# Multiband Simultaneous Photometry of Type II SN 2023ixf with _Mephisto_ and
the Twin 50-cm Telescopes

Yuan-Pei Yang South-Western Institute for Astronomy Research, Yunnan
University, Kunming, Yunnan 650504, P.R. China  These authors contributed
equally to this work  Xiangkun Liu South-Western Institute for Astronomy
Research, Yunnan University, Kunming, Yunnan 650504, P.R. China  These authors
contributed equally to this work  Yu Pan South-Western Institute for Astronomy
Research, Yunnan University, Kunming, Yunnan 650504, P.R. China  Xinzhong Er
South-Western Institute for Astronomy Research, Yunnan University, Kunming,
Yunnan 650504, P.R. China  Dezi Liu South-Western Institute for Astronomy
Research, Yunnan University, Kunming, Yunnan 650504, P.R. China  Yuan Fang
South-Western Institute for Astronomy Research, Yunnan University, Kunming,
Yunnan 650504, P.R. China  Guowang Du South-Western Institute for Astronomy
Research, Yunnan University, Kunming, Yunnan 650504, P.R. China  Yongzhi Cai
Yunnan Observatories, Chinese Academy of Sciences, Kunming 650216, P.R. China
Key Laboratory for the Structure and Evolution of Celestial Objects, Chinese
Academy of Sciences, Kunming 650216, P.R. China  International Centre of
Supernovae, Yunnan Key Laboratory, Kunming 650216, P.R. China  Xian Xu South-
Western Institute for Astronomy Research, Yunnan University, Kunming, Yunnan
650504, P.R. China  Xinlei Chen South-Western Institute for Astronomy
Research, Yunnan University, Kunming, Yunnan 650504, P.R. China  Xingzhu Zou
South-Western Institute for Astronomy Research, Yunnan University, Kunming,
Yunnan 650504, P.R. China  Helong Guo South-Western Institute for Astronomy
Research, Yunnan University, Kunming, Yunnan 650504, P.R. China  Chenxu Liu
South-Western Institute for Astronomy Research, Yunnan University, Kunming,
Yunnan 650504, P.R. China  Yehao Cheng South-Western Institute for Astronomy
Research, Yunnan University, Kunming, Yunnan 650504, P.R. China  Brajesh Kumar
South-Western Institute for Astronomy Research, Yunnan University, Kunming,
Yunnan 650504, P.R. China  Xiaowei Liu South-Western Institute for Astronomy
Research, Yunnan University, Kunming, Yunnan 650504, P.R. China

###### Abstract

SN 2023ixf, recently reported in the nearby galaxy M101 at a distance of
$6.85~{}{\rm Mpc}$, was one of the closest and brightest core-collapse
supernovae (CCSNe) in the last decade. In this work, we present multi-
wavelength photometric observation of SN 2023ixf with the Multi-channel
Photometric Survey Telescope (Mephisto) in $uvgr$ bands and with the twin
50-cm telescopes in $griz$ bands. We find that the bolometric luminosity
reached the maximum value of $3\times 10^{43}~{}{\rm erg~{}s^{-1}}$ at 3.9
days after the explosion and fully settled onto the radioactive tail at $\sim
90$ days. The effective temperature decreased from $3.2\times 10^{4}~{}{\rm
K}$ at the first observation and approached to a constant of
$\sim(3000-4000)~{}{\rm K}$ after the first two months. The evolution of the
photospheric radius is consistent with a homologous expansion with a velocity
of $8700~{}{\rm km~{}s^{-1}}$ in the first two months, and it shrunk
subsequently. Based on the radioactive tail, the initial nickel mass is about
$M_{\rm Ni}\sim 0.098M_{\odot}$. The explosion energy and the ejecta mass are
estimated to be $E\simeq(1.0-5.7)\times 10^{51}~{}{\rm erg}$ and $M_{\rm
ej}\simeq(3.8-16)M_{\odot}$, respectively. The peak bolometric luminosity is
proposed to be contributed by the interaction between the ejecta and the
circumstellar medium (CSM). We find a shocked CSM mass of $M_{\rm CSM}\sim
0.013M_{\odot}$, a CSM density of $\rho_{\rm CSM}\sim 2.5\times
10^{-13}~{}{\rm g~{}cm^{-3}}$ and a mass loss rate of the progenitor of
$\dot{M}\sim 0.022M_{\odot}~{}{\rm yr^{-1}}$.

Core-collapse supernovae (304); Type II supernovae (1731); Circumstellar
matter (241); Stellar mass loss (1613)

##  1 Introduction

Core-collapse supernovae (CCSNe) arise from the core collapses of massive
stars ($M\gtrsim 8M_{\odot}$) in their final evolutionary stages when the
radiation pressure from the nuclear fusion in the core cannot resist its own
gravity. Given the extreme physical conditions, many details of the explosion
process remain elusive. Based on the observed spectra and light curves, CCSNe
could be classified into types IIP, IIL, IIn, IIb, Ib, and Ic (Filippenko,
1997; Modjaz et al., 2019). CCSNe retaining a large portion of the hydrogen
envelope are known as Type II SNe, and their observed spectra are dominated by
the Balmer lines. CCSNe having no hydrogen envelope but showing helium
features are known as Type Ib. Those that have lost much or all of their
helium envelope are known as Type Ic.

SNe II are among the most commonly observed SNe. They mark the deaths of
massive stars and play an important role in the cosmic chemical enrichment.
The light curves and spectra of SNe II give insight into the SN explosion
mechanisms and the progenitor properties. The observed features of the light
curves and the spectra of the SNe II vary across the sub-classes that depend
on the fraction of the losses of the outer layer(s) (e.g., Branch & Wheeler,
2017). SNe IIP have thick hydrogen envelopes and show long plateau phases
($\sim 100$ days) with roughly constant or slowly declining luminosity
(Anderson et al., 2014), and about half of CCSNe are SNe IIP. SNe IIL have
thinner envelopes and decline more quickly and account for 6% of all CCSNe.
The differentiation between SNe IIP and SNe IIL is mainly based on photometry,
although it is not clear that the light curves of SNe IIL can be rigorously
distinguished from those of SNe IIP (Anderson et al., 2014; Sanders et al.,
2015; Holoien et al., 2016). SNe IIn, accounting for 10% of all CCSNe, are
characterized by narrow ($\sim 10-100~{}{\rm km~{}s^{-1}}$) or intermediate-
width ($\sim 1000~{}{\rm km~{}s^{-1}}$ ) hydrogen emission lines attributed to
the circumstellar interaction (Schlegel, 1990). It is noteworthy that some SNe
IIL also show narrow emission lines. Meanwhile, some SNe IIn present linear-
decline phases in their light curves (Di Carlo et al., 2002; Smith et al.,
2009). It is unclear whether SNe IIL can be rigorously distinguished from SNe
IIn. Therefore, it is crucial to investigate the observational properties of
Type II SNe in detail.

Very recently, SN 2023ixf was reported on 2023 May 19.727 UTC in the nearby
face-on “Pinwheel Galaxy” Messier 101 (M101; NGC 5457) (Itagaki, 2023) at a
distance of $6.85\pm 0.15~{}{\rm Mpc}$ (Riess et al., 2022), and it was one of
the closest and brightest CCSNe in the last decade. The evolution of SN
2023ixf has been extensively monitored by numerous facilities all over the
world, and both professional and amateur astronomers reported their early
observations of photometry (e.g., Balam & Kendurkar, 2023; Brothers et al.,
2023; Chen et al., 2023; D’Avanzo et al., 2023; Daglas, 2023; Desrosiers et
al., 2023; Fowler et al., 2023; González-Carballo et al., 2023; Kendurkar &
Balam, 2023b, c, d; Koltenbah, 2023; Li et al., 2023; Maund et al., 2023;
Mayya et al., 2023; Pessev et al., 2023; Sgro et al., 2023; Silva, 2023a, b;
Singh et al., 2023; Vannini, 2023; Vannini & Julio, 2023a, b; Villafane et
al., 2023; Zimmerman et al., 2024) and spectroscopy (e.g., BenZvi et al.,
2023a, b; Lundquist et al., 2023; Stritzinger et al., 2023; Sutaria & Ray,
2023; Sutaria et al., 2023; Zhang et al., 2023; Zimmerman et al., 2024) of
this object. SN 2023ixf was classified as a Type II SN (Perley et al., 2023)
and showed a strong blue continuum and prominent optical flash-ionization
features (H, He, N, and C) in its early-phase spectrum, all indicative of the
presence of circumstellar medium (CSM). Interestingly, the early photometric
and spectroscopic studies have revealed evidence of the interaction between
the SN ejecta and a dense confined CSM that boosted the early-phase optical
luminosity of the SN (Bostroem et al., 2023; Hiramatsu et al., 2023;
Hosseinzadeh et al., 2023; Jacobson-Galan et al., 2023; Smith et al., 2023;
Teja et al., 2023; Yamanaka et al., 2023; Li et al., 2023). The X-ray
detection, starting about four days after the explosion, also supported the
scenario of the circumstellar interaction (Chandra et al., 2023; Grefenstette
et al., 2023; Mereminskiy et al., 2023). So far no evidence has been found for
statistically significant emission in the sub-millimeter (Berger et al.,
2023), radio (at 10 GHz Matthews et al., 2023c, d, a, b), gamma-rays (Müller
et al., 2023) and neutrinos (Thwaites et al., 2023; Guetta et al., 2023).
Further, the spectropolarimetric investigation of this event revealed an
aspherical SN explosion and distinct geometry of the CSM (Vasylyev et al.,
2023) and provided a temporally-resolved description of a massive-star
explosion (Zimmerman et al., 2024).

In addition to the SN 2023ixf itself, the currently available photometric
information pointed to a luminous red supergiant with a dense shell of
circumstellar material as its progenitor candidate (Jencson et al., 2023;
Kilpatrick et al., 2023; Xiang et al., 2023; Liu et al., 2023). The progenitor
has been estimated to have a bolometric luminosity of
$L\sim(10^{4.7}-10^{5.4})L_{\odot}$, an effective temperature of $T_{\rm
eff}\sim(3200-3900)~{}{\rm K}$, and a mass of $M\sim(9-20)M_{\odot}$ (Niu et
al., 2023; Hosseinzadeh et al., 2023; Pledger & Shara, 2023; Jencson et al.,
2023; Kilpatrick et al., 2023; Soraisam et al., 2023; Neustadt et al., 2023;
Xiang et al., 2023). The estimated values of the parameters depend on the
model of the progenitor and its dust-driven wind environment reported in the
literature, though Van Dyk et al. (2023) recently proposed that the progenitor
candidate has a spectral energy distribution (SED) and luminosity strikingly
similar to a Galactic red supergiant analog (IRC-10414).

In this work, we present and model multi-wavelength photometry of SN 2023ixf
based on the observations with the Multi-channel Photometric Survey Telescope
(Mephisto) and with the twin 50-cm telescopes. We choose 2023 May 18 18:00
(MJD 60082.75) as phase zero, which is approximately midway between the first
detection of the SN and the deep nondetection, as proposed by Hosseinzadeh et
al. (2023). All times in the results and figures are related to this phase
zero. The paper is organized as follows. We describe our photometric
observations and present the observed properties of SN 2023ixf in Section 2.
We describe the evolution of the bolometric luminosity, effective temperature,
and photospheric radius in Section 3. We analyze the physical properties of SN
2023ixf in Section 4. The results are discussed and summarized in Section 5.
The convention $Q_{x}=Q/10^{x}$ is adopted in cgs units unless otherwise
specified.

##  2 Multiband Photometric Observations and Data Reduction

Since the discovery alert of SN 2023ixf, we carried out continuous photometric
follow-up observations from May 20, 2023 with the Multi-channel Photometric
Survey Telescope (Mephisto) under commissioning. The data presented in this
work were collected between May 20, 2023 and February 24, 2024. Mephisto is a
wide-field multi-channel telescope, the first of its type in the world,
located at Lijiang Observatory (IAU code: 044) of Yunnan Astronomical
Observatories, Chinese Academy of Sciences (CAS), with longitude
$100^{\circ}01^{\prime}48^{\prime\prime}$ East, latitude
$26^{\circ}41^{\prime}42^{\prime\prime}$ North and altitude $3200$m. The
telescope has a $1.6$m primary mirror and covers a field-of-view (FOV) of
$2^{\circ}$ in diameter. It is capable of imaging the same FOV in three
optical bands simultaneously and delivering real-time, high-quality colors of
unprecedented accuracy of surveyed celestial objects. Mephisto was equipped
with two commercial Oxford Instruments/Andor Technology iKon-XXL single-chip
CCD cameras for the blue and yellow channels during most of this period,
allowing imaging respectively $uv$ and $gr$ filters. Each camera employs an
e2v CCD231-C6 $6144\times 6160$ sensor with a pixel size of $15~{}\mu$m
(corresponding to $0.429$ arcsec projected on the sky), and covers an area
about a quarter of the full FOV. The wavelength coverages of the $uvgr$
filters are respectively $320-365$, $365-405$, $480-580$, and $580-680$ nm,
with a corresponding average efficiency of $90\%$, $93\%$, $99\%$, and $98\%$,
as shown in Figure 1. The observations were performed with filter combinations
of $ug$ and $vr$ for the blue and yellow channels in a simultaneous mode. To
ensure optimal signal-to-noise ratios of the target, the exposure times in
different bands were adjusted accordingly over the time, ranging from 10 to
300s, and 2 to 180s, for the $uv$ and $gr$ bands, respectively. After
eliminating data of bad quality, we are left with 242, 229, 327, and 317
exposures collected in 41 days in the $u$, $v$, $g$, and $r$ bands,
respectively.

Figure 1: The transmission curves of the filters of Mephisto and the twin
50-cm telescopes compared with other optical telescopes and filter systems.
The transmission curves of SkyMapper are given by Bessell et al. (2011), and
the transmission curves of SDSS and the filter systems of Johnson-Cousins and
Bessell are from http://svo2.cab.inta-csic.es/theory/fps/.

As auxiliary photometric telescopes of Mephisto, the twin 50-cm telescopes,
also located at Lijiang Observatory, were also involved in the observations of
SN 2023ixf. The twin telescopes are of model Alluna RC20, with a flat-field
corrector, and have a $505$mm optical aperture and a $f/8.1$ focal ratio. Each
telescope is equatorial mounted with a 10 Micron GM4000 mount, and equipped
with a FLI ML 50100 CCD camera. The camera employs an On Semi KAF-50100
sensor, with $8176\times 6132$ pixels of size $6\mu$m (corresponding to $0.3$
arcsec projected on the sky). The observations were performed simultaneously
with the twin telescopes, in two bands of filters $griz$. The CCDs were binned
by 2 at the readout, resulting in a pixel scale of $0.6$ arcsec. The $gr$
filters have transmission curves similar to those of Mephisto, and the
wavelength coverages of $iz$ filters are $775-900$ and $900-1050$ nm,
respectively, with an average efficiency of $99\%$. In most cases, the
exposure times were 10, 10, 60, and 120s in $griz$ bands, respectively. In
total, 34, 47, 50, and 30 exposures were collected in 12 days in $g$, $r$,
$i$, and $z$ bands, respectively, after excluding abnormal or overexposed
images.

Figure 2: Images of SN 2023ixf with Mephisto (a-f,i-l) in $uvgr$ bands and the
twin 50-cm telescopes (g,h,m,n) in $iz$ bands. Panel (a): the $vgr$-band
composite image of the “Pinwheel Galaxy” Messier 101 with Mephisto on 2023 May
20. Panel (b): the image of the region near SN 2023ixf. Panel (c-h): images of
SN 2023ixf in $uvgriz$ bands with different exposures on 2023 May 21. Panel
(i-n): images of SN 2023ixf in $uvgriz$ bands with different exposures on 2023
June 4.

We first performed pre-processing for each raw image, including bias/dark
subtraction, flat-fielding with twilight flats, and gain correction. After
pre-processing, the satellite trajectories and cosmic rays were removed. We
then carried out astrometric calibration, using stars from the Gaia EDR3
catalog as the reference (Gaia Collaboration et al., 2021). The astrometric
calibration is typically accurate to 40 mas. Multiple observations of HST
standard stars covering a sufficiently large airmass range were conducted on
two photometric nights, April 9 and May 29, 2023. Those observations were used
to derive the zero points of magnitude and first-order atmospheric extinction
coefficients of the observed bands for absolute photometric calibration for
data obtained with the Mephisto and the twin 50-cm telescopes. On this basis,
we further performed relative photometric calibration to account for non-
photometric observing conditions: 1) We first chose an image obtained in a
photometric night with small airmass and good image quality with FWHM $<2$
arcsec as the reference image for flux alignment; 2) We scaled the flux levels
of the remaining images to that of the reference image using stars of signal-
to-noise ratios S/N $>50$. We then applied the following procedures to
construct the multiband light curves of SN 2023ixf:

(1) Reference and target images: High-quality images obtained before the
supernova explosion were used as the reference images for image subtraction,
while images exposed after the explosion were target images.

(2) Image alignment: For each target image, we used SWARP (Bertin et al.,
2002) to subtract the sky background and align it with the reference image for
image subtraction for a selected area centered on SN 2023ixf. The selected
areas were $3000\times 3000$, and $1500\times 1500$ pixels, for images
obtained with Mephisto and the twin 50-cm telescopes, respectively. Note the
pixel sizes were 0.429 and 0.6 arcsec for the Mephisto and 50-cm image frames.

(3) Point Spread Function (PSF) model construction: we then constructed the
PSF model for each image after alignment using SExtractor (Bertin & Arnouts,
1996) and PSFex (Bertin, 2011), and acquired the PSF at the position of SN
2023ixf.

(4) Image subtraction and PSF photometry: After conducting mutual PSF
convolution on both target images and reference images for image subtraction,
we obtained the subtracted images by subtracting target images from reference
image, and performed PSF photometry to construct the light curves.

In Figure 2, we plot the images of SN 2023ixf with Mephisto and the twin 50-cm
telescopes in $uvgriz$ bands, the middle panels and the bottom panels
correspond to the images of SN 2023ixf region on 2023 May 21 and 2023 June 4,
respectively. After obtaining the differential photometric measurements, we
further corrected the magnitudes for the interstellar extinction. The
foreground extinction from the Milky Way in the line of sight of SN 2023ixf is
$E(B-V)_{\rm MW}$= 0.008 mag (Schlegel et al., 1998; Schlafly & Finkbeiner,
2011). For the host galaxy extinction, we used the result of Liu et al. (2023)
obtained by analyzing the spectral data from the Hobby Eberly Telescope Dark
Energy Experiment (HETDEX), who obtained an extinction value of $E(B-V)_{\rm
host}=0.06\pm 0.14$ mag that is slightly larger than $E(B-V)=0.031~{}{\rm
mag}$ given by some previous works (Smith et al., 2023; Teja et al., 2023).
Using the extinction law of Cardelli et al. (1989) and assuming $R_{V}$ = 3.1,
we obtain the extinction values of 0.338, 0.316, 0.221, 0.183, 0.117 and 0.095
mag accounting for both the Milky Way and host galaxy for the $uvgriz$ bands,
respectively.

Figure 3: Multiband light curves of SN 2023ixf obtained with Mephisto and the
twin 50-cm telescopes. The photometry data of Mephisto and the twin 50-cm
telescopes is shown in the Appendix. Offsets have been added to the magnitudes
of different bands for clarity, as specified in the legend. Figure 4: The
comparison of light curves in $g$ (green points) and $r$ (yellow points) bands
between this work and other previous works. The data from other previous works
(Perley & Irani, 2023; Kendurkar & Balam, 2023a; Fowler et al., 2023;
Zimmerman et al., 2024). Offsets have been added to the magnitudes of
different bands for clarity, as specified in the legend. Figure 5: Spectral
energy distributions (SEDs) at 2.9, 9.9, 16.9 days after phase zero. Circles
and triangles correspond to apparent magnitudes measured with the Mephisto and
the twin 50-cm telescopes, respectively. The green, red, and pink lines
correspond to best-fit blackbody spectra of effective temperatures
$T=25000,13000,9400~{}{\rm K}$, respectively. The wavelength of the data in
this figure is taken as the mean wavelength of the filter.

In Figure 3, we present the observed light curves of SN 2023ixf with Mephisto
and the twin 50-cm telescopes in $uvgriz$ bands (the data behind Figure 3 are
shown in the appendix, and we should notice that the uncertainties in the
appendix mainly include the photon-counting uncertainties. The uncertainties
of the photometric calibration and the zero points of magnitude are
approximately $0.01~{}{\rm mag}$). All photometric data are in AB magnitudes
and have been corrected for the Milky Way and host galaxy extinctions. Since
the measurement errors of Mephisto are much smaller than those of the twin
50-cm telescopes, for $gr$ bands, we only include the Mephisto measurements in
this work. The Mephisto measurements show that SN 2023ixf has peak magnitudes
$m_{u}=10.59$ mag, $m_{v}=10.71$ mag, $m_{g}=11.14$ mag, and $m_{r}=11.33$ mag
at $\sim 3.9$ days after phase zero and decline gradually after the explosion.
The rise time (post-explosion) of SN 2023ixf is significantly shorter than the
average rise time of other normal Type II events (c.f. $\sim$10 days, see
Valenti et al., 2016). The comparison of light curves in $g$ and $r$ bands
between this work and other previous works (Perley & Irani, 2023; Kendurkar &
Balam, 2023a; Fowler et al., 2023; Zimmerman et al., 2024) are shown in Figure
4. In Figure 5, we plot the spectral energy distribution (SED) at 2.9, 9.9,
and 16.9 days after phase zero and fit them with a blackbody. The mean
wavelengths of the $uvgriz$ bands are $3449.95$, $3888.79$, $5273.22$,
$6253.80$, $8301.75$, and $9368.17$Å, respectively. One can see that the
effective temperature evolves significantly during the early phase of SN
2023ixf.

##  3 Evolution of Bolometric Luminosity, Effective Temperature and
Photospheric Radius

In this section, we discuss the evolving properties of SN 2023ixf. The
evolution of an SN could be well described by an isotropic expanding fireball
in the early phase. For an SN ejecta with a time-dependent mean density
$\rho(t)$, the evolution of the photospheric radius could be described by
(e.g., Arnett, 1982; Liu et al., 2018),

$\displaystyle R_{\rm ph}(t)=R(t)-\frac{2}{3}\lambda(t),$ (1)

where $\lambda(t)=1/[\kappa(t)\rho(t)]$ the mean free path of photons and
$\kappa$ the opacity of the SN ejecta. We should notice that the opacity
$\kappa$ of Type II SNe could evolve due to the hydrogen recombination
process. The SN ejecta enters a homologous expansion phase after a few times
of the expansion timescale $R_{0}/v$, where $v$ is the ejecta velocity and
$R_{0}$ the progenitor radius. At the early phase of SN expansion, the mean
free path $\lambda(t)$ is much smaller than the ejecta radius $R(t)$,
resulting in a photosphere that is homologously expanding, $R_{\rm
ph}(t)\simeq R(t)$. As the ejecta density decreases with the expansion, the
photospheric radius reaches its maximum at the transitional timescale $t_{\rm
tr}$ with $dR_{\rm ph}(t_{\rm tr})/dt=0$ (e.g., Liu et al., 2018). The
photosphere then enters a late declining phase at $t>t_{\rm tr}$.

Assuming that the blackbody radiation dominates the SN emission, we can derive
the bolometric luminosity from the multiband photometry at each epoch and
infer the effective temperature by fitting the SED at the same epoch. First,
the AB magnitude system is defined based on the observed flux density,

$\displaystyle m_{\rm AB,\nu}=-2.5\log F_{\nu}-48.6.$ (2)

For a fireball of uniform brightness of a photospheric radius $R_{\rm ph}$ and
a radiation intensity $B_{\nu}$, the flux density at distance $d$ is
$F_{\nu}=\pi B_{\nu}(R_{\rm ph}/d)^{2}$, where the intensity of the blackbody
radiation satisfies the Planck law,

$\displaystyle B_{\nu}(T_{\rm
eff},\nu)=\frac{2h\nu^{3}}{c^{2}}\frac{1}{\exp(h\nu/kT_{\rm eff})-1},$ (3)

where $T_{\rm eff}$ is the effective temperature of the SN ejecta. We consider
that the photometry is performed in two bands denoted by $i=1,2$ and the
measured AB magnitude in a band of frequency $\nu_{i}$ is $m_{{\rm
AB},\nu_{i}}$ ($\nu_{1}<\nu_{2}$). The color between band 1 and band 2 is,

$\displaystyle\Delta m_{\rm AB,\nu_{21}}=m_{\rm AB,\nu_{2}}-m_{\rm
AB,\nu_{1}}=-2.5\log\left[\frac{B_{\nu}(T_{\rm eff},\nu_{2})}{B_{\nu}(T_{\rm
eff},\nu_{1})}\right].$ (4)

The observed evolution of SN 2023ixf in the $(u-g)-(v-r)$ color-color diagram
is shown in Figure 6. It indicates that the radiation is well approximated by
blackbody radiation with some deviations at the later epochs. It is
interesting that the observed color-color diagram in the later epochs is
distributed on both sides of the theoretical prediction of blackbody radiation
with a turning point occurring at $\sim 90$ days. Such a turning feature is
attributed to the effective temperature slightly rising after 90 days, see the
following discussion.

Figure 6: The evolution of SN 2023ixf in the $(u-g)-(v-r)$ color-color
diagram. The epoch of the measurement after phase zero with Mephisto is
represented by the color of the data point. The solid line corresponds to the
theoretical prediction of blackbody radiation based on Eq.(4).

Let $L_{\nu}$ be the specific luminosity at frequency $\nu$. According to the
Planck law, the bolometric luminosity $L$ is given by,

$\displaystyle L=\frac{\pi^{4}}{15}\left(\frac{kT_{\rm
eff}}{h\nu}\right)^{4}\left[\exp\left(\frac{h\nu}{kT_{\rm
eff}}\right)-1\right]\nu L_{\nu}.$ (5)

For $h\nu\ll kT_{\rm eff}$, one approximately has $L\simeq(\pi^{4}/15)(kT_{\rm
eff}/h\nu)^{3}\nu L_{\nu}$. Using $F_{\nu}=L_{\nu}/4\pi d^{2}$, the AB
magnitude at frequency $\nu$ could be written as,

$\displaystyle m_{\rm
AB,\nu}=-2.5\log\left[\frac{15}{4\pi^{5}}\frac{L}{d^{2}\nu}\frac{(h\nu/kT_{\rm
eff})^{4}}{\exp(h\nu/kT_{\rm eff})-1}\right]-48.6.$ (6)

For a given SED (i.e., the apparent magnitude as a function of frequency) at
time $t$, the bolometric luminosity $L(t)$ and the effective temperature
$T_{\rm eff}(t)$ could be fitted based on the above relation once the distance
$d$ is specified. Furthermore, for the blackbody radiation, the photospheric
radius at time $t$ can be derived by,

$\displaystyle R_{\rm ph}(t)=\sqrt{\frac{L(t)}{4\pi\sigma T_{\rm
eff}(t)^{4}}},$ (7)

where $\sigma=2\pi^{5}k^{4}/15c^{2}h^{3}=5.67\times 10^{-5}~{}{\rm
erg~{}cm^{-1}s^{-1}K^{-4}}$ the Stefan-Boltzmann constant. At last, we should
notice that for broad filters as shown in Figure 1, accounting for the
different widths of each filter, it would be more appropriate to convolve the
passbands of the filters with the SED of the blackbody radiation instead of
using a certain frequency.

Figure 7: The evolution of bolometric luminosity (top panel), effective
temperature (middle panel), and photospheric radius of SN 2023ixf. The blue
points correspond to the data measured with Mephisto and the twin 50-cm
telescopes, as shown in Table LABEL:tabevo of the Appendix. The green points
correspond to the data from Zimmerman et al. (2024), which are shown for
comparison. The red dashed line in the bolometric luminosity evolution (top
panel) indicates the energy deposition from the best-fit 56Ni mass after the
plateau. The red dashed line in the photospheric radius evolution (bottom
panel) indicates the homologous expansion of the photosphere before hydrogen
recombination.

Based on the expanding fireball model, the evolution of bolometric luminosity
(top panel), effective temperature (middle panel), and photospheric radius
(bottom panel) are shown in Figure 7 with the corresponding data in Table
LABEL:tabevo of the Appendix. In doing so we used the data of the Mephisto and
the twin 50-cm telescopes and combined the measurements on the same date and
calculated the mean value and the standard deviation. We find that the
bolometric luminosity reached a maximum value of $L\sim~{}3\times
10^{43}~{}{\rm erg~{}s^{-1}}$ at 3.9 days after phase zero, which is $\sim
45\%$ of the maximum luminosity given by Zimmerman et al. (2024). Such a
deviation might be due to the following reasons: 1) the maximum luminosity of
Zimmerman et al. (2024) has a relatively large uncertainty, i.e.,
$\log(L/10^{42}~{}{\rm erg~{}s^{-1}})=68.59\pm 78.18$, see the Supplementary
Table 8 of Zimmerman et al. (2024). The maximum luminosity measured in this
work is actually in the uncertainty range of Zimmerman et al. (2024). 2)
Zimmerman et al. (2024) used UV filters from Swift, while the Mephisto dataset
went as blue as the $u$ band. The different observed band coverages between
the two facilities cause a systematic deviation of the temperature measurement
(also see Faran et al., 2018, as an example showing this issue), finally
leading to the bolometric luminosity deviation. The bolometric luminosity
evolution shows a plateau phase in the first 90 days after the explosion.
After that, the light curve fully settled onto the radioactive tail. This
feature implies a hydrogen recombination process in the first 90 days, which
is also consistent with the observation of Zimmerman et al. (2024). We find
that the measured bolometric luminosity in the first month is well consistent
with that of Zimmerman et al. (2024) but becomes larger than that of Zimmerman
et al. (2024) after the first month, meanwhile, for our measurement, the
uncertainties of the bolometric luminosity after the first month are larger
than those in the first month. The main reason is that the peak wavelength of
the blackbody radiation has significantly shifted out from our observed bands
after the first month, leading to a systematic deviation and large measurement
uncertainties of the effective temperature and the bolometric luminosity, also
see the SED evolution of Figure 5. The effective temperature shows a
continuous decline in the first two months and gradually tends towards a
constant in the following observation, as shown in the middle panel of Figure
7. The maximum effective temperature reaches $3.2\times 10^{4}~{}{\rm K}$ at
the first observation epoch and tends towards $\sim(3000-4000)~{}{\rm K}$
after the first two months. We also notice that the effective temperature
slightly rises after 90 days (consistent with the turning feature in the
color-color diagram, see Figure 6), although the data has relatively large
uncertainties during this period. Similar to the evolution of the bolometric
luminosity, due to the limit observed band range, the measured effected
temperature in the first month is consistent with that of Zimmerman et al.
(2024) but becomes lower than that of Zimmerman et al. (2024) after the first
month. The evolution of photospheric radius presents a homologous expansion in
the first two months and significantly shrinks after that. The photospheric
radius in the homologous expansion phase is given by,

$\displaystyle R_{\rm ph}(t)=R_{\ast}+v_{\rm ej}(t-t_{\ast}),$ (8)

for $t>t_{\ast}$, where $R_{\ast}$ and $t_{\ast}$ are the initial radius and
time for homologous expansion, respectively, and $v_{\rm ej}$ is the ejecta
velocity. Based on the above equation, we fit the evolution of the
photospheric radius in the expansion phase. The best-fit result is shown in
the red dashed line in the bottom panel of Figure 7 and the photospheric
evolution is consistent with a homologous expansion with

$\displaystyle R_{\ast}\simeq 722R_{\odot},~{}t_{\ast}\simeq 0.32~{}{\rm
days},~{}v_{\rm ej}\simeq 8.7\times 10^{3}~{}{\rm km~{}s^{-1}}.$ (9)

The photospheric velocity is consistent with previous works (e.g., Zimmerman
et al., 2024), but the initial radius is smaller than that of Zimmerman et al.
(2024) that involved the constant-radius value as the shock-breakout radius of
the SN evolution.

##  4 Physical Properties of SN 2023ixf

In this section, we constrain the physical properties (e.g., the ejected mass
$M_{\rm ej}$, explosion energy $E$, initial 56Ni mass, etc.) of SN 2023ixf
based on the observed multi-wavelength light curves. For Type II SN, once the
outer layers of ejecta cool below $T_{i}\simeq 6000~{}{\rm K}$, the hydrogen
recombination process will occur and the electron scattering opacity will drop
by several orders of magnitude. In this case, the neutral material above the
ionization front is transparent, and ionized material inside the front is
opaque, i.e., $\kappa\sim{\rm const}$ for $T>T_{i}$ and $\kappa\sim 0$ for
$T<T_{i}$, and the photosphere is nearly coincident with the ionization front.
As radiation escapes, the ionization front recedes inward in the ejecta’s
comoving frame. When the ionization front reaches the base of the hydrogen
envelope, the internal energy will be largely depleted, leading to the end of
the plateau where the light curve drops off sharply. We find that the
evolution of the bolometric luminosity, effective temperature, and
photospheric radius support the above physical picture: the light curve shows
a plateau phase in the first 90 days and fully settles onto the radioactive
tail subsequently, meanwhile, the effective temperature tends towards a
constant and the photospheric radius shrinks at $\sim(50-60)~{}{\rm days}$
after the explosion. An approximate analytic scaling rule for Type II SNe has
been derived for both the luminosity $L_{p}$ and the duration $\tau_{p}$ of
the plateau (Popov, 1993; Kasen & Woosley, 2009; Sukhbold et al., 2016).
Calibrating the analytic scaling rule to a set of numerical models, the
luminosity and duration of the plateau are given by (Kasen & Woosley, 2009;
Sukhbold et al., 2016),

$\displaystyle L_{p,50}\simeq 1.26\times 10^{42}~{}{\rm
erg~{}s^{-1}}E_{51}^{5/6}M_{\rm ej,10}^{-1/2}R_{0,500}^{2/3},$ (10)
$\displaystyle t_{p}\simeq 122~{}{\rm day}E_{51}^{-1/4}M_{\rm
ej,10}^{1/2}R_{0,500}^{1/6},$ (11)

where $M_{\rm ej,10}=M_{\rm ej}/10M_{\odot}$, $R_{0,500}=R_{0}/500R_{\odot}$,
$L_{p,50}$ is the plateau luminosity at 50 days, and the helium mass fraction
is assumed to be $X_{\rm He}=0.33$ here. Thus, the explosion energy $E$ and
the ejecta mass $M_{\rm ej}$ could be estimated by the above approximate
analytic scaling rules. In this work, the plateau luminosity of SN 2023ixf at
50 days is measured to be $L_{p,50}\simeq 4\times 10^{42}~{}{\rm
erg~{}s^{-1}}$ (see the top panel of Figure 7), and the plateau duration is
estimated to be $t_{p}\simeq 90~{}{\rm day}$ (also see Zimmerman et al.,
2024). The progenitor radius is taken as $R_{0}\simeq(410-1400)R_{\odot}$
based on the bolometric luminosity and the effective temperature of the
progenitor (Niu et al., 2023; Hosseinzadeh et al., 2023; Jencson et al., 2023;
Kilpatrick et al., 2023; Soraisam et al., 2023; Xiang et al., 2023; Qin et
al., 2023). Using Eq.(10) and Eq.(11), the explosion energy and the ejecta
mass are constrained to be,

$\displaystyle E\simeq(1.0-5.7)\times 10^{51}~{}{\rm erg},$ (12)
$\displaystyle M_{\rm ej}\simeq(3.8-13.9)M_{\odot}.$ (13)

We notice that the uncertainties of $E$ and $M_{\rm ej}$ are mainly attributed
to the different measurements of the progenitor radius $R_{0}$ in the
literature.

In addition to the method that uses the scaling rule between $L_{p}$ and
$t_{p}$, the ejecta mass can also be measured by the time-weighted integrated
luminosity removing the contribution from the initial 56Ni. Since there is a
clear distinction at 90 days between the photospheric phase and the
radioactive tail in the light curve of SN 2023ixf, as shown in the top panel
of Figure 7 (also see Zimmerman et al., 2024) the contributions of the cooling
envelope and 56Ni decay to the photospheric emission could be separated based
on the measurement of the time-weighted integrated bolometric luminosity (Katz
et al., 2013; Nakar et al., 2016). We define the internal energy as $E_{\rm
int}(t)$ and the input power by the radioactive decay as $Q_{\rm Ni}(t)$. For
a homologously expanding ejecta, the derivative of the internal energy is,

$\displaystyle\frac{dE_{\rm int}(t)}{dt}=-\frac{E_{\rm int}(t)}{t}+Q_{\rm
Ni}(t)-L(t),$ (14)

where $E_{\rm int}(t)/t$ corresponds to the loss rate of the internal energy
due to the adiabatic expansion, $L(t)$ the bolometric luminosity. The input
power by the radioactive decay is given by(Arnett, 1982; Chatzopoulos et al.,
2012),

$\displaystyle Q_{\rm Ni}(t)=M_{\rm Ni}\left[(\epsilon_{\rm Ni}-\epsilon_{\rm
Co})e^{-t/t_{\rm Ni}}+\epsilon_{\rm Co}e^{-t/t_{\rm Co}}\right],$ (15)

where $M_{\rm Ni}$ the initial nickel mass of the SN ejecta, $t_{\rm
Ni}=8.8~{}{\rm days}$, $t_{\rm Co}=111.3~{}{\rm days}$, $\epsilon_{\rm
Ni}=3.9\times 10^{10}~{}{\rm erg~{}s^{-1}g^{-1}}$ and $\epsilon_{\rm
Co}=6.8\times 10^{9}~{}{\rm erg~{}s^{-1}g^{-1}}$ are the energy generation
rates due to Ni and Co decays, respectively. At $t>t_{p}$, the diffusion time
through the envelope is much shorter than $t$, leading to $L(t>t_{p})=Q_{\rm
Ni}(t>t_{p})$. Therefore, the initial 56Ni mass can be measured by the
observed radioactive tail after 90 days. In the top panel of Figure 7, we fit
the bolometric luminosity after 90 days using Eq.(15) and obtain an initial
56Ni mass,

$\displaystyle M_{\rm Ni}\simeq 0.098M_{\odot},$ (16)

which is 27% larger than $M_{\rm Ni}\simeq 0.071M_{\odot}$ given by Zimmerman
et al. (2024). Using the partial integration for Eq.(14), one has (Katz et
al., 2013; Nakar et al., 2016),

$\displaystyle ET\equiv E_{\rm
int}(t_{\ast})t_{\ast}=\int_{0}^{t_{p}}t[L(t)-Q_{\rm Ni}(t)]dt,$ (17)

where $t_{\ast}$ the time at which the homologous expansion phase begins
(Nakar et al., 2016). Since the initial 56Ni mass has been measured by the
radioactive tail, i.e., $M_{\rm Ni}=0.098M_{\odot}$. Using the bolometric
luminosity evolution $L(t)$ and taking $t_{p}=90~{}{\rm day}$, we obtain

$\displaystyle ET\simeq 7.7\times 10^{55}~{}{\rm erg~{}s}.$ (18)

On the other hand, as an observable quantity, $ET$ satisfies $ET\propto
ER_{0}/v_{\rm ej}\propto M_{\rm ej}R_{0}v_{\rm ej}$, which depends on $M_{\rm
ej}$, $R_{0}$, and $v_{\rm ej}$ and is insensitive to the exact details of
radiation transport and CSM mass. The simulation of a large set of SN
progenitors suggests a scaling relation of (Shussman et al., 2016)

$\displaystyle ET\simeq 0.1M_{\rm ej}R_{0}v_{\rm ej}.$ (19)

The progenitor radius has been measured to be $R_{0}\simeq(410-1400)R_{\odot}$
based on the bolometric luminosity and the effective temperature of the
progenitor (Niu et al., 2023; Hosseinzadeh et al., 2023; Jencson et al., 2023;
Kilpatrick et al., 2023; Soraisam et al., 2023; Xiang et al., 2023; Qin et
al., 2023). The ejecta velocity is measured to be $v_{\rm ej}\simeq 8.7\times
10^{3}~{}{\rm km~{}s^{-1}}$ based on the evolution of the photospheric radius
in the early stage. Thus, the ejecta mass is estimated to be

$\displaystyle M_{\rm ej}\simeq\frac{ET}{0.1R_{0}v_{\rm
ej}}\simeq(4.7-16)M_{\odot},$ (20)

which is approximately consistent with $M_{\rm ej}\simeq(3.8-13.9)M_{\odot}$
given by the scaling rule.

The peak bolometric luminosity of SN 2023ixf is $L_{0}\simeq 3\times
10^{43}~{}{\rm erg~{}s^{-1}}$ at $t_{0}\simeq 3.9~{}{\rm days}$ after the
explosion, which has been proposed to be caused by the interaction between the
SN ejecta and the circumstellar medium (CSM). Assuming that the CMS density is
$\rho_{\rm CSM}$ and the peak bolometric luminosity $L_{0}$ corresponds to the
kinetic energy of the shock caused by the ejecta-CSM interaction,
$L_{0}t_{0}\sim(1/2)M_{\rm CSM}v_{\rm ej}^{2}$, where the shock medium is
dominated by the swept CSM, one has the mass of the shocked CSM of

$\displaystyle M_{\rm CSM}\sim\frac{2L_{0}t_{0}}{v_{\rm ej}^{2}}\simeq
0.013M_{\odot}.$ (21)

The CSM density is estimated by $M_{\rm CSM}\sim(4\pi/3)(v_{\rm
ej}t_{0})^{3}\rho_{\rm CSM}$, leading to

$\displaystyle\rho_{\rm CSM}\sim\frac{3L_{0}}{2\pi v_{\rm
ej}^{5}t_{0}^{2}}\simeq 2.5\times 10^{-13}~{}{\rm
g~{}cm^{-3}}L_{0,{43.5}}t_{\rm 0,3.9day}^{-2},$ (22)

where $t_{\rm 0,3.9day}=t_{0}/(3.9~{}{\rm day})$ and the ejecta velocity is
taken as $v_{\rm ej}\simeq 8700~{}{\rm km~{}s^{-1}}$. The mass loss rate of
the stellar wind generating the CSM by the progenitor is,

$\displaystyle\dot{M}\sim 4\pi(v_{\rm ej}t_{0})^{2}\rho_{\rm CSM}v_{w}\simeq
0.022M_{\odot}~{}{\rm yr^{-1}}L_{0,{43.5}},$ (23)

where the progenitor wind velocity is assumed to be $v_{w}=50~{}{\rm
km~{}s^{-1}}$ as the typical value. The above CMS density and the mass loss
rate of the progenitor are consistent with the results of Jacobson-Galan et
al. (2023) and Zimmerman et al. (2024). There are some possible ways to form
the CSM near the SN progenitor as proposed by Branch & Wheeler (2017): 1) the
fast wind of the massive progenitor produces low-density bubbles surrounded by
the swept-up interstellar matter. 2) an episodic matter ejection from the
progenitor (or from a common-envelope episode of a binary system) forms the
detached CSM shell. 3) the fast wind of the progenitor that has returned to
the blue compresses the previous red-supergiant wind into a shell.

##  5 Discussions and Conclusions

In this paper, we presented the multi-wavelength simultaneous photometric
observation of SN 2023ixf located in the nearby spiral host galaxy M101 at
$d=6.85~{}{\rm Mpc}$ in the first 283 days after the explosion. Based on the
measurements of the Mephisto and the twin 50-cm telescopes, we calculated and
analyzed the evolution of the bolometric luminosity, effective temperature,
and photospheric radius. The following conclusions for SN 2023ixf are drawn:

The measurements with the Mephisto showed that the peak apparent magnitudes of
SN 2023ixf were $m_{u}=10.59$, $m_{v}=10.71$, $m_{g}=11.14$ and $m_{r}=11.33$
at 3.9 days after phase zero and the brightness declined in the following
observation. We find that there is a significant drop in the light curve
between 59 days and 90 days, which is consistent with the plateau end reported
by Zimmerman et al. (2024). Based on the multi-wavelength photometric data, we
derived the evolution of the bolometric luminosity, effective temperature, and
photospheric radius. The bolometric luminosity reached a maximum value of
$L\sim~{}3\times 10^{43}~{}{\rm erg~{}s^{-1}}$ at 3.9 days after phase zero
and fully settled onto the radiative tail at $\sim 90~{}{\rm days}$. The
effective temperature has been a maximum ($\gtrsim 3.2\times 10^{4}~{}{\rm
K}$) at the first observation epochs and approached to a constant of
$(3000-4000)~{}{\rm K}$ from 60 days to 283 days. The early-phase photospheric
radius evolution is consistent with a homologous expansion with an initial
radius of $R_{\ast}\simeq 722R_{\odot}$ and an ejecta velocity of $v_{\rm
ej}\simeq 8.7\times 10^{3}~{}{\rm km~{}s^{-1}}$ and gradually shrunk 60 days
after the explosion. The above features of the bolometric luminosity,
effective temperature, and photospheric radius suggest that SN 2023ixf
represented a significant hydrogen recombination process in the first three
months.

Since the light curve showed a significant radiative tail after $\sim
90~{}{\rm days}$, we estimated the initial nickel mass in the SN ejecta as
$M_{\rm Ni}\sim 0.098M_{\odot}$, which is 27% larger than the result of
Zimmerman et al. (2024). We first estimated the explosion energy $E$ and the
ejecta mass $M_{\rm ej}$ based on the scaling rule of Type II SNe given by
Kasen & Woosley (2009) and obtained $E\simeq(1.0-5.7)\times 10^{51}~{}{\rm
erg}$ and $M_{\rm ej}\simeq(3.8-13.9)M_{\odot}$, respectively. On the other
hand, due to the existence of the radiative tail in the light curve of SN
2023ixf, we can separate the contributions of the cooling envelope and 56Ni
decay to the photospheric emission based on the measurement of the time-
weighted integrated bolometric luminosity (Katz et al., 2013; Nakar et al.,
2016). In this case, the mass of the SN ejecta is estimated to be $M_{\rm
ej}\sim(4.7-16)M_{\odot}$. We propose that the peak bolometric luminosity is
caused by the interaction between the ejecta and the circumstellar medium
(CSM). In this scenario, the shocked CSM mass is $M_{\rm CSM}\sim
0.013M_{\odot}$, the CSM density is $\rho_{\rm CSM}\sim 2.5\times
10^{-13}~{}{\rm g~{}cm^{-3}}$ and the mass loss rate of the progenitor is
$\dot{M}\sim 0.022M_{\odot}~{}{\rm yr^{-1}}$.

Mephisto is developed at and operated by the South-Western Institute for
Astronomy Research of Yunnan University (SWIFAR-YNU), funded by the “Yunnan
University Development Plan for World-Class University” and “Yunnan University
Development Plan for World-Class Astronomy Discipline”. The authors
acknowledge supports from the “Science & Technology Champion Project”
(202005AB160002) and from two “Team Projects” – the “Innovation Team”
(202105AE160021) and the “Top Team” (202305AT350002), all funded by the
“Yunnan Revitalization Talent Support Program”. Y.P.Y. is supported by the
National Natural Science Foundation of China grant No.12003028 and the
National SKA Program of China (2022SKA0130100). X.K.L. acknowledges the
supports from NSFC of China under grant No. 12173033, National Key R&D Program
of China No. 2022YFF0503403, and YNU grant No. C176220100008. Y.-Z. Cai is
supported by the National Natural Science Foundation of China (NSFC, Grant No.
12303054), the Yunnan Fundamental Research Projects (Grant No. 202401AU070063)
and the International Centre of Supernovae, Yunnan Key Laboratory (No.
202302AN360001). We thank the anonymous referee for providing helpful comments
and suggestions that have allowed us to improve this manuscript significantly.
We also acknowledge the helpful discussions with Liang-Duan Liu, Jin-Ping Zhu,
Weili Lin, Erez Zimmerman and Andrea Reguitti (INAF-OAPd).

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In this appendix, we provide the photometry data of Mephisto (Table
LABEL:tabm) and the twin 50-cm telescopes (Table LABEL:tabf) as the data
behind Figure 3. The best-fit results of bolometric luminosity, effective
temperature, and photospheric radius for blackbody radiation are shown in
Table LABEL:tabevo as the data behind Figure 7.

Table 1: Photometry data of SN 2023ixf with Mephisto in $ug$ and $vr$ bands. This table is available in its entirety in the online supplementary material, and the full table can also be found at the ScienceDB https://doi.org/10.57760/sciencedb.15753. Notice that the uncertainties in the table mainly include the photon-counting uncertainties. The uncertainties of the photometric calibration and the zero points of magnitude are approximately $0.01~{}{\rm mag}$. MJD/day | u/mag | g/mag | v/mag | r/mag
---|---|---|---|---
60084.70538 | – | 12.448${\pm}$0.001 | – | –
60084.70539 | 11.858${\pm}$0.001 | – | – | –
60084.70627 | – | 12.463${\pm}$0.001 | – | –
60084.70628 | 11.866${\pm}$0.001 | – | – | –
60084.70735 | – | 12.463${\pm}$0.001 | – | –
60084.70736 | 11.858${\pm}$0.001 | – | – | –
60084.70846 | 11.867${\pm}$0.001 | – | – | –
60084.70932 | 11.863${\pm}$0.001 | – | – | –
60084.71094 | – | – | 12.004${\pm}$0.002 | –
60084.71179 | – | – | 12.008${\pm}$0.002 | –
… | … | … | … | …
60354.93491 | – | – | – | 15.702${\pm}$0.008
60354.93715 | – | – | – | 15.695${\pm}$0.008
60354.93939 | – | – | 18.14${\pm}$0.03 | –
60354.93941 | – | – | – | 15.694${\pm}$0.008
60354.94166 | – | – | – | 15.706${\pm}$0.008
60364.93336 | – | – | 18.18${\pm}$0.03 | 15.786${\pm}$0.008
60364.93560 | – | – | – | 15.809${\pm}$0.008
60364.93771 | – | – | 18.28${\pm}$0.03 | –
60364.93785 | – | – | – | 15.796${\pm}$0.008
60364.94009 | – | – | – | 15.796${\pm}$0.008
Table 2: Photometry data of SN 2023ixf with the twin 50-cm telescopes in $iz$ band. This table is available in its entirety in the online supplementary material, and the full table can also be found at the ScienceDB https://doi.org/10.57760/sciencedb.15753. Notice that the uncertainties in the table mainly include the photon-counting uncertainties. The uncertainties of the photometric calibration and the zero points of magnitude are approximately $0.01~{}{\rm mag}$. MJD/day | i/mag | z/mag
---|---|---
60084.66164 | 13.423${\pm}$0.005 | –
60084.66464 | – | 13.58${\pm}$0.01
60084.85436 | 13.067${\pm}$0.003 | –
60085.65457 | 12.280${\pm}$0.002 | –
60085.65757 | 12.291${\pm}$0.002 | –
60085.65759 | – | 12.459${\pm}$0.006
60085.74509 | 12.220${\pm}$0.002 | –
60085.74809 | 12.221${\pm}$0.002 | –
60085.85156 | 12.156${\pm}$0.002 | –
60085.85160 | – | 12.361${\pm}$0.006
… | … | …
60096.62810 | 11.383${\pm}$0.001 | –
60096.62811 | – | 11.496${\pm}$0.003
60097.62223 | 11.395${\pm}$0.001 | 11.503${\pm}$0.003
60097.62383 | 11.394${\pm}$0.001 | 11.488${\pm}$0.003
60098.62184 | 11.393${\pm}$0.001 | –
60098.62341 | 11.398${\pm}$0.001 | –
60098.62344 | – | 11.503${\pm}$0.003
60099.61574 | – | 11.502${\pm}$0.003
60099.61575 | 11.412${\pm}$0.001 | –
60099.61734 | 11.412${\pm}$0.001 | 11.483${\pm}$0.003
Table 3: The best-fit results of bolometric luminosity, effective temperature, and photospheric radius for blackbody radiation. MJD/day | $\log[L/{\rm erg~{}s^{-1}}]$ | $\log[T_{\rm eff}/{\rm K}]$ | $\log[R_{\rm ph}/{\rm cm}]$
---|---|---|---
60084.70734 | 43.29 $\pm$ 0.10 | 4.507 $\pm$ 0.042 | 14.206 $\pm$ 0.099
60085.70783 | 43.45 $\pm$ 0.04 | 4.401 $\pm$ 0.018 | 14.498 $\pm$ 0.044
60086.67782 | 43.49 $\pm$ 0.06 | 4.357 $\pm$ 0.028 | 14.603 $\pm$ 0.064
60087.67758 | 43.41 $\pm$ 0.04 | 4.305 $\pm$ 0.020 | 14.673 $\pm$ 0.045
60090.65298 | 43.15 $\pm$ 0.01 | 4.175 $\pm$ 0.011 | 14.802 $\pm$ 0.024
60091.62564 | 43.08 $\pm$ 0.02 | 4.137 $\pm$ 0.013 | 14.838 $\pm$ 0.029
60092.71010 | 43.03 $\pm$ 0.01 | 4.106 $\pm$ 0.007 | 14.876 $\pm$ 0.015
60093.74334 | 42.98 $\pm$ 0.01 | 4.080 $\pm$ 0.004 | 14.901 $\pm$ 0.009
60094.71458 | 42.94 $\pm$ 0.01 | 4.056 $\pm$ 0.005 | 14.931 $\pm$ 0.011
60095.68900 | 42.90 $\pm$ 0.01 | 4.035 $\pm$ 0.005 | 14.955 $\pm$ 0.012
60096.69822 | 42.87 $\pm$ 0.01 | 4.015 $\pm$ 0.005 | 14.979 $\pm$ 0.011
60097.67836 | 42.84 $\pm$ 0.01 | 3.999 $\pm$ 0.006 | 14.996 $\pm$ 0.014
60098.59604 | 42.84 $\pm$ 0.01 | 3.998 $\pm$ 0.008 | 14.997 $\pm$ 0.017
60099.68435 | 42.78 $\pm$ 0.01 | 3.972 $\pm$ 0.007 | 15.023 $\pm$ 0.016
60101.61025 | 42.74 $\pm$ 0.01 | 3.945 $\pm$ 0.017 | 15.052 $\pm$ 0.036
60113.66383 | 42.54 $\pm$ 0.06 | 3.769 $\pm$ 0.031 | 15.306 $\pm$ 0.070
60121.66017 | 42.55 $\pm$ 0.11 | 3.677 $\pm$ 0.035 | 15.496 $\pm$ 0.089
60125.60418 | 42.60 $\pm$ 0.12 | 3.638 $\pm$ 0.031 | 15.597 $\pm$ 0.087
60126.59941 | 42.58 $\pm$ 0.13 | 3.635 $\pm$ 0.035 | 15.595 $\pm$ 0.097
60141.55753 | 42.67 $\pm$ 0.14 | 3.557 $\pm$ 0.027 | 15.797 $\pm$ 0.090
60172.56913 | 42.03 $\pm$ 0.07 | 3.526 $\pm$ 0.012 | 15.537 $\pm$ 0.043
60173.58373 | 42.01 $\pm$ 0.07 | 3.526 $\pm$ 0.012 | 15.525 $\pm$ 0.043
60190.53759 | 41.97 $\pm$ 0.09 | 3.514 $\pm$ 0.018 | 15.529 $\pm$ 0.059
60191.53887 | 41.88 $\pm$ 0.10 | 3.537 $\pm$ 0.020 | 15.442 $\pm$ 0.067
60192.53781 | 41.88 $\pm$ 0.10 | 3.534 $\pm$ 0.017 | 15.448 $\pm$ 0.062
60193.54465 | 41.88 $\pm$ 0.09 | 3.534 $\pm$ 0.017 | 15.445 $\pm$ 0.060
60195.56868 | 41.86 $\pm$ 0.11 | 3.536 $\pm$ 0.019 | 15.432 $\pm$ 0.069
60201.52122 | 41.83 $\pm$ 0.10 | 3.538 $\pm$ 0.017 | 15.413 $\pm$ 0.062
60221.49577 | 41.80 $\pm$ 0.15 | 3.527 $\pm$ 0.030 | 15.423 $\pm$ 0.097
60274.95250 | 41.42 $\pm$ 0.13 | 3.559 $\pm$ 0.025 | 15.166 $\pm$ 0.083
60282.94518 | 41.35 $\pm$ 0.17 | 3.574 $\pm$ 0.038 | 15.100 $\pm$ 0.118
60307.87612 | 41.20 $\pm$ 0.12 | 3.583 $\pm$ 0.026 | 15.009 $\pm$ 0.083
60312.95936 | 41.19 $\pm$ 0.12 | 3.572 $\pm$ 0.025 | 15.026 $\pm$ 0.080
60313.96008 | 40.91 $\pm$ 0.15 | 3.637 $\pm$ 0.030 | 14.756 $\pm$ 0.096
60314.93569 | 41.12 $\pm$ 0.13 | 3.593 $\pm$ 0.030 | 14.950 $\pm$ 0.091
60320.96748 | 41.25 $\pm$ 0.15 | 3.560 $\pm$ 0.030 | 15.080 $\pm$ 0.096
60324.96763 | 41.04 $\pm$ 0.13 | 3.602 $\pm$ 0.029 | 14.892 $\pm$ 0.089
60331.95188 | 40.98 $\pm$ 0.14 | 3.613 $\pm$ 0.034 | 14.839 $\pm$ 0.101
60337.95158 | 40.95 $\pm$ 0.13 | 3.611 $\pm$ 0.030 | 14.829 $\pm$ 0.089
60354.93162 | 40.82 $\pm$ 0.13 | 3.632 $\pm$ 0.033 | 14.722 $\pm$ 0.094
60364.93665 | 40.94 $\pm$ 0.15 | 3.590 $\pm$ 0.030 | 14.867 $\pm$ 0.096