J/A+A/700/A61 eROSITA DR1 variability catalogue (Boller+, 2025)
The eROSITA DR1 variability catalogue.
Boller T., Salvato M., Buchner J., Freyberg M., Haberl F., Maitra C.,
Schwope A., Robrade J., Rukdee S., Rau A., Grotova I., Waddell S., Ni Q.,
Krumpe M., Georgakakis A., Merloni A., Nandra K.
<Astron. Astrophys. 700, A61 (2025)>
=2025A&A...700A..61B 2025A&A...700A..61B (SIMBAD/NED BibCode)
ADC_Keywords: Surveys ; X-ray sources
Keywords: methods: data analysis - catalogs - surveys
Abstract:
With its first All-Sky Survey (eRASS1), the extended ROentgen Survey
with an Imaging Telescope Array (eROSITA) on board the
Spectrum-Roentgen-Gamma (SRG) mission has offered an unprecedented,
comprehensive view of the variable X-ray sky. Featuring enhanced
sensitivity, broader energy coverage, and improved resolution compared
to prior surveys, the eRASS1 Data Release 1 (DR1) catalogue underwent
a variability analysis, focusing on a substantial subset of 128669
sources, all exhibiting a net count exceeding 10. We performed
multiple variability tests, utilising conventional normalised excess
variance (NEV), maximum amplitude variability (AMP), and Bayesian
excess variance methods (bexvar). The analysis focused on binned light
curves, specifically employing one eroday (a great circle scan with a
duration of 4 hours) binning of the German part of the first eROSITA
all-sky survey (eROSITA-DE) data. i.e. the source sample covers only
half of the sky. Within the 128,669 DR1 sources with light curves, our
research pinpointed 808 light curves which show hints of variability
according to the AMP test, and 298 according to the NEV test. However,
after applying suitable thresholds, 90 (123) sources are significantly
variable according to the AMP (NEV) tests. In addition, 1342 sources
are considered variable according to the Bayesian test bexvar, the
total number of unique sources is 1709, forming the catalogue of
variable sources released with this paper. We cross-matched with
existing X-ray catalogues and identified 258, 318, 598, and 120
sources in 4XMM DR13, 2SXPS, 2RXS, and CSC2.1, respectively. Only 27
sources overlap across all catalogues, while 882 are new X-ray
detections from eROSITA DR1. About 70 per cent are coronal stars, 5
per cent QSOs, and 1.6 per cent are normal galaxies. We further
subclassified 18 sources as LMXBs, 11 as HMXBs, and 14 as bright
stars. In this paper, we analyse the variability of eRASS1 sources on
a time scale of only a few days. To study the physics of variable
sources, we need more deeply pointed observations with other X-ray
missions or at least the final depth of the eRASS:8 observations. The
time scale of the eRASS1 observations is not representative of the
time scales of the expected upcoming eRASS catalogues. A substantial
52 per cent of the eRASS1 variable sources were first discovered with
eROSITA. The DR1 variability catalogue is excellent for follow-up
observations with telescopes like XMM-Newton, Chandra, or Swift.
Description:
We examine the variability tests applied to the eROSITA DR1 point
sources. We employ three distinct methods for detecting and
characterising variability. These methods are the normalised excess
variance (NEV), maximum amplitude variability (AMP), and Bayesian
excess variance (Buchner et al., 2022A&A...661A..18B 2022A&A...661A..18B).
File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
varcat.dat 1157 1708 eROSITA DR1 variability catalogue (table A1)
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See also:
J/A+A/682/A34 : SRG/eROSITA all-sky survey catalogs (eRASS1) (Merloni+, 2025)
B/cb : Cataclysmic Binaries, LMXBs, and related objects
(Ritter+, 2004)
I/355 : Gaia DR3 Part 1. Main source (Gaia Collaboration, 2022)
VII/258 : Quasars and Active Galactic Nuclei (13th Ed.)
(Veron-Cetty+ 2010)
IX/69 : XMM-Newton Serendipitous Source Catalogue 4XMM-DR13
(Webb+, 2023)
IX/58 : 2SXPS Swift X-ray telescope point source catalogue
(Evans+, 2020)
IX/70 : Chandra Source Catalog Release 2 (CSC 2.1) (Evans+, 2024)
J/A+A/588/A103 : Second ROSAT all-sky survey (2RXS) source catalog
(Boller+, 2016)
J/A+A/684/A121 : SRG/eROSITA all-sky survey coronal content (Freund+, 2024)
Byte-by-byte Description of file: varcat.dat
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Bytes Format Units Label Explanations
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1- 23 A23 --- IAUName String containing the official IAU name
of the source (IAUNAME)
25- 56 A32 --- DetUId String unique detection ID (DETUID)
58- 63 I6 --- SkyTile Sky tile ID (SKYTILE)
65- 67 I3 --- IdSrc Source ID in each sky tile (ID_SRC)
69- 80 I12 --- UId Integer unique detection (UID)
82- 94 I13 --- UIdHard ?=0 Hard catalog UID of the source with a
strong association, or -UID if the
association is weak (UID_Hard)
96- 98 I3 --- IdCluster Group ID of simultaneously fitted sources
(ID_CLUSTER)
100- 119 F20.16 deg RAdeg Right ascension (ICRS), corrected (RA)
121- 142 F22.18 deg DEdeg Declination (ICRS), corrected (DEC)
144- 158 E15.7 arcsec e_RAdeg ?=- 1 sigma lower error of RA (RA_LOWERR)
160- 171 F12.9 arcsec E_RAdeg ?=- 1 sigma upper error of RA (RA_UPERR)
173- 184 F12.9 arcsec e_DEdeg ?=- 1 sigma lower error of DEC
(DEC_LOWERR)
186- 201 E16.8 arcsec E_DEdeg ?=- 1 sigma upper error of DEC
(DEC_UPERR)
203- 213 F11.8 arcsec posErr 1 sigma position uncertainty (POS_ERR)
215- 225 F11.8 arcsec RADEErr Combined positional error, raw output
from PSF fitting (RADEC_ERR)
227- 244 F18.14 deg GLON Galactic longitude (LII)
246- 267 F22.18 deg GLAT Galactic latitude (BII)
269- 288 F20.16 deg ELON Ecliptic longitude (ELON)
290- 310 F21.17 deg ELAT Ecliptic latitude (ELAT)
312- 320 F9.3 d MJD Modified Julian Date of the observation
(MJD)
322- 330 F9.3 d b_MJD Modified Julian Date of the first
observation of a source (MJD_MIN)
332- 340 F9.3 d B_MJD Modified Julian Date of the last
observation of a source (MJD_MAX)
342- 354 F13.7 --- EXTLike Extent likelihood (EXT_LIKE)
356- 369 F14.6 --- DetLike0 Detection likelihood (DETLIKE0)
371- 384 F14.9 ct MLcts1 Source count rate in the 0.2 -2.3 KeV
(MLRATE1)
386- 398 F13.9 ct s_MLcts1 ?=- 1sigma combined count rate error in
the 0.2 -2.3 KeV (MLRATEERR_1)
400- 412 F13.9 ct e_MLcts1 ?=- 1 sigma lower count rate error in
the 0.2 -2.3 KeV (MLRATELOWERR_1)
414- 425 F12.9 ct E_MLcts1 ?=- 1 sigma lower count rate error in
the 0.2 -2.3 KeV (MLRATEUPERR_1)
427- 440 E14.8 mW/m2 MLFlux1 Source flux in the 0.2 -2.3 KeV
(MLFLUX1)
442- 455 E14.8 mW/m2 s_MLFlux1 ?=- 1 sigma combined flux error in
the 0.2 -2.3 KeV (MLFLUXERR_1)
457- 470 E14.8 mW/m2 e_MLFlux1 ?=- 1 sigma lower flux error in
the 0.2 -2.3 KeV (MLFLUXLOWERR_1)
472- 485 E14.8 mW/m2 E_MLFlux1 ?=- 1 sigma upper flux error in
the 0.2 -2.3 KeV (MLFLUXUPERR_1)
487 I1 --- FSPSNR Source may lie within an overdense region
near a supernova remnant (FLAGSPSNR)
489 I1 --- FSPBPS Source may lie within an overdense
region near a bright point source
(FLAGSPBPS)
491 I1 --- FSPSCL Source may lie within an overdense region
near a stellar cluster (FLAGSPSCL)
493 I1 --- FSPLGA Source may lie within an overdense region
near a local large galaxy (FLAGSPLGA)
495 I1 --- FSPGCCons Source may lie within an overdense region
near a galaxy cluster (FLAGSPGC_CONS)
497 I1 --- FNORADEerr Source contained no RADEErr in the
pre-processed version of the catalogue
(FLAGNORADEC_ERR)
499 I1 --- FNOEXTerr Source contained no e_Ext in the
pre-processed version of the catalogue
(FLAGNOEXT_ERR)
501 I1 --- FNOCTSerr Source contained no e_Cts in the
pre-processed version of the catalogue
(FLAGNOCTS_ERR)
503- 505 I3 --- Ndata Number of data points in the light curve
(NDATA)
507- 514 F8.3 --- Amplmax Maximum Amplitude variability
(see Sect. 4.2) (AMPL_max)
516- 522 F7.3 --- e_Amplmax Uncertainty on Maximum Amplitude
Variability (see Sect. 4.2) (eAMPLmax)
524- 529 F6.3 --- q_Amplmax The ratio between Amp and e_Amp
(see Sect. 4.2) (sAMPLmax)
531- 538 F8.3 --- NEV Normalized excess variance
(see Sect. 4.2) (NEV_1)
540- 545 F6.3 --- e_NEV ?=-1 Uncertainty on Normalized excess
variance (see Sect. 4.2) (e_NEV)
547- 552 F6.3 --- q_NEV ?=-1 The ratio between NEV to e_NEV
(see Sect. 4.2) (s_NEV)
554- 572 F19.17 --- Scatt sigma bexvar (see Sect. 4.2) (SCATT)
574- 592 F19.17 --- b_Scatt lower 10% quantile of sigma bexvar
(see Sect. 4.2) (SCATT_LO)
594- 612 F19.17 --- B_Scatt higher 10% quantile of sigma bexvar
(see Sect. 4.2) (SCATT_HI)
614- 628 I15 --- 4XMM ?=- Corresponding ID in the 4XMM
catalogue (4XMM_SourceID)
630- 639 F10.6 deg RA1deg ?=- Right Ascension (J2000) of the source
in the 4XMM catalogue (4XMM_RAJ2000)
641- 650 F10.6 deg DE1deg ?=- Declination (J2000) of the source in
the 4XMM catalogue (4XMM_DEJ2000)
652- 660 F9.6 arcsec Sepe4XMM ?=- Separation between eROSITA and 4XMM
sources (SepeRO4XMM)
662- 667 I6 --- 2SXPS ?=- Corresponding ID in the 2SXPS
catalogue (2SXPS_SourceID)
669- 677 F9.5 deg RA2deg ?=- Right Ascension of the source in the
2SXPS catalogue (2SXPS_RAJ2000)
679- 687 F9.5 deg DE2deg ?=- Declination of the source in the
2SXPS catalogue (2SXPS_DEJ2000)
689- 697 F9.6 arcsec Sepe2SXPS ?=- Separation between eROSITA and 2SXPS
sources (SepeRO2SXPS)
699- 719 A21 --- 2RXS Corresponding ID (2RXS JHHMMSS.s+DDMMSS)
in the ROSAT/2RXS catalogue
(2RXS_SourceID)
721- 729 F9.5 deg RA3deg ?=- Right Ascension of the source in the
2RXS catalogue (2RXS_RAJ2000)
731- 739 F9.5 deg DE3deg ?=- Declination of the source in the
2RXS catalogue (2RXS_DEJ2000)
741- 749 F9.6 arcsec Sepe2RXS ?=- Separation between eROSITA and 2RXS
sources (SepeRO2RXS)
751- 772 A22 --- CSC2.1 Corresponding ID (2CXO JHHMMSS.s+DDMMSSX)
in the CSC2.1 catalogue
(CSC2p1_SourceID)
774- 788 F15.11 deg RA4deg ?=- Right Ascension of the source in the
CSC2.1 catalogue (CSC2p1_RAJ2000)
790- 804 F15.11 deg DE4deg ?=- Declination of the source in the
CSC2.1 catalogue (CSC2p1_DEJ2000)
806- 814 F9.6 arcsec SepeCSC2.1 ?=- Separation between eROSITA and
CSC2.1 sources (SepeROCSC2p1)
817- 835 I19 --- Hamstar ?=- Corresponding Gaia DR3 in the Hamstar
catalogue (Hamstar_SourceID)
837- 856 F20.16 deg RA5deg ?=- Right Ascension of the Hamstar source
in the Gaia DR3 catalogue
(HGDR3_RAJ2000)
858- 879 F22.18 deg DE5deg ?=- Declination of the Hamstar source in
the Gaia DR3 catalogue (HGDR3_DEJ2000)
881- 891 F11.9 arcsec SepeHamst ?=- Separation between eROSITA and
Hamstar sources (SepEROHamstar)
894- 912 I19 --- GaiaDR3 ?=- Corresponding ID from Salvato et al.
2025 in Gaia DR3 catalogue
(GDR3_sourceID)
914- 933 F20.16 deg RA6deg ?=- Right Ascension of the source in the
Gaia DR3 catalogue (GDR3_RA)
935- 956 F22.18 deg DE6deg ?=- Declination of the source in the
Gaia DR3 catalogue (GDR3_DEC)
958- 969 F12.9 arcsec SepeGDR3 ?=- Separation between eROSITA and
GaiaDR3 sources (SepeROGDR3)
971- 979 A9 --- BSC5 Corresponding ID in the BSC5 catalogue
(BSC5_SourceID)
981- 982 I2 h RA7h ? Right Ascension of the source in the
BSC5 catalogue (BSC5_RAJ2000)
984- 985 I2 min RA7m ? Right Ascension of the source in the
BSC5 catalogue (BSC5_RAJ2000)
987- 990 F4.1 s RA7s ? Right Ascension of the source in the
BSC5 catalogue (BSC5_RAJ2000)
992 A1 --- DE7- Declination sign of the source in the
BSC5 catalogue (BSC5_DEJ2000)
993- 994 I2 deg DE7d ? Declination of the source in the BSC5
catalogue (BSC5_DEJ2000)
996- 997 I2 arcmin DE7m ? Declination of the source in the BSC5
catalogue (BSC5_DEJ2000)
999-1000 I2 arcsec DE7s ? Declination of the source in the BSC5
catalogue (BSC5_DEJ2000)
1002-1009 F8.6 arcsec SepGBSC5 ?=- Separation between Gaia DR3 and BSC5
sources (SepGDR3BSC5)
1011-1026 A16 --- VV Corresponding ID in the Veron & Veron
(VV) catalogue (VV_SourceID)
1028-1029 I2 h RA8h ? Right Ascension of the source in the
VV catalogue (VV_RAJ2000)
1031-1032 I2 min RA8m ? Right Ascension of the source in the
VV catalogue (VV_RAJ2000)
1034-1037 F4.1 s RA8s ? Right Ascension of the source in the
VV catalogue (VV_RAJ2000)
1039 A1 --- DE8- ?=- Declination sign of the source in the
VV catalogue (VV_DEJ2000)
1040-1041 I2 deg DE8d ?=- Declination of the source in the
VV catalogue (VV_DEJ2000)
1043-1044 I2 arcmin DE8m ?=- Declination of the source in the
VV catalogue (VV_DEJ2000)
1046-1047 I2 arcsec DE8s ?=- Declination of the source in the
VV catalogue (VV_DEJ2000)
1049-1056 F8.6 arcsec SepGVV ?=- Separation between Gaia DR3 and
VV source (SepGDR3VV)
1058-1065 A8 --- LMXB Corresponding ID in the LMXB catalogue
(LMXB_SourceID)
1067-1068 I2 h RA9h ? Right Ascension of the source in the
LMXB catalogue (LMXB_RAJ2000)
1070-1071 I2 min RA9m ? Right Ascension of the source in the
LMXB catalogue (LMXB_RAJ2000)
1073-1078 F6.3 s RA9s ? Right Ascension of the source in the
LMXB catalogue (LMXB_RAJ2000)
1080 A1 --- DE9- Declination sign of the source in the
LMXB catalogue (LMXB_DEJ2000)
1081-1082 I2 deg DE9d ? Declination of the source in the LMXB
catalogue (LMXB_DEJ2000)
1084-1085 I2 arcmin DE9m ? Declination of the source in the LMXB
catalogue (LMXB_DEJ2000)
1087-1091 F5.2 arcsec DE9s ? Declination of the source in the LMXB
catalogue (LMXB_DEJ2000)
1093-1101 F9.6 arcsec SepGLMXB ?=- Separation between Gaia DR3 and LMXB
sources (SepGDR3LMXB)
1103-1116 A14 --- HMXB Corresponding ID in the HMXB catalogue
(HMXB_SourceID)
1118-1132 F15.11 deg RA10deg ?=- Right Ascension of the source in the
HMXB catalogue (HMXB_RAJ2000)
1134-1148 F15.11 deg DE10deg ?=- Declination of the source in the
HMXB catalogue (HMXB_DEJ2000)
1150-1157 F8.6 arcsec SepGHMXB ?=- Separation between Gaia DR3 and
HMXB sources (SepGDR3HMXB)
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Acknowledgements:
Thomas Boller, bol(at)mpe.mpg.de
(End) Patricia Vannier [CDS] 19-Jun-2025