J/A+A/707/A382 Second H.E.S.S. GRB catalogue (Acharyya+, 2026)
The Second H.E.S.S. gamma-ray burst catalogue:
15 years of GRB observations with the H.E.S.S. telescopes.
Acharyya A., Aharonian F., Arcaro C., Ashkar H., Backes M.,
Barbosa Martins V., Batzofin R., Becherini Y., Berge D., Bernloehr K.,
Boettcher M., Boisson C., Bolmont J., Borowska J., Brun F., Bruno B.,
Burger-Scheidlin C., Casanova S., Celic J., Cerruti M., Chandra S., Chen A.,
Chernyakova M., Chibueze J.O., Chibueze O., Collins T., Cornejo B.,
Cotter G., Damascene Mbarubucyeye J., Davids I.D., de Assis Scarpin J.,
de Bony de Lavergne M., de Naurois M., de Ona Wilhelmi E.,
Delgado Giler A.G., Devin J., Djannati-Atai A., Djuvsland J., Dmytriiev A.,
Egberts K., Egg K., Ernenwein J.-P., Escanuela Nieves C., Filipovic M.D.,
Fontaine G., Funk S., Gabici S., Gallant Y.A., Genaro M., Glicenstein J.F.,
Glombitza J., Grondin M.-H., Heckmann L., Hess B., Hinton J.A., Hofmann W.,
Holch T.L., Holler M., Horns D., Huang Z., Jamrozy M., Jankowsky F.,
Jaroschewski I., Jung-Richardt I., Kasai E., Kasprzak K., Katarzynski K.,
Kerszberg D., Khelifi B., Kluzniak W., Komin N., Kosack K., Kostunin D.,
Lang R.G., Lazarevic S., Lemoine-Goumard M., Lenain J.-P., Liniewicz P.,
Luashvili A., Mackey J., Malyshev D., Malyshev D., Marandon V., Mayer M.,
Mehta A., Mikhno A., Mitchell A.M.W., Moderski R., Moghadam M.O.,
Mohrmann L., Montanari A., Moulin E., Niemiec J., O'Brien P.,
Olivera-Nieto L., Panny S., Panter M., Parsons R.D., Pensec U., Pichard P.,
Pita S., Puehlhofer G., Punch M., Quirrenbach A., Regeard M., Reimer A.,
Reimer O., Reis I., Ren H., Reville B., Rieger F., Rudak B.,
Ruiz-Velasco E., Sabri K., Sahakian V., Salzmann H., Sanchez D.A.,
Jimeno D., Santangelo A., Sasaki M., Schuessler F., Senniappan M.,
Shapopi J.N.S., Si Said W., Sol H., Spencer S., Stawarz L., Steinmassl S.,
Tanaka T., Taylor A.M., Taylor G.L., Terrier R., Tsirou M., Unbehaun T..,
van Eldik C., Vecchi M., Venter C., Vink J., Wach T., Wagner S.J.,
Wierzcholska A., Zacharias M., Zdziarski A.A., Zhong W., Zhu S.J., Zech A.
<Astron. Astrophys. 707, A382 (2026)>
=2026A&A...707A.382A 2026A&A...707A.382A (SIMBAD/NED BibCode)
ADC_Keywords: Gamma rays
Keywords: radiation mechanisms: non-thermal - gamma-ray burst: general -
gamma-rays: general
Abstract:
Recent observational efforts using imaging atmospheric Cherenkov
telescopes (IACTs) have led to firm detections of very-high-energy
(VHE) signals from bright gamma-ray bursts (GRBs), often at moderate
redshifts.
This work presents 15 years of H.E.S.S. GRB observations and examines
their implications through population comparisons and selected
modelling cases.
GRBs are a key science target of the High Energy Stereoscopic System
(H.E.S.S.). With a low-energy threshold (≲100GeV) and rapid
repointing capabilities, H.E.S.S. can begin follow-up observations
within tens of seconds after a GRB trigger, covering the late prompt
or early afterglow phases.
We report GRB follow-up observations with H.E.S.S. from 2004 to 2019,
which resulted in no significant VHE signals (aside from the
detections of GRB 180720B and GRB 190829A). The resulting upper limits
comprise the largest set available for GRBs at VHE.
A subset of bursts with favourable conditions were selected for X-ray
analysis and emission modelling. Population studies were performed to
compare detected and non-detected GRBs. The results indicate that
VHE-detected GRBs are not a distinct population, but tend to feature
luminous X-ray emission and favourable redshift and observing
conditions. This highlights the potential of next-generation IACTs
such as the Cherenkov Telescope Array Observatory (CTAO), whose lower
energy threshold will enhance the detection of fainter and more
distant GRBs.
Description:
We report on the analysis of 89 gamma-ray bursts (GRBs) observed by
the High Energy Stereoscopic System (H.E.S.S.) from 2004 to 2019. Two
of these, GRB 180720B and GRB 190829A, were detected in the
very-high-energy (VHE, E>100GeV) gamma-ray band. No significant VHE
emission was found from the other 87 GRBs. We present the VHE upper
limits (ULs) for the well-localized GRBs (uncertainty <0.2deg) and
UL maps for the poorly localized ones. We present a population study
of the observed GRBs and detailed modelling of three specific GRBs
(GRB 100621A, GRB 131030A, and GRB 161001A).
The tables presented here were derived from the analysis of 15 years
of H.E.S.S. data.
Table 1 contains modelling parameters definition and results for the
three selected GRBs.
Table 2 contains p-value from the KS test of the Swift/BAT
parameters.
Table 3 contains p-value from the KS test performed to compare the
distribution of the parameters measured by Fermi/GBM.
Table 4 contains p-value from the KS test of the Swift/XRT light curve
parameters.
Table A.1 shows the GRB population after different selection and
analysis stages.
Table A.2 lists the H.E.S.S. follow-up observations triggered by
Fermi/GBM.
Table A.3 contains multi-wavelength information for the H.E.S.S. GRB
sample from GCN Circulars.
Table A.4 provides the analysis results and upper limits for the
well-localized GRB sample.
File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
table1.dat 83 9 Modelling parameters and results
table2.dat 88 4 KS test p-values (Swift/BAT)
table3.dat 88 4 KS test p-values (Fermi/GBM)
table4.dat 88 10 KS test p-values (Swift/XRT)
tablea1.dat 46 4 GRB population selection stages
tablea2.dat 57 16 H.E.S.S. follow-up observations (Fermi/GBM)
tablea3.dat 65 63 Multi-wavelength information from GCN Circulars
tablea4.dat 102 59 GRB analysis results
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Byte-by-byte Description of file: table1.dat
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Bytes Format Units Label Explanations
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1- 45 A45 --- Param Parameter description
48- 57 A10 --- GRB10 GRB 100621A Value
61- 71 A11 --- GRB13 GRB 131030A Value
75- 83 A9 --- GRB16 GRB 161001A Value
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Byte-by-byte Description of file: table2.dat table3.dat table4.dat
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Bytes Format Units Label Explanations
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1- 28 A28 --- Param Parameter description
30- 45 A16 --- PvalObs p-value observed vs Whole population
48- 67 A20 --- PvalDet p-value detected at VHE vs Whole
69- 88 A20 --- PvalX19 p-value detected (except GRB 190829A)
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Byte-by-byte Description of file: tablea1.dat
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Bytes Format Units Label Explanations
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1- 33 A33 --- Stage Selection stage
35- 37 I3 --- Nloc ?=0 Number of loc GRBs (0 if N/A)
39- 41 I3 --- Nunloc ?=0 Number of un-loc GRBs (0 if N/A)
43- 46 I4 --- Total Total number
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Byte-by-byte Description of file: tablea2.dat
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Bytes Format Units Label Explanations
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1- 14 A14 --- Name GRB Name (Fermi/GBM ID)
16- 35 A20 "datime" T0 Burst onset time (UTC)
37- 43 F7.1 min Delay Observation delay
45- 57 A13 --- Config Analysis configuration
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Byte-by-byte Description of file: tablea3.dat
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Bytes Format Units Label Explanations
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1- 11 A11 --- Name GRB Name
12- 13 A2 --- n_Name [p#* ] Note on Name (1)
15- 23 A9 --- Inst Trigger Instrument
26- 27 I2 h RAh Right Ascension (J2000)
29- 30 I2 min RAm Right Ascension (J2000)
32- 33 I2 s RAs Right Ascension (J2000)
35 A1 --- DE- Declination sign (J2000)
36- 37 I2 deg DEd Declination (J2000)
39- 40 I2 arcmin DEm Declination (J2000)
42- 43 I2 arcsec DEs Declination (J2000)
45- 50 F6.2 arcmin ePos Localization uncertainty
52 A1 --- l_T90 [~> ] Limit flag on T90
53- 57 F5.1 s T90 Burst duration (T90)
59 A1 --- Radio [YN-] Radio detection
62 A1 --- Opt [YN-] Optical detection
65 A1 --- HE [YN-] High-Energy gamma-ray detection
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Note (1): Note as follows:
p = Naming convention note. GRB 041211B uses suffix "B" to distinguish
it from GRB 041211A, which occurred earlier on the same day
* = These GRBs do not appear with a GCN-style name in the literature;
auto-generated name from GCNweb
(https://user-web.icecube.wisc.edu/~grbweb_public/index.html)
# = GRBs detected by Fermi/GBM; not included in Table A.4
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Byte-by-byte Description of file: tablea4.dat
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Bytes Format Units Label Explanations
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1- 12 A12 --- Name GRB Name
14- 33 A20 --- T0 Burst onset time (UTC)
35- 41 F7.1 min Delay Observation delay
43- 46 F4.1 h Exp Exposure time
48- 60 A13 --- Config Analysis configuration (e.g. stereo loose)
62- 65 I4 --- Non Number of ON events
67- 71 I5 --- Noff Number of OFF events
73- 78 F6.2 --- Alpha Acceptance-weighted exposure ratio
80- 85 F6.2 --- Signi Significance (in sigma)
87- 90 I4 GeV Eth Energy threshold
92- 96 F5.1 10-12/cm2/s Flux1UL Flux UL (alpha=-2.5) in 10^-12 cm^-2 s^-1
98-102 F5.1 10-12/cm2/s Flux2UL Flux UL (alpha=-5.0) in 10^-12 cm^-2 s^-1
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Acknowledgements:
From A. Acharyya, edna.ruve(at)gmail.com
We acknowledge support from the agencies and organizations under
Funding Agencies at http://www.mpi-hd.mpg.de/hfm/HESS/pages/credits.
(End) A. Acharyya [H.E.S.S. Collaboration], Patricia Vannier [CDS] 21-Jan-2026