# Archiver System Management
for Belle II Detector Operation

Y.-K. Kim, S.-J. Cho, S.-H. Park, M. Nakao and T. Konno Y.-K. Kim, and
S.-J.Cho are with the Department of Physics, Yonsei University, Seoul,
Republic of Korea. (e-mail<EMAIL_ADDRESS>sjcho93@yonsei.ac.kr).S.-H.
Park, was with the Yonsei University, Seoul, Republic of Korea. He is now with
the KEK, Tsukuba, Japan (e-mail: seokhee.park@yonsei.ac.kr).M. Nakao is with
Institute of Particle and Nuclear Physics, KEK, Tsukuba, Japan (e-mail:
mikihiko.nakao@kek.jp).T. Konno is with Department of Physics, Kitasato
University, Sagamihara, Japan (e-mail: tkonno@kitasato-u.ac.jp).

###### Abstract

The Belle II experiment is a high-energy physics experiment at the SuperKEKB
electron-positron collider. Using Belle II data, high precision measurement of
rare decays and CP-violation in heavy quarks and leptons can be performed to
probe New Physics. In this paper, we present the archiver system used to store
the monitoring data of the Belle II detector and discuss in particular how we
maintain the system that archives the monitoring process variables of the
subdetectors. We currently save about 26 thousand variables including the
temperature of various subdetectors components, status of water leak sensors,
high voltage power supply status, data acquisition status, and luminosity
information of the colliding beams. For stable data taking, it is essential to
collect and archive these variables. We ensure the availability and
consistency of all the variables from the subdetector and other systems, as
well as the status of the archiver itself are consistent and regularly
updated. To cope with a possible hardware failure, we prepared a backup
archiver that is synchronized with the main archiver.

###### Index Terms:

Belle II, Monitoring

##  I Introduction

The Belle II experiment[1] at the SuperKEKB collider at KEK, Tsukuba, Japan,
is the latest collider experiment in high energy physics. SuperKEKB is an
accelerator that collides the 7.0 GeV electron beam with the 4.0 GeV positron
beam. The goal of Belle II is to collect 50 $\text{ab}^{-1}$ of integrated
luminosity, to measure rare decays and CP-violation in heavy quarks and
leptons with high precision, which provides unique probes for new physics
beyond the Standard Model. The Belle II detector consists of pixel detector
(PXD), silicon-strip vertex detector (SVD), central drift chamber (CDC), time
of propagation detector (TOP), aerogel ring-imaging cherenkov detector
(ARICH), electromagnetic calorimeter (ECL) and K-long and muon detector (KLM).

Our data acquisition (DAQ) system consists of various parts. Detector front-
end electronics (FEE) boards receive triggers and clock signal from the
unified trigger timing distribution (TTD) system with frontend timing switch
(FTSW) modules. Then digitized signal from the FEE boards, except for PXD, are
transferred to a unified readout boards called common pipelined platform for
electronics readout (COPPER) via a high speed optical link (Belle2link)[2].
The readout PC gathers data from the COPPER boards via Ethernet and send it to
high level trigger (HLT) input server where the event building is performed.

Belle II has started operation with full subdetectors in March 2019. One of
the essential task to ensure stable data-taking at Belle II is to collect and
archive various status of Belle II subdetectors. In this presentation, we
present the archiver management system of Belle II, including the experimental
physics and industrial control system (EPICS) archiver appliance, how we
secure operation, the type of stored contents in the archiver, the process of
monitoring the incoming stream of information, and the use of the archived
information.

##  II Hardwares and Backend Software

###  II-A Network configuration

For each subdetector system, we have dedicated readout system which resides in
the Electronic hut (E-hut), located next to the detector. Each subdetector has
up to ten readout PCs, Each readout PC collects data from COPPERs through
dedicated network connections, and also controls COPPERs. Readout PCs also
collect status of COPPERs and FEEs whose information is collected by COPPERs
through Belle2link. Belle II DAQ network is accessible only inside the Belle
II experimental hall. Belle II DAQ network consists of two parallel networks.
One is dedicated for slow control system and the other is various purposes
including system services, interactive operations and file transfer. Our EPICS
and NSM networks reside inside Belle II DAQ networks. KEK computing cluster
(KEKCC) can be accessed using a dedicated tunnel from DAQ networks as shown in
Fig. 1.

Figure 1: Belle II DAQ network

###  II-B Backend Software

To distribute our monitoring information, we use network shared memory 2
(NSM2)[4] variables and EPICS process variables (PV). Because DAQ slow control
system transfer its information using NSM2, and monitoring system uses CS-
studio which is compatible with EPICS. Network shared memory was developed for
Belle Experiment, and upgraded to NSM2 for Belle II experiments. NSM2
Variables can be transferred using dedicated NSM2 networks inside our DAQ
networks, but our archiver uses EPICS archiver appliance. EPICS archiver
appliance can not receive NSM2 variables. So we created nsm2cad which converts
nsm variables to EPICS PVs. These EPICS PVs can be transferred using EPICS
networks inside our DAQ networks.

###  II-C Archiver

Our archiver is based on EPICS archiver appliance. EPICS archiver appliance is
an implementation of an archiver for EPICS control systems that aims to
archive millions of PVs. Our archiver stores environmental and safety
variables, and subdetector status. We use MySQL that makes database engine
store computed variables and updated regularly in table. We prepared two
identical archiver as shown below.

  * •

CPU : Intel(R) Xeon(R) CPU E3-1230 v6 @ 3.50GHz

  * •

RAM : Kingston 2400MHz 16GB x2

  * •

STS : 250 GB SSD

  * •

MTS : 10 TB HDD

  * •

LTS : 10 TB HDD

The main archiver that stores real-time data, and the other archiver for
backup purpose. PXD and SVD have there own dedicated archiver, for their own
complex data acquisition systems.

##  III Archiver Services

###  III-A Archived information

In the archiver system, we store a large number of variables. For example, the
temperature of various subdetector components, status of water leak sensors,
high voltage power supply status, data acquisition status, and luminosity
information of colliding beams. These variables are collected form subsystems
such as the subdetector readout systems, central logging system, data
acquisition system and the gateway to the SuperKEKB EPICS network. Currently,
approximately 26k PVs are archived as shown in Table. I. Based on our stress
test, The system can stably archived 80k PVs and can archive 100K PVs at
maximum.

TABLE I: Number of archived PVs

Number of PVs PXD 20 have own archiver SVD 354 have own archiver CDC 465 TOP
3065 ARICH 15948 ECL 244 KLM 1023 Trigger 72 ECL Trigger 851 DAQ 210 SuperKEKB
795 etc 9

In our archiver, we store various variables. Most of the subdetector groups
store variables for safe detector operation such as subdetector temperature
water leak status, and humidities. We utilize EPICS PV to monitor in Fig. 2.
SVD group stores hardware occupancy. VXD stores radiation. CDC group stores
high voltage status, FEE status, and gas status. TOP group also stores high
voltage status, gas status, PMT hit rate and FEE status. ARICH group stores
low voltage, high voltage status, FEE status, cooling water temperature,
frontend boards seu status. ECL group stores luminosity information and low-
level details. KLM group stores high voltage status, value of the Data
Concentrator (DC) status registers and resistive plate chamber (RPC) gas
supply status. Trigger(TRG) group stores each step of trigger status. ECLTRG
group stores luminosity information, hitrate, pedestal status, noise,
temperature, trigger bits, and level-1 trigger information. DAQ group stores
HV master status, Run control status, HLT event input rate, TTD status, event
builder (EB) status. From superKEKB side, we store MDI flags, information
about beams and bunches, injection information, Tune parameters, collimator
parameters, pressure, loss monitor and impact point profile.

Figure 2: Safety monitoring system using EPICS PVs

We use short-term storage (STS), mid-term storage (MTS), and long-term storage
(LTS) to store data. STS uses SSD for storage. MTS and LTS use HDD. The data
are stored in the PB (protocol buffers) format. We make use of the archiver to
display information through the CS-studio interface and web browsers for
online monitoring purpose.

###  III-B Archiver Migration and Backup

In our archiver storage, we have STS, MTS, LTS. The data stored in STS are
merged to MTS in 3 days (T1). MTS data are transferred to LTS in a week (T2).
For backup purpose, we have an identical archiver prepared. We synchronize
main archiver and backup archiver every 20 minutes(T3). In case of emergency,
backup archiver performs same operations as main archiver as shown Fig. 3.

Figure 3: Data transfer and synchronization inside archiver system

###  III-C Offline use of archived data

EPICS archiver appliance provides retrieval webapp and supports offline
download. Through retrieval webapp, we can easily check status of the PVs.
Offline download is one of the easiest way to access the archiver data to use
in a batch process. However, the function only supports archiver specific
format called PB, which is not analysis friendly. Moreover, these data can
only be accessible in Belle II DAQ network. We developed a chain of conversion
programs to convert the PB data into the ROOT[3] format by combining existing
tools. As archiver data are available only inside the closed data-acquisition
network which is not accessible from offline computers, we make a daily
conversion and file transfer to the offline computing system at the KEK
(KEKCC). First we convert PB to JSON (JavaScript Object Notation) format using
function of EPICS archiver appliance, and we convert JSON to CSV using a java
program. Then we convert CSV file to ROOT format which is the data format
adopted by the Belle II analysis software framework as shown in Fig. 4. We
transfer these converted ROOT files to KEKCC.

Figure 4: Daily PB to ROOT conversion procedure

We convert our monthly PB file in LTS and transfer it to KEKCC.

##  IV Managing archived variables list

As our detector have many variables, we need to check the status of the
variables, such as connectivity, consistency and list of variables for each
subdetectors. To check connectivity we made short shell and python scripts
which makes a list of disconnected variables. Every morning, archiver experts
receive a list of disconnected PVs in an e-mail from the archiver. Archiver
experts then notify the subdetector experts about the disconnected PVs. We
also have PV list management. As a part of the collaborative service of Belle
II, we use a wiki system of Atlassian Confluence. We provide wiki page of a
list of archived PVs. A confluence wiki page is usually designed for human
readers, but we keep a certain format to be able to parse using python script.
The script compares list of archived PV in archiver and the list on the
confluence page. Based on the output of this script, archiver expert notifies
subdetector experts. This procedure can eventually be automated.

##  V Monitoring Archiver

During the operation, we use online chat system called Rocket.Chat to
communicate among practically everybody who participate in the detector
operation, including the local and remote shifter, subdetector and DAQ
experts, and Belle II commissioning groups. We use Rocket.Chat for fast
notification and e-mail for slow notification.

###  V-A Archiver status

To monitor archiving status, we made a dedicated PV. This PV is updated every
ten seconds, so we can monitor file saving status by checking stored file
information. Our crontab job checks every minute for STS, MTS, LTS. Upon
failure, we will get a e-mail and Rocket.Chat notification. For STS, if the
storage status does not update for more than ten minutes, we will get notified
first, and get additional notification every 2 hours. For MTS, if the storage
status does not update for an hour, we receive notification, and if the
failure sustains we receive further notification every 2 hours. For LTS, if
the storage status does not update for a day, we will receive first
notification. If the failure lasts, we get further notification every 4 hours.

###  V-B Retrieval status

Our retrieval webapp is one of the parts of archiver data distribution system.
We found in some cases, when a flood of data requests exceeds the capability
of the archiver, the retrieval webapp, in Fig. 5, stops responding. In order
to detect such situation, we check every ten minutes whether the retrieval
webapp is working or not by requesting data for past one hour from another PC.
If retrieval webapp does not respond, our alarm system sends an alarm to
Rocket.Chat every ten minutes.

Figure 5: Archived CDC humidity variable distributed using retrieval webapp

###  V-C Fault tolerance

In case of a hardware failure of the archiver, the archiver can be switched to
the backup system simply by manually switching the IP address. In this case,
we might lose up to 20 minutes plus the time for the switching operation of
archived data, since the backup system is synchronized every 20 minutes. The
data files copied to KEKCC can also be served as a backup.

##  VI Summary

To secure stable data taking of archiver system for Belle II detector
operation, we monitor archived variable status, manage archived variables
list, and monitor the archiver itself. With these efforts we can ensure that,
and we would not lose more than 20 minutes of data even in the worst
situation. We are operating our archiver from April, 2019 successfully.

## References

  * [1] T. Abe et al.[Belle-II Collaboration], “Belle II Technical Design Report.“ arXiv:1011.0352 [physics.ins-det]
  * [2] Z.-A. Liu et al., “Belle2Link: An unified high speed data collection with slow control in Belle II experiment.“ in Proc. 18th IEEE-NPSS Real Time Conf., Berkeley, CA, USA, Jun 9-15, 2012.
  * [3] I. Antcheva et al, ”ROOT - A C++ framework for petabyte data storage, statistical analysis and visualization. ”Comp. Phys. Commun., vol. 180, p. 2499, 2009
  * [4] M. Nakao and S. Y. Suzuki, “Network Shared Memory Framework for the Belle Data Acquisition Control System“ IEEE Trans. Nucl. Sci. vol. 47, pp. 267 - 271, 2000.


#  _Gaia_ pulsars and where to find them in EDR3

John Antoniadis Max-Planck-Institut für Radioastronomie, Auf dem Hügel 69,
53121 Bonn, Germany  Argelander-Institut für Astronomie, Universität Bonn, Auf
dem Hügel 71, 53121 Bonn, Germany  Institute of Astrophysics, Foundation for
Research and Technology-Hellas, Voutes, 71110 Heraklion, Greece

###### Abstract

The Early _Gaia_ Data Release 3 (EDR3) provides precise astrometry for nearly
1.5 billion sources across the entire sky. A few tens of these are associated
with neutron stars in the Milky Way and Magellanic Clouds. Here, we report on
a search for EDR3 counterparts to known rotation-powered pulsars using the
method outlined in Antoniadis (2021). A cross-correlation between EDR3 and the
ATNF pulsar catalogue identifies 41 close astrometric pairs ($\lesssim 0\farcs
5$ at the reference epoch of the pulsar position). Twenty six of these are
related to previously-known optical counterparts, while the rest are candidate
pairs that require further follow-up. Highlights include the Crab Pulsar (PSR
B0531+21), for which EDR3 yields a distance of $2.08^{+0.78}_{-0.45}$ kpc (or
$2.00_{-0.38}^{+0.56}$ kpc taking into account the dispersion-measure prior;
errors indicate 95% confidence limits) and PSR 1638$-$4608, a pulsar thus-far
considered to be isolated that lies within 0$\farcs$056 of a _Gaia_ source.

miscellaneous — catalogs — surveys

##  1 Introduction

Most of the $\sim$2900 known pulsars are too faint to be detected at optical
wavelengths (Mignani et al., 2014). However, $\sim 100$ have (sub-)stellar
binary companions bright enough to be studied with space-borne and ground-
based optical telescopes. These systems provide insights into important
physical processes, from stellar evolution and accretion, to the dynamics of
curved spacetime (Wex & Kramer, 2020). In a recent work (Antoniadis, 2021) We
used the second _Gaia_ data release (DR2 Lindegren et al., 2018) to perform a
systematic search for optical counterparts to 1534 rotation-powered pulsars.
This search identified 22 pulsars with previously known counterparts and 8
additional candidate companions to young pulsars. Here we update the results
in Antoniadis (2021) using the recent _Gaia_ EDR3 (Brown et al., 2020;
Lindegren et al., 2020) and Version
1.64111https://www.atnf.csiro.au/research/pulsar/psrcat/; Accessed on December
6, 2020 of the ATNF Pulsar catalogue (PSRCat; Manchester et al., 2005).

##  2 Results

PSRCat v1.64 contains 1670 pulsars with positions known to better than
$0\farcs 5$. As in Antoniadis (2021), potential EDR3 counterparts to these
sources were identified by propagating _Gaia_ astrometric solutions back to
the reference epoch of each pulsar’s position (PosEpoch in PSRCat). As a rule,
sources with angular separations larger than the $2\sigma$ positional error
were discarded. The latter was calculated by taking into account the
positional uncertainties of the pulsar and the corresponding EDR3 source (at
PosEpoch). An error of $0\farcs 25$ was added in quadrature to account for
possible systematic uncertainties, e.g. possible rotations between the
slightly different reference frames and errors due to strong optical
variability (see Antoniadis, 2021, for a more detailed justification).
However, for most positive matches the systematic uncertainties appear to be
smaller.

Table 1 lists all close astrometric pairs with a probability of chance
coincidence smaller than 10%. Given this threshold, the number of false
positives should be $\mathcal{O}(4)$. Most MSPs companions are located between
the main sequence and the WD cooling branch. There appears to be no obvious
correlation between HR position and orbital period (for such a correlation in
cataclysmic variables that occupy the same region see Abril et al., 2020).

###  2.1 Notable sources

  * •

PSR B0531+21 The distance to the Crab Pulsar and its nebula is a long-standing
issue in astronomy (Kaplan et al., 2008). _Gaia_ EDR3 gives a trigonometric
parallax of $\hat{\pi}_{\rm G}=0.51\pm 0.08$ mas for the source. This
translates to a distance of $2.08^{+0.78}_{-0.45}$ kpc (see Antoniadis, 2021,
for details on distance priors). Combining the latter with the distance
estimate derived using the pulsar dispersion measure and the NE2001 model for
the free-electron density in the Galaxy (Cordes & Lazio, 2002), one finds
$2.00_{-0.38}^{+0.56}$ kpc (95% C.L.). This is somewhat smaller than the DR2
distance estimate of $2.55_{-0.62}^{+0.79}$ kpc.

  * •

PSR J1638$-$4608 _Gaia_ 5992089022760118400 was identified as a potential
counterpart to this young pulsar in Antoniadis (2021). However, a full five-
parameter astrometric solution for the source was reported for the first time
in EDR3. With the latter, the concurrent angular separation between the pulsar
and the source becomes $0\farcs 0562\pm 0\farcs 004_{\rm stat.}\pm 0\farcs
2500_{\rm sys}$. This makes a physical association between the two objects
even more likely. The inferred luminosity and color of the source are
consistent with a massive main sequence star. Assuming both sources are at the
same distance ($3.95^{2.55}_{-2.05}$ kpc, taking into account the DM distance
prior), the projected angular separation would be $222^{+143}_{-116}$ AU.
While the timing data for the pulsar do provide evidence for a periodic
modulation (Kerr et al., 2016; Parthasarathy et al., 2019), this is unlikely
to be caused by a massive binary companion.

##  3 Conclusions

Overall, there are only minor differences between DR2 and EDR3. With the
exception of the sources listed in Table 1 most rotation-powered pulsars do
not appear to have an optical counterpart brighter than the _Gaia_ sensitivity
threshold. This implies a binary fraction of young pulsars $f_{\rm young}^{\rm
true}\leq 5.2(8.2)\%$ under the realistic(conservative) assumptions for the
binary properties and current sensitivity thresholds outlined in Antoniadis
(2021).

We recommend further radio timing follow up of the 15 new candidates in Table
1 to investigate their relation with the coincident _Gaia_ sources.

Table 1: Pulsars is _Gaia_ eDR3

Name | $\theta$ | $\sigma_{\rm pos}$ | $\hat{\pi}_{\rm G}$ | $\hat{\pi}_{\rm r}$ | $\mu_{\alpha}$ | $\mu_{\delta}$ | $\mu_{\alpha,r}$ | $\mu_{\delta,r}$ | $P_{s}$ | Pb | DM | $m_{\rm g}$ | Passoc | d | $M_{\rm g}$
---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---
| $\farcs$ | $\farcs$ | mas | mas | mas yr-1 | mas yr-1 | mas yr-1 | mas yr-1 | s | days | mag | pc cm-3 | $m_{\rm g}$ | kpc | mag
J0045$-$7319 | $0.5043$ | $0.2689$ | $-0.04(4)$ | $-$ | $0.58(5)$ | $-1.49(5)$ | $-$ | $-$ | $0.926$ | $51.17$ | $105.4$ | $16.20$ | $0.91$ | $49.97^{+1.13}_{-1.13}$ | $-4.85^{+0.05}_{-0.05}$
J0337+1715 | $0.0081$ | $0.2500$ | $0.54(20)$ | $-$ | $5.48(19)$ | $-4.43(16)$ | $-$ | $-$ | $0.003$ | $1.63$ | $21.3$ | $18.05$ | $1.00$ | $1.69^{+0.62}_{-0.47}$ | $6.59^{+0.68}_{-0.70}$
J0348+0432 | $0.0021$ | $0.2508$ | $-0.04(78)$ | $-$ | $3.44(134)$ | $-0.23(89)$ | $4.04(16)$ | $3.50(60)$ | $0.039$ | $0.10$ | $40.5$ | $20.59$ | $1.00$ | $2.36^{+1.20}_{-1.03}$ | $7.94^{+0.90}_{-1.25}$
J0437$-$4715 | $0.3166$ | $0.2501$ | $7.10(52)$ | $6.37(90)$ | $121.65(57)$ | $-70.70(65)$ | $121.4385(20)$ | $-71.4754(20)$ | $0.006$ | $5.74$ | $2.6$ | $20.35$ | $1.00$ | $0.1570^{+0.0030}_{-0.0040}$ | $14.37^{+0.04}_{-0.06}$
J1012+5307 | $0.0117$ | $0.2500$ | $1.74(29)$ | $0.71(17)$ | $2.74(29)$ | $-25.92(27)$ | $2.61(1)$ | $-25.48(1)$ | $0.005$ | $0.60$ | $9.0$ | $19.59$ | $0.99$ | $1.73^{+1.63}_{-0.58}$ | $8.36^{+1.44}_{-0.89}$
J1023+0038 | $0.0031$ | $0.2500$ | $0.69(7)$ | $0.73(2)$ | $4.61(7)$ | $-17.28(8)$ | $4.76(3)$ | $-17.34(4)$ | $0.002$ | $0.20$ | $14.3$ | $16.23$ | $0.99$ | $1.37^{+0.07}_{-0.07}$ | $5.48^{+0.11}_{-0.11}$
J1024$-$0719 | $0.0753$ | $0.2501$ | $0.86(28)$ | $0.80(30)$ | $-35.46(32)$ | $-48.35(36)$ | $-$ | $-$ | $0.005$ | $-$ | $6.5$ | $19.15$ | $1.00$ | $1.87^{+3.22}_{-0.90}$ | $7.67^{+2.17}_{-1.42}$
J1048+2339 | $0.0087$ | $0.2501$ | $0.49(44)$ | $-$ | $-15.45(35)$ | $-11.62(34)$ | $-18.70$ | $-9.40$ | $0.005$ | $0.25$ | $16.7$ | $19.59$ | $1.00$ | $2.20^{+1.14}_{-0.92}$ | $7.83^{+0.91}_{-1.18}$
J1227$-$4853 | $0.0622$ | $0.2500$ | $0.46(13)$ | $-$ | $-18.77(11)$ | $7.30(90)$ | $-$ | $-$ | $0.002$ | $0.29$ | $43.4$ | $18.07$ | $0.99$ | $2.60^{+2.33}_{-0.92}$ | $5.86^{+1.52}_{-0.99}$
B1259$-$63 | $0.0597$ | $0.2500$ | $0.44(1)$ | $-$ | $-7.090(10)$ | $-0.340(10)$ | $-6.60(18)$ | $-4.40(14)$ | $0.048$ | $1236.72$ | $146.7$ | $9.63$ | $0.96$ | $2.26^{+0.12}_{-0.11}$ | $-6.58^{+0.34}_{-0.32}$
J1311$-$3430 | $0.0116$ | $0.2506$ | $1.93(97)$ | $-$ | $-6.1(16)$ | $-5.14(68)$ | $-$ | $-$ | $0.003$ | $0.07$ | $37.8$ | $20.44$ | $1.00$ | $2.32^{+1.49}_{-1.33}$ | $8.56^{+1.12}_{-1.88}$
J1417$-$4402 | $0.3816$ | $0.2805$ | $0.20(5)$ | $-$ | $-4.76(4)$ | $-5.10(5)$ | $-$ | $-$ | $0.003$ | $5.37$ | $55.0$ | $15.77$ | $0.99$ | $5.06^{+2.50}_{-1.35}$ | $2.02^{+0.98}_{-0.74}$
J1431$-$4715 | $0.0471$ | $0.2500$ | $0.53(13)$ | $-$ | $-11.82(14)$ | $-14.52(15)$ | $-7.0(30)$ | $-8.0(40)$ | $0.002$ | $0.45$ | $59.4$ | $17.73$ | $0.99$ | $2.24^{+1.78}_{-0.72}$ | $5.84^{+1.38}_{-0.89}$
J1723$-$2837 | $0.3120$ | $0.2500$ | $1.07(4)$ | $-$ | $-11.73(4)$ | $-24.05(3)$ | $-$ | $-$ | $0.002$ | $0.62$ | $19.7$ | $15.54$ | $0.93$ | $0.94^{+0.07}_{-0.06}$ | $4.17^{+0.16}_{-0.15}$
J1810+1744 | $0.0592$ | $0.2505$ | $0.65(54)$ | $-$ | $7.54(45)$ | $-4.19(51)$ | $-$ | $-$ | $0.002$ | $0.15$ | $39.7$ | $20.00$ | $0.99$ | $2.42^{+1.38}_{-1.14}$ | $7.61^{+0.98}_{-1.51}$
J1816+4510 | $0.0019$ | $0.2500$ | $0.22(10)$ | $-$ | $-0.06(12)$ | $-4.40(12)$ | $5.30(80)$ | $-3.0(10)$ | $0.003$ | $0.36$ | $38.9$ | $18.20$ | $1.00$ | $4.31^{+2.07}_{-1.44}$ | $4.95^{+0.85}_{-0.88}$
J1957+2516 | $0.0078$ | $0.2505$ | $2.15(85)$ | $-$ | $-4.49(52)$ | $-12.29(101)$ | $-$ | $-$ | $0.004$ | $0.24$ | $44.1$ | $20.28$ | $0.96$ | $2.34^{+1.68}_{-1.48}$ | $5.90^{+2.23}_{-4.14}$
B1957+20 | $0.0889$ | $0.2505$ | $1.2(14)$ | $-$ | $-19.3(13)$ | $-26.6(13)$ | $-16.00(50)$ | $-25.80(60)$ | $0.002$ | $0.38$ | $29.1$ | $20.17$ | $0.96$ | $1.88^{+1.03}_{-0.92}$ | $7.90^{+1.15}_{-1.71}$
J2032+4127 | $0.0476$ | $0.2500$ | $0.57(2)$ | $-$ | $-2.88(2)$ | $-0.95(2)$ | $-$ | $-$ | $0.143$ | $16835.00$ | $114.7$ | $11.28$ | $0.99$ | $1.76^{+0.08}_{-0.08}$ | $-5.11^{+0.11}_{-0.11}$
J2129$-$0429 | $1.3038$ | $0.2500$ | $0.48(7)$ | $-$ | $12.10(7)$ | $10.19(6)$ | $-$ | $-$ | $0.008$ | $0.64$ | $16.9$ | $16.82$ | $1.00$ | $2.18^{+0.74}_{-0.44}$ | $5.05^{+0.63}_{-0.49}$
J2215+5135 | $0.0869$ | $0.2500$ | $0.30(23)$ | $-$ | $0.01(24)$ | $2.24(24)$ | $170.0(220)$ | $82(24)$ | $0.003$ | $0.17$ | $69.2$ | $19.20$ | $0.98$ | $2.99^{+1.49}_{-1.15}$ | $6.37^{+1.12}_{-1.20}$
J2339$-$0533 | $0.1251$ | $0.2504$ | $0.53(18)$ | $-$ | $3.92(20)$ | $-10.28(19)$ | $11.00(4.00)$ | $-29(10)$ | $0.003$ | $0.19$ | $-$ | $18.79$ | $1.00$ | $1.57^{+0.50}_{-0.39}$ | $7.77^{+0.61}_{-0.61}$
Single Pulsars |
B0531+21 | $0.0460$ | $0.2501$ | $0.51(8)$ | $-$ | $-11.51(10)$ | $2.30(6)$ | $-14.70(80)$ | $2.00(80)$ | $0.033$ | $-$ | $56.8$ | $16.53$ | $1.00$ | $2.08^{+0.78}_{-0.45}$ | $3.71^{+0.71}_{-0.54}$
B0540$-$69 | $0.0279$ | $0.2503$ | $0.6(13)$ | $-$ | $3.6(21)$ | $5.0(23)$ | $-$ | $-$ | $0.051$ | $-$ | $146.5$ | $20.77$ | $0.93$ | $62.10^{+1.90}_{-1.90}$ | $-5.84^{+0.07}_{-0.07}$
Small angular separation but most likely not associated |
B1953+29 | $0.1399$ | $0.2500$ | $0.47(17)$ | $-$ | $-3.17(14)$ | $-7.83(17)$ | $-$ | $-$ | $0.006$ | $117.35$ | $104.5$ | $18.70$ | $0.97$ | $3.54^{+3.23}_{-1.70}$ | $3.19^{+1.97}_{-2.28}$
J1435$-$6100 | $0.4139$ | $0.2500$ | $0.42(25)$ | $-$ | $-5.26(22)$ | $-3.23(24)$ | $-$ | $-$ | $0.009$ | $1.35$ | $113.7$ | $18.92$ | $0.95$ | $2.84^{+1.55}_{-1.17}$ | $-1.11^{+5.17}_{-4.33}$
Candidates |
J0534$-$6703 | $0.5187$ | $0.2872$ | $0.16(16)$ | $-$ | $1.27(26)$ | $0.44(19)$ | $-$ | $-$ | $1.818$ | $-$ | $94.7$ | $18.86$ | $0.94$ | $62.10^{+1.90}_{-1.90}$ | $-0.64^{+0.07}_{-0.07}$
J1437$-$6146 | $0.4985$ | $0.2805$ | $0.31(0.03)$ | $-$ | $-5.00(0.03)$ | $-2.95(0.03)$ | $-$ | $-$ | $0.468$ | $-$ | $200.5$ | $15.68$ | $0.90$ | $3.31^{+0.73}_{-0.51}$ | $-0.02^{+1.12}_{-0.84}$
J1509$-$6015 | $0.1999$ | $0.2872$ | $0.19(11)$ | $-$ | $-5.25(11)$ | $-2.39(11)$ | $-$ | $-$ | $0.339$ | $-$ | $423.6$ | $17.76$ | $0.91$ | $4.88^{+4.05}_{-1.96}$ | $0.42^{+4.55}_{-2.68}$
J1542$-$5133 | $0.3258$ | $0.3103$ | $-0.21(27)$ | $-$ | $-2.25(34)$ | $-4.86(28)$ | $-$ | $-$ | $1.784$ | $-$ | $186.0$ | $19.03$ | $0.91$ | $5.37^{+4.91}_{-2.64}$ | $2.81^{+3.76}_{-2.72}$
J1546$-$5302 | $0.5576$ | $0.3094$ | $-$ | $-$ | $-$ | $-$ | $-$ | $-$ | $0.581$ | - | $287.0$ | $21.11$ | $0.97$ | $5.33^{+1.07}_{-1.07}$ | $-5.14^{+2.92}_{-3.01}$
J1614$-$5402 | $0.2811$ | $0.2684$ | $-$ | $-$ | $-$ | $-$ | $-$ | $-$ | $0.573$ | $-$ | $300.0$ | $20.78$ | $0.85$ | $5.83^{+1.17}_{-1.17}$ | $4.64^{+0.86}_{-0.95}$
J1624$-$4411 | $0.2931$ | $0.2513$ | $0.94(49)$ | $-$ | $-3.43(51)$ | $-7.68(36)$ | $-$ | $-$ | $0.233$ | $-$ | $139.4$ | $19.88$ | $0.95$ | $2.75^{+4.54}_{-1.76}$ | $6.23^{+4.54}_{-3.16}$
J1624$-$4721 | $0.3089$ | $0.2744$ | $0.23(98)$ | $-$ | $-3.8(13)$ | $-2.46(77)$ | $-$ | $-$ | $0.449$ | $-$ | $364.0$ | $20.39$ | $0.92$ | $3.72^{+4.84}_{-2.40}$ | $3.53^{+7.04}_{-4.85}$
J1638$-$4608 | $0.0562$ | $0.2504$ | $0.39(52)$ | $-$ | $-4.4(10)$ | $-6.76(84)$ | $-$ | $-$ | $0.278$ | $-$ | $423.1$ | $19.38$ | $0.94$ | $3.65^{+4.74}_{-2.23}$ | $1.98^{+7.76}_{-4.84}$
J1838$-$0549 | $0.5053$ | $0.2536$ | $0.47(0.13)$ | $-$ | $1.64(13)$ | $1.32(12)$ | $-$ | $-$ | $0.235$ | $-$ | $276.6$ | $17.70$ | $0.98$ | $2.54^{+2.25}_{-0.89}$ | $1.18^{+2.44}_{-1.14}$
B1848+12 | $0.3530$ | $0.2503$ | $0.96(1.08)$ | $-$ | $-3.56(1.19)$ | $-7.61(1.25)$ | $-$ | $-$ | $1.205$ | $-$ | $70.6$ | $20.50$ | $0.97$ | $3.43^{+4.83}_{-2.34}$ | $6.06^{+2.00}_{-3.37}$
J1852+0040 | $0.5057$ | $0.2565$ | $2.39(90)$ | - | $-1.00(76)$ | $-4.62(66)$ | $-$ | $-$ | $0.105$ | $-$ | $-$ | $20.21$ | $0.98$ | $2.15^{+4.77}_{-1.65}$ | $4.39^{+4.74}_{-3.95}$
J1903$-$0258 | $0.3872$ | $0.2505$ | $0.61(0.26)$ | $-$ | $-0.59(0.35)$ | $3.78(0.34)$ | $-$ | $-$ | $0.301$ | $-$ | $113.0$ | $18.93$ | $0.96$ | $2.69^{+3.93}_{-1.40}$ | $3.70^{+2.38}_{-4.52}$
J1958+2846 | $0.3890$ | $0.2536$ | $0.38(26)$ | $-$ | $-3.64(22)$ | $-7.26(28)$ | $-$ | $-$ | $0.290$ | $-$ | $-$ | $19.34$ | $0.98$ | $3.57^{+4.38}_{-1.89}$ | $2.82^{+2.76}_{-3.38}$
J2027+4557 | $0.2902$ | $0.2500$ | $0.52(3)$ | - | $2.08(3)$ | $-2.12(3)$ | $-$ | $-$ | $1.100$ | $-$ | $229.6$ | $15.71$ | $0.98$ | $1.94^{+0.18}_{-0.15}$ | $1.64^{+0.28}_{-0.43}$

Note. — see Antoniadis (2021) for details

This research project was partly supported by the Stavros Niarchos Foundation
(SNF) and the Hellenic Foundation for Research and Innovation (H.F.R.I.) under
the 2nd Call of “Science and Society” Action Always strive for excellence –
Theodoros Papazoglou” (Project Number: 72-1/11.8.2020). This work relies on
data from the European Space Agency (ESA) mission _Gaia_
(https://www.cosmos.esa.int/gaia), processed by the _Gaia_ Data Processing and
Analysis Consortium (DPAC,
https://www.cosmos.esa.int/web/gaia/dpac/consortium). This research made use
of NumPy (Harris et al., 2020), Matplotlib (Hunter, 2007) and Astropy
(http://www.astropy.org), a community-developed core Python package for
Astronomy (Astropy Collaboration et al., 2013, 2018) and of NASA’s
Astrophysics Data System Bibliographic Services.

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