J/A+A/709/A12 Swift-BAT 150-month hard X-ray catalog ctps (Imam+, 2026)
Source identification for the Swift-BAT 150-month hard X-ray catalog using
soft X-ray observations
Imam K., Torres-Alba N., Marchesi S., Ajello M., Joffre S., Cox I.,
Pizzetti A., Zhao X., Segreto A., Banerjee A., Pal I., Gianolli V.E.,
Stern D.
<Astron. Astrophys. 709, A12 (2026)>
=2026A&A...709A..12I 2026A&A...709A..12I (SIMBAD/NED BibCode)
ADC_Keywords: Surveys ; Active gal. nuclei ; X-ray sources
Keywords: astronomical databases: miscellaneous - catalogs - galaxies: active -
quasars: supermassive black holes
Abstract:
We present a comprehensive catalog of 251 potential counterparts for
250 unassociated hard X-ray sources detected in the Swift- Burst Alert
Telescope (BAT) 150-month hard X-ray survey. Over 150 months of
observation, BAT has detected 2339 sources in the 15-150keV range.
Among these, 344 do not have a low-energy counterpart. Our study
focuses on the analysis of soft X-ray observations (i.e., at energies
<10keV) spatially overlapping with these Swift-BAT new hard X-ray
sources. Such observations were taken with Chandra, Swift-XRT,
eROSITA, and XMM-Newton. Within the sample of 251 potential
counterparts, 94 (37%) are identified as AGN and 58 (23%) as galaxies.
The rest of the 99 (40%) sources include pulsars, cataclysmic
variables and unclassified soft X-ray (0.5-10keV) counterparts.
Redshift data is available for 139 out of the 251 sources, and its
distribution is in close agreement with the redshift distribution of
previous BAT catalogs. We also present the results of a small optical
spectroscopy campaign of 9 (out of 58) galaxies. The majority of these
turned out to be Seyfert 2 galaxies at a redshift slightly larger than
the median of the BAT AGN sample.
Description:
This catalog presents 251 potential counterparts for 250 previously
unassociated hard X-ray sources detected in the Swift-BAT 150-month
survey in the 15-150 keV band. The counterparts are identified using
soft X-ray observations from Chandra, Swift-XRT, eROSITA, and
XMM-Newton. Among the identified counterparts, 94 are classified as
AGN and 58 as galaxies, while the remaining sources include pulsars,
cataclysmic variables, and unclassified soft X-ray counterparts.
Redshift information is available for 139 sources, and its
distribution is consistent with previous Swift-BAT catalogs. The
catalog also includes the results of optical spectroscopic follow-up
observations for nine previously unclassified sources. The full
scientific analysis and discussion are presented in the paper.
This catalog provides positional, classification, and redshift
information for counterparts to Swift-BAT hard X-ray sources.
Auxiliary tables summarize counterpart types, associations with the
Fermi-LAT 4FGL catalog, optical spectroscopic follow-up results, flag
definitions, and redshift statistics.
File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
catalog.dat 147 345 Swift BAT 150 month catalog (table 2)
table3.dat 47 20 Counterpart types of BAT sources
table5.dat 89 13 Summary of the sources in our sample with a
counterpart in the 4FGL-DR4 catalog
table4.dat 38 3 Mean and Median of redshift distribution
table6.dat 62 9 Summary of the originally unclassified sources
in our sample that were followed-up with
optical spectroscopy
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See also:
J/A+A/524/A64 : The 54-month Palermo BAT-survey catalogue (Cusumano+, 2010)
J/ApJ/829/7 : The third Swift/BAT GRB catalog (past ∼11yrs) (BAT3)
(Lien+, 2016)
J/ApJS/235/4 : The 105-month Swift-BAT all-sky hard X-ray survey (Oh+, 2018)
Byte-by-byte Description of file: catalog.dat
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Bytes Format Units Label Explanations
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1- 12 A12 --- BAT Swift-BAT source name (JHHMM.m+DDMM)
14- 20 F7.3 deg RAdeg Right ascension of the BAT source (J2000)
22- 28 F7.3 deg DEdeg Declination of the BAT source (J2000)
30- 32 F3.1 arcmin R95 BAT positional error radius at 95 percent
confidence
34- 36 A3 --- Flags Flags describing the counterpart
association (1)
38- 44 F7.3 deg RAOdeg Right ascension of the counterpart (J2000)
46- 55 F10.6 deg DEOdeg Declination of the counterpart (J2000)
57- 70 F14.10 deg GLON Galactic longitude of the counterpart
72- 86 F15.11 deg GLAT Galactic latitude of the counterpart
88-134 A47 --- Ctp Adopted name of the identified counterpart
in NED
136-141 A6 --- Type Source classification
143-147 F5.3 --- z ?=- Redshift of the source, when available
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Note (1): Flags as follows:
1 = Counterpart within R95
2 = Counterpart in the range R95-6 arcmin
s = Only one potential counterpart
m = Multiple potential counterparts
eR = Counterpart associated using eROSITA
ua = Unassociated (data available, but no counterpart detected)
uo = Unobserved
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Byte-by-byte Description of file: table3.dat
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Bytes Format Units Label Explanations
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1- 36 A36 --- Type Counterpart classification
38- 40 I3 --- Nsrcbgt10 Number of sources with |b| > 10 deg
42- 43 I2 --- Nsrcblt10 Number of sources with |b| < 10 deg
45- 47 I3 --- Ntotal Total number of sources in the sample
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Byte-by-byte Description of file: table5.dat
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Bytes Format Units Label Explanations
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1- 12 A12 --- Name Swift-BAT source name
14- 39 A26 --- CptBAT Adopted BAT counterpart name
41- 58 A18 --- Assoc4FGL Associated source in the 4FGL-DR4 catalog
60- 81 A22 --- Cpt4FGL Counterpart of the 4FGL source
83- 89 A7 --- Type 4FGL source classification
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Byte-by-byte Description of file: table4.dat
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Bytes Format Units Label Explanations
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1- 14 A14 --- Catalog Name of the catalog (JHHMM.m+DDMM)
16- 20 F5.3 --- zmean Mean redshift computed for the sample
22- 26 F5.3 --- e_zmean Uncertainty on the mean redshift
28- 32 F5.3 --- zmedian Median redshift computed for the sample
34- 38 F5.3 --- e_zmedian Uncertainty on the median redshift
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Byte-by-byte Description of file: table6.dat
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Bytes Format Units Label Explanations
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1- 12 A12 --- Name Swift-BAT source name (JHHMM.m+DDMM)
14- 41 A28 --- Cpt Optical counterpart name
43- 47 A5 --- OptType Optical spectral classification
49- 54 F6.4 --- z Redshift derived from optical spectroscopy
56- 62 A7 --- Inst Spectroscopic instrument used
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Acknowledgements:
K. Imam, kimam(at)g.clemson.edu
(End) Patricia Vannier [CDS] 29-Jan-2026