J/A+A/697/A50 EXOD (XMM-Newton X-ray Outburst Detector) catalogue (Khan+, 2025)
The EXOD search for faint transients in XMM-Newton observations. Part II.
Khan N., Quintin E., Webb N.A., Webbe R., Gupta M., Pastor-Marazuela I.,
Castellani F., Schwope A.D., Traulsen I., Nebot A.
<Astron. Astrophys. 697, A50 (2025)>
=2025A&A...697A..50K 2025A&A...697A..50K (SIMBAD/NED BibCode)
ADC_Keywords: X-ray sources ; Transient
Keywords: instrumentation: detectors - techniques: image processing -
X-rays: general
Abstract:
The XMM-Newton observatory has accumulated a vast archive of over
17000 X-ray observations over the last 25 years. However, the standard
data processing pipelines may fail to detect certain types of
transient X-ray sources, due to their short-lived or dim nature.
Identifying these transient sources is important for understanding the
full range of temporal X-ray behaviour, as well as understanding the
types of sources that could be routinely detected by future missions
such as Athena.
The aim of this work is to reprocess XMM-Newton archival observations
using newly developed dedicated software in order to identify
neglected and missed transient X-ray sources that were not detected by
the existing pipeline.
We used a new approach that builds upon previous methodologies, by
transforming event lists into data cubes, which are then searched for
transient variability in short time windows. Our method enhances the
detection capabilities in the Poisson regime by accounting for the
statistical properties of sparse count rates, and allowing the search
for transients in previously discarded periods of high background
activity.
Our reprocessing efforts identified 32247 variable sources at the
three-sigma level and 4083 sources at the five-sigma level in 12926
XMM archival observations. We highlight four noteworthy sources: a
candidate quasi-periodic eruption (QPE), a new magnetar candidate, a
previously undetected Galactic hard X-ray burst, and a possible X-ray
counterpart to a Galactic radio pulsar.
Our method demonstrates a new, fast, and effective way to process
event list data from XMM-Newton, which is efficient in finding rapid
outburst-like or eclipsing behaviour. This technique can be adapted
for use with future telescopes, such as Athena, and can be generalised
to other photon counting instruments operating in the low-count
Poisson regime.
Description:
The EXOD (XMM-Newton X-ray Outburst Detector) catalogue is a
collection of rapid X-ray transient detections identified in photon
counting data from the XMM-Newton observatory. The catalogue spans
15105 XMM-Newton observations from 2001-08-19 to 2023-11-16.
EXOD identifies transient X-ray outbursts by analyzing photon event
data with multiple time binnings (5s, 50s, 200s) across three energy
bands: soft (0.2-2.0keV), hard (2.0-12.0keV), and full (0.2-12.0keV).
The catalogue provides a valuable resource for studying variable and
transient X-ray sources, including magnetars and other high-energy
astrophysical phenomena.
File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
exoddr1.dat 400 60127 EXOD detection catalogue
exoddr1u.dat 632 32247 EXOD source catalogue
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See also:
II/378 : XMM-OM Serendipitous Source Survey Catalogue (XMM-SUSS6.0)
(Page+, 2023)
IX/69 : XMM-Newton Serendipitous Source Catalogue 4XMM-DR13 (Webb+, 2023)
I/355 : Gaia DR3 Part 1. Main source (Gaia Collaboration, 2022)
http://xmmssc.irap.omp.eu/exod : EXOD Homepage
https://github.com/nx1/EXOD2 : EXOD GitHub
Byte-by-byte Description of file: exoddr1.dat
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Bytes Format Units Label Explanations
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1- 29 A29 --- DetId Unique detection ID (detid)
31- 55 A25 --- SrcId IAU Identifier for grouped detections
within 20", EXOD JJJMMSS.ss+DDMMSS.ss
(srcid)
57- 61 I5 --- RegId ID for Unique region in table 2
(uniqueregid)
63- 82 F20.16 deg RAdeg Right ascension of the detection
(J2000) (ra_deg)
84-103 F20.16 deg DEdeg Declination of the detection
(J2000) (dec_deg)
105-123 F19.13 --- X X in projected sky coordinates (X)
125-143 F19.13 --- Y Y in projected sky coordinates (Y)
145-148 I4 --- Areabbox Area of detection and Extraction region
(area_bbox)
152-175 F24.17 ct MeanPixInt Mean counts in one image pixel
(meanpixelintensity)
177-181 I5 ct lcnMax Maximum counts in 1 bin of LC (lcnmax)
183-187 I5 ct lcnMin Maximum counts in 1 bin of LC (lcnmin)
189-196 I8 ct lcnSum Summed counts in LC (lcnsum)
198-219 F22.16 ct lcnMean Mean counts in LC (lcnmean)
221-242 F22.16 ct lcnStd std counts in LC (lcnstd)
244-266 E23.16 ct lcnSkew LC skew (lcnskew)
268-290 E23.16 ct lcnKurt LC kurtosis (lcnkurt)
292-313 E22.17 --- lcsigMaxBpeak Maximum sigma equivalent of peak in LC
(lcsigmamaxBpeak)
315-336 E22.17 --- lcsigMaxBecl Maximum Sigma equivalent of eclipse in LC
(lcsigmamaxBeclipse)
338-358 E21.16 --- lcratio-bti Percent of LC that is a bad time interval
(lcratiobti)
360-363 I4 --- lcBinMin Minimum distance used for peak finding
(lcbinminbetweenpeaks)
365-366 I2 --- lcnPeaks Number of peaks found in LC (lcnpeaks)
368-390 E23.17 --- lckspval Kolmogorov Smirnov test calculated
against BG (lckspval)
392 I1 --- fTbin5nl5 [0/1] Flag for lcs with < 5 counts in a
bin (filttbin5nl_5)
394 I1 --- fExclude [0/1] Flag for excluded observation IDs
(filtexcludeobsid)
396 I1 --- f5sig [0/1] Flag for 5 sigma detection
(filt_5sig)
398 I1 --- fg20Det [0/1] Flag for many detections in 1 obsid
(filtg20_detections)
400 I1 --- fHotpix [0/1] Flag for hot pixel regions
(filthotpixel)
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Byte-by-byte Description of file: exoddr1u.dat
--------------------------------------------------------------------------------
Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1- 5 I5 --- RegId Unique Region Number (region_num)
7- 31 A25 --- SrcId IAU Identifier for grouped detections
within 20", EXOD JHHMMSS.ss+DDMMSS.ss
(srcid)
33- 52 F20.16 deg RAdeg Right ascension of the detection (J2000)
(ra_deg)
54- 75 F22.18 deg DEdeg Declination of the detection (J2000)
(dec_deg)
77- 79 I3 --- Ndetec Number of times the source was detected
(n_detections)
81-123 A43 --- SimbadId SIMBAD Identifier (simbadmainid)
125-146 A22 --- SimbadType SIMBAD otype (simbadmaintype)
148-162 F15.10 deg RAsdeg ? SIMBAD Right ascension (J2000) (simbad_ra)
164-177 F14.10 deg DEsdeg ? SIMBAD Declination (J2000) (simbad_dec)
179-198 F20.16 arcsec SepS ? SIMBAD separation (simbadSEPARCSEC)
200-227 A28 --- GaiaDR3 Gaia DR3 ID (gaia_DR3Name)
229-244 F16.11 deg RAGdeg ? Gaia Right ascension (J2000) (gaia_RAdeg)
246-260 F15.11 deg DEGdeg ? Gaia Declination (J2000) (gaia_DEdeg)
262-282 F21.16 arcsec SepGaia ? Gaia Separation (gaiaSEPARCSEC)
284-293 F10.6 mag Gmag ? Gaia G Magnitude (gaia_Gmag)
295-304 F10.6 mag BPmag ? Gaia BP Magnitude (gaia_BPmag)
306-315 F10.6 mag RPmag ? Gaia RP Magnitude (gaia_RPmag)
317-327 F11.4 pc DistGaia ? Gaia Distance (gaia_Dist)
329-336 F8.1 K TeffGaia ? Gaia Effective Temperature (gaia_Teff)
338-350 A13 --- VarFlagGaia Gaia Variability Flag (gaia_VarFlag)
352-367 A16 --- SUSS6-XMMOM SUSS6 XMM OM Source name, JHHMMSS.s+DDMMSS
(SUSS6_XMMOM)
370-376 I7 --- SUSS6-ID ? SUSS6 Source number (SUSS6_ID)
380-390 F11.6 deg RASdeg ? SUSS6 Right ascension (J2000)
(SUSS6_RAJ2000)
392-401 F10.6 deg DESdeg ? SUSS6 Declination (J2000) (SUSS6_DEJ2000)
403-422 F20.16 arcsec DistSUSS6 ? SUSS6 Separation (SUSS6SEPARCSEC)
424-426 I3 --- NobsSUSS6 ? SUSS6 Number of observation IDs
(SUSS6_Nobs)
430-438 F9.5 mag UVW2mag ? SUSS6 Source AB magnitude UVW2
(SUSS6_UVW2mAB)
440-447 F8.4 mag UVM2mag ? SUSS6 Source AB magnitude UVM2
(SUSS6_UVM2mAB)
449-456 F8.4 mag UVW1mag ? SUSS6 Source AB magnitude UVW1
(SUSS6_UVW1mAB)
458-465 F8.4 mag Umag ? SUSS6 Source AB magnitude U (SUSS6_UmAB)
467-474 F8.4 mag Bmag ? SUSS6 Source AB magnitude B (SUSS6_BmAB)
476-483 F8.4 mag Vmag ? SUSS6 Source AB magnitude V (SUSS6_VmAB)
485-505 A21 --- XMMName XMM-DR14 IAU Name, 4XMM JHHMMSS.s+HHMMSS
(DR14_IAUNAME)
507-521 I15 --- XMMrcId ?=0 Source identifier in XMM-DR14
(DR14_SRCID)
523-543 F21.16 deg RAXdeg ? Right ascension (J2000) (DR14SCRA)
545-564 F20.16 deg DEXdeg ? Declination (J2000) (DR14SCDEC)
566-585 F20.16 arcsec PoserrXMM ? XMM-DR14 position uncertainty
(DR14SCPOSERR)
587-609 E23.17 mW/m2 Flux8 ? XMM-DR14 Mean flux in 0.2-12keV band
(erg/cm^2%/s) (DR14SCEP8FLUX)
611-630 F20.16 arcsec SepXMM ? XMM-DR14 seperation in arcseconds
(DR14SEPARCSEC)
632 I1 --- VarFlagXMM [0/1] XMM-DR14 Variability Flag
(DR14SCVAR_FLAG)
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Acknowledgements:
N. Khan, norman1000(at)gmail.com
References:
Pastor-Marazuela et al., Paper I 2020A&A...640A.124P 2020A&A...640A.124P
(End) Patricia Vannier [CDS] 26-Mar-2025