 per
cent of the probability distribution, with this column being the primary
product of this paper. The tenth column gives the absolute magnitude at peak
in the V-band, $M_{V,peak}$. These values are all calculated from the
tabulated $V_{peak}$, $E(B-V)$, and $D$, with full extinction correction. The
print copy of this table only shows the $M_{V,peak}$ values for those with
uncertainties better than 1.0 mag. The on-line Supplementary Material has this
column containing the measured values for all the novae, plus their formal
one-sigma error bars. The last column gives a listing of the various unusual
properties for each nova, with the notations keyed in a footnote to the table.

I have added a number of additional columns of measured properties, with these
appearing only in the on-line Supplementary Material. Three of the columns
give the galactic coordinates $\ell$, b, and $\Theta_{GC}$, all in units of
degrees. The next column gives my final values for $E(B-V)$ and its one sigma
error bars, in units of magnitudes, for all 402 novae. Many of these are taken
from Özdönmez et al. (2018), or from subsequent literature, or from my own
light curve analyses, or from prudent estimates based on the upper limits from
Schlafly & Finkbeiner (2011). The next column gives the $t_{2}$ value, which
is the number of days over which the nova light curve declines from its
highest peak until the last time the nova fades by more than 2.0 mags from the
peak. The last extra column gives the Gaia DR3 parallax and its one sigma
uncertainty, as in Table 5.

Table 6 is intended to be an exhaustive summary of all the known properties of
all 402 known galactic novae. The one line of information gives a
comprehensive summary of all its known properties, and each line reveals the
‘personality’ of each nova. This full table can be used for looking up
properties of individual novae, for standardizing the prior results from the
long history of measuring novae, and for demographic studies of a wide variety
of nova properties.

##  7 APPLICATIONS

###  7.1 Nova Disc Scale Height

Duerbeck (1984) collects nine measures of the exponential scale height for
novae, with values ranging from 72–440 pc, and then went on to use 20 novae to
derive his own scale height of 125 pc. The height of each nova above the
central plane of our galaxy, $Z$, is $D$$\sin$($\it b$). My histograms of the
distances from the galactic plane, $|Z|$, shows that all sets of disc novae
have a sharp drop in numbers from $|Z|$=0, and the distributions are close to
exponential. The distribution can be accurately represented by the exponential
scale height, which is the same as the average, $\langle|Z|\rangle$.

The derived $\langle|Z|\rangle$ will vary with the selection of disc novae
included in the average. If the set for averaging includes novae with large
uncertainty in $D$, then $\langle|Z|\rangle$ will systematically grow in size
to be comparable to the error bars. So the set of novae for averaging should
be restricted to only the best-measured novae with uncertainties substantially
smaller than 150 pc or so. But if we make the set too small, then the scale
height will be uncertain due to small-number statistics. Further, some sort of
volume-limited sample is needed to minimize selection effects. To avoid edge
effects in this volume, we need to use an infinite cylinder, centred on the
Sun, perpendicular to the galactic plane. Further, I have not used any novae
with $\theta_{GC}$$<$20$\degr$, so as to avoid any possible confusion with
bulge novae.

I have adopted a middle set, with a cylinder radius of 2000 pc and requiring
that the uncertainty in $Z$ be less than 30 pc. This results in a set of 34
disc novae with good distances. This set has $\langle|Z|\rangle$=140 pc. The
uncertainty is defined by the reasonable variations for inclusion in the
averaging set, with this being $\pm$10 pc. So I conclude that the novae are
distributed exponentially above and below the galactic plane, with an
exponential scale height of 140$\pm$10 pc. This $\langle|Z|\rangle$=140 pc
value is used in equation (6) to calculate the final nova distances, as in
Section 6 and Table 6.

###  7.2 Absolute Magnitude At Peak Light In The V-band

Figure 4: Absolute magnitude at peak ($M_{V,peak}$) versus decline rate
($t_{3}$). This plot shows the MMRD for 192 novae with measured $t_{3}$ and
the uncertainty in $M_{V,peak}$ of less than 1.0 mag. We see a significant
correlation, $M_{V,peak}=-7.6+1.5\log(t_{3}/30)$, as marked by the slanted
line. But we also see a huge scatter, such that the ‘correlation’ just looks
like a round blob. The only reason that the correlation is significant is
because I have 192 novae. All the prior samples testing the MMRD have had much
fewer novae, and thus the many samples have not shown any significant MMRD
relation, while one prior sample has randomly happened to show a poor MMRD.
The MMRD shown here supersedes all prior galactic results. The conclusion is
that the MMRD does really exist, but the huge scatter dominates over the
effect and thus the relation is not useable for any purpose that I can think
of.

What is the average $M_{V,peak}$? Schaefer (2018) used Gaia DR2 data for novae
with accurate parallaxes to yield an average of $-$7.0 with an RMS scatter of
1.4 mag. Now, with the 213 novae in Table 6, the average is $-$7.45 mag with
an RMS scatter of 1.33 mag. Various subsets give similar values, with a
variation over 0.2 mag or so, for example, the 15 novae with error bars
$<$0.30 mag have an average of $-$7.51 mag with an RMS scatter of 1.35 mag.
For the full set of 213 novae, the top end of the luminosity distribution has
8 novae evenly spread over the range $-$10.0$>$$M_{V,peak}$$>$$-$11.13. These
include the famous V1500 Cyg at $-$10.38, and the extreme case is the bulge
nova V3661 Oph at $-$11.13. At the low-luminosity end, 6 novae span
$-$3.62$>$$M_{V,peak}$$>$$-$5.0. The extreme case is V972 Oph at $-$3.62 mag.
Three of the six cases have flat-topped F-class light curves (DO Aql, V1310
Sgr, and BT Mon), pointing to this class being systematically low-energy
eruptions. For all of these extreme cases, I see no indications that the
$M_{V,peak}$ values have any large measurement or systematic errors past what
is expressed in the stated error bars. So it appears that the range of the
nova phenomenon extends from at least $-$5.0 to $-$10.0.

These D and $M_{V,peak}$ values were derived with an assumed prior for peaks
of -7.0$\pm$1.4 mag. Should this be updated to the new average of
$-$7.45$\pm$1.33 mag? Or should we change the $P_{peak}$ priors to represent
the various correlations with light curve and spectral classes (see below)?
The answer is clearly ‘no’, for two strong reasons. First, the Bayesian method
requires the use of prior information, so it is incorrect to feed the
calculated results back into the calculation. Second, doing so would make for
little difference anyway. That is, the adopted error bar of $\pm$1.4 mag is
already so weak that any change to the adopted $M_{V,peak}$ will lead to
changes in $D$ that are greatly smaller than the quoted error bars.

Now with 213 good measures, I can search for correlations between $M_{V,peak}$
and any of many other properties listed in Table 6. Most properties have no
significant correlation with the peak luminosity, including the various
spectral classes (e.g., Fe II, He/N, and Neon), the shell expansion velocity
(as measured by the FWHM of the Balmer lines), the status as a RN, and the
galactic population (disc or bulge). I find only two properties with
significant correlations.

The first correlation is with the light curve classification. The S-class,
P-class, O-class, and C-class novae are for the high-energy novae (i.e., with
large FWHM, He/N spectral class, high white dwarf masses, and fast declines),
and these are grouped together here. The D-, J-, and F-classes are for low-
energy novae, and are grouped together here. With 124 SPOC novae, the average
is $-$7.75$\pm$0.12. With 75 DJF novae, the average is $-$6.95$\pm$0.15. So
just by looking at the shape of the light curve, we can identify whether the
nova peaks at relatively high-or-low luminosity.

The second correlation is that $M_{V,peak}$ is a function of the decline rate
of the light curve (expressed as $t_{3}$ or $t_{2}$). Specifically, the 92
fast novae (say, with $t_{3}$$<$30 days) have $\langle M_{V,peak}\rangle$
equal to $-$8.13$\pm$0.13, while the 20 slow novae (with $t_{3}$$>$100 days)
have $-$6.80$\pm$0.25. That is a 1.33 mag difference, which is a factor of
3.4$\times$ in peak luminosity. Fig. 4 shows a plot of $M_{V,peak}$ versus
$t_{3}$, and we see a significant trend, despite the huge scatter making the
data points looking like a round blob. The same trend with the same large
scatter is seen when only using novae with the uncertainty in $M_{V,peak}$
that is $<$0.5 mag. This trend is identical for SPOC versus JDF light curve
classes, and identical for bulge versus disc novae. A least square fit gives
the relation $M_{V,peak}=-7.6+1.5\log(t_{3}/30)$, for $t_{3}$ in units of
days. The existence of this correlation is significant at the 8.6-sigma level.
But the scatter about this relation is huge, so the correlation is significant
only because I am using 192 novae. The scatter has an RMS of 1.0 mag on top of
the measurement errors. The relevant figure is that the disagreement from
model to observation has the 68 per cent range of 2.4 mag and the total range
of 6.2 mag. That is, the 1-sigma uncertainty in using this relation results in
a range of luminosity by a factor of 10$\times$. With the very large scatter
around the relation, there is little utility for physical models of any
specific system. With this large scatter, the use of this relation is a
negligible improvement over using a simple average of $-$7.0$\pm$1.4 mag.

This relation fits into a long history of the so-called ‘Maximum Magnitude
versus Rate of Decline’ (MMRD). The MMRD was first put forth for novae in the
Andromeda Galaxy (Hubble 1929), with follow-ups, extensions, and refinements
by many workers from the 1950s until recently, with the first theoretical
explanation by Shara (1981). MMRD relations have been presented with many
formulations, involving magnitudes at various times in the eruption, involving
B- and V-magnitudes, involving decline rates over 2 and 3 magnitudes, and
involving logarithms, broken logs, and arc-tangents. The best expression of
the MMRD was in Downes & Duerbeck (2000), with no improvements since then.
Historically, the MMRD has been heavily used, largely because it was the only
way to estimate distances to most novae. The MMRD has always been know to be
poor, due to the huge scatter in the relation. Starting with Kasliwal et al.
(2011), the relation fell into disrepute when the novae in the galaxies M31,
M81, M82, NGC 2403, and NGC 891 did not display anything like the MMRD. They
also showed that the RNe do not obey the MMRD, nor do the latest theory models
of Yaron et al. (2005). Then Shara et al. (2017b) showed that the novae in M87
do not follow the MMRD. Then Schaefer (2018) used Gaia DR2 parallaxes to show
that 26 galactic novae in the ‘Gold’ sample followed a shifted MMRD with huge
scatter, while the 13 and 23 galactic novae in the ‘Silver’ and ‘Bronze’
samples do not show anything like any MMRD. The Gold sample is largely the
same as the Downes & Duerbeck sample, so we only really have just one sample
of novae that poorly follows the MMRD. In stark opposition, we have the MMRD
being denied for two other galactic samples, the RNe, theory models, and by
novae in six external galaxies.

Now, with 192 novae and the best distances, my confirmation of the MMRD
supersedes all the prior results for our Milky Way. Presumably the old samples
either showed or denied the poor MMRD due to the randomness of small samples
out of a highly scattered distribution. That is, the Downes & Duerbeck sample
displayed a poor MMRD by the random happenstance of the novae going into their
sample, while other samples had the happenstance to have the scatter being too
large to allow the MMRD to be visible. The point is that the MMRD is now seen
to be real, even though the scatter is so large as to debilitate the use of
this relation. We are now left with the question as to why the Milky Way has a
poor MMRD, while the six external galaxies do not show it at all. I think that
the reconciliation is that the searches in each external galaxy produces a
relatively small number of novae, and the small numbers with huge scatter will
always make for no significant detection of the MMRD. That is, the huge
scatter means that the MMRD can only be confidently detected when a large
number of novae are included (like 192 galactic novae in this paper), whereas
no MMRD can be significant when relatively small numbers of novae are
included.

In the end, we are left with $\langle M_{V,peak}\rangle$=$-$7.45$\pm$1.33 mag
being nearly as good a description of the data as
$M_{V,peak}=-7.6+1.5\log(t_{3}/30)$. The MMRD is definitely a real effect for
galactic novae, and likely for external galaxies , despite the large scatter.
The theory explanation is as given by Shara (1981), with both $M_{V,peak}$ and
$t_{3}$ directly tied to the white dwarf mass. Despite now having a
significant existence, the MMRD has so much scatter that it is useless for
evaluating the distance to any particular novae.

###  7.3 Bulge Versus Disc Novae

Table 13: Comparing Bulge and Disc Populations Property | Bulge Novae | Disc Novae
---|---|---
$\langle M_{V}\rangle$ (mag) |  $-$7.73 (26, $\pm$1.28) |  $-$7.51 (45, $\pm$1.32)
Median FWHM (km/s) | 1500 (93, $\pm$1700) | 1670 (116, $\pm$1220)
Median $t_{3}$ (days) | 28 (79, $\pm$67) | 38 (163, $\pm$110)
SPOC fraction | 0.62 (51 / 82) | 0.61 (105 / 173)
Fe II fraction | 0.80 (77 / 96) | 0.72 (106 / 147)
He/N fraction | 0.14 (13 / 96) | 0.18 (27 / 147)
Hybrid fraction | 0.06 (6 / 96) | 0.09 (13 /147)
Neon fraction | 0.08 (8 / 100) | 0.19 (29 / 151)
Helium fraction | 0.00 (0 / 100) | 0.01 (1 / 151)
Subgiant fraction | 0.22 (8 / 37) | 0.18 (21 / 115)
Red giant fraction | 0.35 (13 / 37) | 0.05 (6 / 115)

Now, I have a confident list of all known bulge novae and disc novae, plus an
exhaustive list of their primary known properties. So I can systematically
make a comprehensive study of the two populations.

For this, I have used the 161 novae identified as ‘BULGE’ or ‘bulge’ and the
224 novae identified as ‘DISC’. The results are in Table 7. Each line presents
a property for which either a fraction or an average can be derived. The
parenthetical numbers are either the numbers of novae in the fraction, or the
number of novae in the average along with the overall RMS of the population.
The population differences in $\langle M_{V}\rangle$, the median FWHM of the
velocity width of the Balmer lines, and the median $t_{3}$ decline speed are
all within one-sigma. Similarly, the fraction of novae that are SPOC (i.e.,
with light curve classes S, P, O, or C), as well as the fractions for the
various spectral classes, are indistinguishable between bulge and disc novae.
Further, the fraction of novae with subgiant companion stars (i.e., those with
0.6$<$$P$$<$10 days) is the same between the populations.

I can find only one property for which the bulge and disc novae differ, and
that is the red giant fraction. The nova systems with red giant companions are
easily recognized, even out past $D_{GC}$, by their infrared flux whose
spectral energy distribution is a warm blackbody, shining above the usual blue
accretion disc flux (Schaefer 2022). Their orbital periods are from 10 days
out to near 2440 days. The bulge novae have a red giant fraction of 35$\pm$8
per cent, while the disc novae have a red giant fraction of 5$\pm$2 per cent.
This is a highly significant difference. A similar result was found by
Schaefer (2022).

So the only difference between the bulge and disc populations is that the
bulge has a high red giant fraction. The first-glance explanation is that the
bulge novae are older, on average, than disc novae, so the nascent wide
binaries formed with a white dwarf will have longer time for the companion to
evolve to its red giant stage and come into contact. But my simplistic
modeling suggests that this explanation cannot be fine tuned to get such a
large difference. Further, such an explanation has a hard time allowing for
the subgiant fractions to be equal between the two populations. Another
mystery arises because the novae with red giant companions in the Andromeda
Galaxy are consistent with being entirely in the disc population (Williams et
al. 2016). I am not aware of any selection effect or systematic problem that
can account for the large differences in the red giant fractions. So I am left
with no useable explanation for the Milky Way novae having the systems with
red giants concentrated in the bulge population.

The bulge novae are neither faster or slower, neither brighter or dimmer than
disc novae, nor are the bulge novae different in light curve or spectral
class. Other than the red giant fraction, the bulge novae are
indistinguishable from the disc novae.

###  7.4 RS Oph Is Powered By Roche Lobe Overflow

The issue of the distance to RS Oph determines the nature of the accretion in
the binary (Schaefer 2009; Wynn 2008). For distances $<$2000 pc, the companion
must be substantially smaller than its Roche lobe, so the accretion can only
come by the white dwarf capturing some fraction of the red giant’s stellar
wind. For distances over $\gtrsim$2700 pc, the companion must be so large as
to fill its Roche lobe, and the accretion would be entirely by Roche lobe
overflow.

Historically, the first widely seen distance estimates were those of Hjellming
et al. (1986) and Cassatella et al. (1985), with extinction distances of 1600
pc. Most later papers explicitly cited these papers, and 1600 pc became the
default by repetition. Then modelers took results assumed from this distance
(the system having wind accretion) to calculate models, and then derived
distances comparable to 1600 pc, a circular conclusion. In an uncritical
review of RS Oph distances up until 2006, Barry et al. (2008) merely collected
the many published distance measures and took the median, to get 1400 pc. The
legacy of this band-wagon-effect (Schaefer 2008) has continued to the current
time, with the most recent RS Oph publication (Cheung et al. 2022) adopting
1600 pc as explicitly attributed to the Hjellming paper.

The problems for this vote-on-the-distance result are that the distances
reported by both Hjellming555The mistake in Hjellming et al. (1986) was to
adopt a linear calibration for their measure of extinction, with this only
being reasonable for a line of site that keeps exactly in the galactic plane.
RS Oph has a galactic latitude of $\it b$=$+$10.37$\degr$, so the line of
sight to RS Oph will be 300 pc out of the plane for a distance of 1600 pc and
far outside almost all of the galaxy’s extinction. That is, Hjellming’s
calibration relation is greatly wrong, and the distance estimate is greatly