GRB 260428A
GCN Circular 44678
Subject
GRB 260428A: TERI Gamma-ray detection
Date
2026-05-21T14:02:09Z (4 months ago)
Edited On
2026-05-21T14:10:24Z (4 months ago)
From
nicholasjkirschner@gmail.com
Edited By
Judith Racusin at NASA/GSFC <judith.racusin@nasa.gov> on behalf of nicholasjkirschner@gmail.com
Via
Web form
Nicholas Kirschner (a), Daniel Shy (b), C.C. Cheung (b), Bernard Phlips (b), Michael Streicher
(c), James Mason (c), Douglas M. Groves (c), Feng Zhang (c), and Willy Kaye (c)
(a) National Research Council Research Associate resident at the U.S. Naval Research
Laboratory, 4555 Overlook Ave SW, Washington, DC 20375
(b) U.S. Naval Research Laboratory, 4555 Overlook Ave SW, Washington, DC 20375
(c) H3D, Inc., 812 Avis Dr., Ann Arbor, MI 48108, USA
The cadmium zinc TElluride Radiation Imager (TERI) gamma-ray telescope [1], operating on
the International Space Station, reports the detection of GRB 260411B, which was also detected
by Fermi GBM (GCN 44415), AstroSat (GCN 44421), GECAM-B (GCN 44423), and
SVOM/GRM (GCN 44424).
Using 1 Hz binning, and adopting T0 = 2026-04-28T14:20:34.992Z, we observe one peak at
T0+1.5s, with peak excess count rate of 49 above the 97 cps baseline rate observed in nearby offsource intervals.
The analysis results presented here are preliminary and currently lack a detailed response
function.
TERI is an Office of Naval Research funded technology demonstrator for large-volume pixelated
CdZnTe detectors developed, built, and operated by the U.S. Naval Research Laboratory (NRL)
in conjunction with H3D, Inc. The pixelated CdZnTe detectors have an energy range of 40 keV
to 3 MeV per pixel. It was launched on 2025 April 21 aboard the Department of Defense Space
Test Program STP-H10 to the ISS. On the ISS, it is located on the SOX external payload facility
on the Columbus module. Analysis of TERI data at NRL is supported by the Office of Naval
Research 6.1.
[1] Shy, Daniel, et al. "Development of the cadmium zinc TElluride Radiation Imager." Journal
of Astronomical Telescopes, Instruments, and Systems 10.4 (2024): 044009-044009
(arXiv:2408.04559).
Distribution Statement A: Approved for public release. Distribution is unlimited.
GCN Circular 44458
Subject
IPN triangulation of GRB 260428A
Date
2026-05-04T15:04:29Z (5 months ago)
From
Anna Ridnaia at Ioffe Institute <ridnaia@mail.ioffe.ru>
Via
Web form
A.S. Kozyrev, D.V. Golovin, M.L. Litvak, I.G. Mitrofanov, and A.B. Sanin
on behalf of the HEND/Mars Odyssey team,
A. Ridnaia, D. Frederiks, A. Lysenko, D. Svinkin,
and T. Cline on behalf of the Konus-Wind team,
A. Goldstein, M. S. Briggs, C. Wilson-Hodge,
and E. Burns on behalf of the Fermi-GBM team,
C. Wang (IHEP), S. Xiong (IHEP), S. Zhang (IHEP),
J. Wei (NAOC), B. Cordier (CEA) on behalf of the SVOM-GRM team,
and
W. Boynton, C. Fellows, K. Harshman, H. Enos, R. Starr,
and A.S. Gardner on on behalf of the GRS-Odyssey GRB team,
report:
The short-duration GRB 260428A
(Fermi-GBM detection: Fermi GBM team, GCN Circ. 44415;
AstroSat-CZTI detection: Goyal et al., GCN Circ. 44421;
GECAM-B detection: Wang et al., GCN Circ. 44423;
SVOM/GRM observation: Wang et al., GCN Circ. 44424)
was detected by Fermi (GBM), Konus-Wind, AstroSat (CZTI),
GECAM-B, SVOM (GRM), and Mars-Odyssey (HEND)
at about 51636 s UT (14:20:36).
We have triangulated it to a preliminary, 3 sigma error box
whose coordinates are:
---------------------------------------------
RA(2000), deg Dec(2000), deg
---------------------------------------------
Center:
283.386 (18h 53m 33s) +0.365 ( +0d 21' 53")
Corners:
283.274 (18h 53m 06s) +1.978 ( +1d 58' 41")
283.221 (18h 52m 53s) +2.065 ( +2d 03' 56")
283.504 (18h 54m 01s) -1.335 ( -1d 20' 06")
283.558 (18h 54m 14s) -1.435 ( -1d 26' 07")
---------------------------------------------
The error box area is 561 sq. arcmin, and its maximum
dimension is 3.5 deg (the minimum one is 3 arcmin).
The Sun distance was 111 deg.
A triangulation map and HEALPix FITS file are posted at
http://www.ioffe.ru/LEA/GRBs/GRB260428_T51639/IPN
The HEALPix triangulation map is the multi-order HEALPix in units of
probability density.
The Konus-Wind time history and spectrum will be given
in a forthcoming GCN Circular.
GCN Circular 44424
Subject
GRB 260428A: SVOM/GRM observation of a possible short burst with extended emission
Date
2026-04-29T15:26:34Z (5 months ago)
From
Chenwei Wang at IHEP <cwwang@ihep.ac.cn>
Via
Web form
SVOM/GRM team: Chen-Wei Wang, Chao Zheng, Zheng-Hang Yu, Shi-Jie Zheng, Yue Huang, Shao-Lin Xiong, Shuang-Nan Zhang (IHEP)
SVOM/ECLAIRs team: Olivier GODET (IRAP)
Report on behalf of the SVOM team:
SVOM/GRM was triggered in-flight by a burst GRB 260428A (SVOM trigger reference: sb26042803) at 2026-04-28T14:20:37.000 UTC (T0), which is also detected by Fermi/GBM (Fermi GBM team, GCN#44415), AstroSat (A. Goyal et al., GCN#44421) and GECAM-B (Wang et al., GCN#44423).
With the event-by-event data downloaded through the X-band ground station, the GRM light curve shows that this burst consists of mutli-pulses hard spikes followed by a soft weak extended emission with a T90 of 4.1 +3.1/-2.1 s in the 15-5000 keV band.
The SVOM/GRM light curve can be found here:
https://www.bursthub.cn//admin/static/svgrb260428A.png
In addition, the position of this burst, as determined by Fermi/GBM (RA = 277.0 deg, Dec = 1.9 deg, Err= 2.1 deg, GCN#44415), is located at about 100 degrees from the SVOM optical axis, which is outside the ECLAIRs field of view.
With this localization, the time-averaged spectrum from T0-1.4 to T0+8.4 s is best fitted by a power law function with an exponential high-energy cutoff. The power law index is -1.11 +0.33/-0.25 and the cutoff energy, parameterized as Epeak, is 1380 +159/-66 keV. The event fluence (10-1000 keV) in this time interval is (4.82 +0.83/-0.79)E-06 erg/cm^2.
GRB 260428A falls into the Type I region in the 'Amati' relation diagram, as shown at:
https://www.bursthub.cn//admin/static/svgrb260428A_amati.png
With the brightness of the prompt emission, the predicted soft X-ray afterglow [1] is shown at:
https://www.bursthub.cn//admin/static/svgrb260428A_xag_pre.png
The Space Variable Objects Monitor (SVOM) is a China-France joint mission led by the Chinese National Space Administration (CNSA, China), National Center for Space Studies (CNES, France) and the Chinese Academy of Sciences (CAS, China), which is dedicated to observing gamma-ray bursts and other transient phenomena in the energetic universe. GRM is developed by the Institute of High Energy Physics (IHEP) of CAS.
The SVOM point of contact for this burst is: Chen-Wei Wang (IHEP)(cwwang@ihep.ac.cn)
[1] Chen-Wei Wang et al. ApJ 997 353 https://doi.org/10.3847/1538-4357/ae2eae
GCN Circular 44423
Subject
GRB 260428A: GECAM-B detection of a possible long duration Type I burst
Date
2026-04-29T15:24:26Z (5 months ago)
From
Chenwei Wang at IHEP <cwwang@ihep.ac.cn>
Via
Web form
Chen-Wei Wang, Shao-Lin Xiong, Chao Zheng, Zheng-Hang Yu (IHEP) report on behalf of GECAM team:
GECAM-B was triggered in-flight by a hard burst GRB 260428A at 2026-04-28T14:20:35.850 UTC (denoted as T0). According to the GECAM-B light curves in about 70-6000 keV, this burst mainly consists of multi-pulses with a duration (T90) of 5.6 +6.8/-2.6 s, which is also detected by Fermi/GBM (Fermi GBM team, GCN#44415), AstroSat (A. Goyal et al., GCN#44421) and SVOM/GRM.
The GECAM-B light curve can be found here:
https://www.bursthub.cn//admin/static/gecambgrb260428A.png
The time-averaged spectrum from T0-0.6 s to T0+4.0 s is best fitted by a power law function with an exponential high-energy cutoff. The power law index is -1.05 +0.24/-0.21 and the cutoff energy, parameterized as Epeak, is 1320 +690/-420 keV. The event fluence (10-1000 keV) in this time interval is (6.02 +0.42/-0.47)E-06 erg/cm^2. Thus GRB 260428A is consistent with Type I GRBs in the 'Amati' relation diagram, as shown at:
https://www.bursthub.cn//admin/static/gecambgrb260428A_amati.png
Gravitational wave high-energy Electromagnetic Counterpart All-sky Monitor (GECAM) mission originally consists of two micro-satellites (GECAM-A and GECAM-B) launched in Dec. 2020. As the third member of GECAM constellation, GECAM-C was launched onboard SATech-01 experimental satellite in July 2022. GECAM mission is funded by the Chinese Academy of Sciences (CAS).
GCN Circular 44421
Subject
GRB 260428A: AstroSat CZTI detection
Date
2026-04-29T10:52:09Z (5 months ago)
From
Anuraag Arya at IIT Bombay <aryaanuraag910@gmail.com>
Via
Web form
A. Goyal (IITB), A. Arya (IITB), M. Tembhurnikar (IUCAA), Harsha K. H. (IUCAA), S. Salunke (IUCAA), G. Waratkar (Caltech/IITB), A. Vibhute (IUCAA), V. Bhalerao (IITB), D. Bhattacharya (Ashoka University/IUCAA), A. R. Rao (IUCAA/TIFR), and S. Vadawale (PRL) report on behalf of the AstroSat CZTI collaboration:
Analysis of AstroSat CZTI data with the CIFT framework (Sharma et al., 2021, JApA, 42, 73) showed the detection of a long GRB 260428A which was also detected by Fermi GBM (Fermi GBM team, GCN Circ. 44415).
The source was clearly detected in the CZT detectors in the 20-200 keV energy range. The light curve peaks at 2026-04-28 14:20:35.79 UTC. The measured peak count rate associated with the burst is 135 (+30, -25) counts/s above the background in the combined data of three quadrants (out of four), with a total of 442 (+143, -149) counts. The local mean background count rate was 207 (+3, -4) counts/s. Using cumulative rates, we measure a T90 of 8.0 (+2.2, -5.7) s.
The source was also clearly detected in the CsI anticoincidence (Veto) detector in the 100-500 keV energy range. The light curve peaks at 2026-04-28 14:20:36.03 UTC. The measured peak count rate associated with the burst is 480 (+68, -72) counts/s above the background in the combined data of all quadrants, with a total of 1659 (+414, -444) counts. The local mean background count rate was 1250 (+10, -10) counts/s. We measure a T90 of 7.6 (+3.3, -3.7) s from the cumulative Veto light curve.
CZTI is built by a TIFR-led consortium of institutes across India, including VSSC, URSC, IUCAA, SAC, and PRL. The Indian Space Research Organisation funded, managed, and facilitated the project.
CZTI data products like interactive and downloadable light curves for this GRB can be found at
https://astrosat.iucaa.in/cift/cift_products/515082033.23/S515082033.23_details.html. CZTI GRB detections are reported regularly on the payload site at: http://astrosat.iucaa.in/czti/?q=grb
GCN Circular 44420
Subject
Fermi GRB 260428A: Global MASTER-Net observations report
Date
2026-04-29T09:48:02Z (5 months ago)
From
Vladimir Lipunov at Moscow State U/Krylov Obs <lipunov@xray.sai.msu.ru>
Via
email
V.Lipunov, E.Gorbovskoy, A.Kuznetsov, K.Zhirkov, I.Panchenko, N.Tiurina, P.Balanutsa, V.Topolev, D.Vlasenko,
G.Antipov, A.Sankovich, Yu.Tselik, Ya.Kechin, V.Senik, A.Chasovnikov, K.Labsina, I. Gorbunov (Lomonosov MSU),
O.Gress, N.Budnev (ISU),
C.Francile, F. Podesta, R.Podesta, E. Gonzalez (Observatorio Astronomico Felix Aguilar (OAFA),
A. Tlatov, D. Dormidontov (Kislovodsk Solar Station of the Pulkovo Observatory),
A.Sosnovskij (CrAO),
A. Gabovich, V.Yurkov (Blagoveschensk Educational StateUniversity),
D.Buckley (SAAO),
R.Rebolo (The Instituto de Astrofisica de Canarias),
L.Carrasco, J.R.Valdes, V.Chavushyan, V.M.Patino Alvarez, J.Martinez,
A.R.Corella, L.H.Rodriguez (INAOE, Guillermo Haro Astrophysics Observatory)
MASTER-OAGH robotic telescope [1] located in Mexico (OAGH National Institute for Astrophysics, Optics and Electronics) started inspect of the Fermi GRB 260428A ( Fermi GBM team, GCN 44415) errorbox 64441 sec after notice time and 64478 sec after trigger time at 2026-04-29 08:15:13 UT, with upper limit up to 19.1 mag. The observations began at zenith distance = 49 deg. The sun altitude is -42.4 deg.
The galactic latitude b = 6 deg., longitude l = 32 deg.
Real time updated cover map and OT discovered available here:
https://master.sai.msu.ru/site/master2/observ.php?id=3278426
We obtain a following upper limits.
Tmid-T0 | Date Time | Site | Coord (J2000) |Filt.| Expt. | Limit| Comment
_________|_____________________|_____________________|____________________________________|_____|_______|_______|________
64508 | 2026-04-29 08:15:13 | MASTER-OAGH | (18h 13m 31.74s , +02d 20m 54.0s) | C | 60 | 16.3 |
64580 | 2026-04-29 08:16:25 | MASTER-OAGH | (18h 21m 26.42s , +02d 19m 39.1s) | C | 60 | 17.1 |
64580 | 2026-04-29 08:16:25 | MASTER-OAGH | (18h 19m 40.92s , +02d 56m 34.7s) | C | 60 | 16.9 |
64723 | 2026-04-29 08:18:49 | MASTER-OAGH | (18h 18m 20.54s , +01d 02m 52.2s) | C | 60 | 18.4 |
64723 | 2026-04-29 08:18:49 | MASTER-OAGH | (18h 20m 05.93s , +00d 25m 55.1s) | C | 60 | 18.5 |
64795 | 2026-04-29 08:20:01 | MASTER-OAGH | (18h 16m 00.39s , +04d 14m 39.8s) | C | 60 | 17.9 |
64866 | 2026-04-29 08:21:11 | MASTER-OAGH | (18h 24m 02.21s , +04d 15m 27.1s) | C | 60 | 17.6 |
64866 | 2026-04-29 08:21:11 | MASTER-OAGH | (18h 22m 16.34s , +04d 52m 23.3s) | C | 60 | 17.4 |
65011 | 2026-04-29 08:23:36 | MASTER-OAGH | (18h 19m 59.66s , -01d 28m 30.2s) | C | 60 | 18.5 |
65011 | 2026-04-29 08:23:36 | MASTER-OAGH | (18h 18m 14.27s , -00d 51m 31.9s) | C | 60 | 18.4 |
65229 | 2026-04-29 08:27:15 | MASTER-OAGH | (18h 13m 26.99s , +02d 20m 32.5s) | C | 60 | 18.1 |
65301 | 2026-04-29 08:28:26 | MASTER-OAGH | (18h 21m 25.52s , +02d 21m 20.4s) | C | 60 | 17.2 |
65301 | 2026-04-29 08:28:26 | MASTER-OAGH | (18h 19m 39.54s , +02d 58m 17.0s) | C | 60 | 16.9 |
68807 | 2026-04-29 09:26:52 | MASTER-OAGH | (18h 16m 03.50s , +04d 15m 09.9s) | C | 60 | 18.8 |
68879 | 2026-04-29 09:28:04 | MASTER-OAGH | (18h 22m 20.90s , +04d 50m 32.1s) | C | 60 | 18.6 |
68879 | 2026-04-29 09:28:04 | MASTER-OAGH | (18h 24m 10.14s , +04d 13m 50.9s) | C | 60 | 18.9 |
69023 | 2026-04-29 09:30:29 | MASTER-OAGH | (18h 18m 11.84s , -00d 52m 17.0s) | C | 60 | 18.9 |
69024 | 2026-04-29 09:30:29 | MASTER-OAGH | (18h 20m 00.14s , -01d 29m 03.2s) | C | 60 | 19.0 |
69240 | 2026-04-29 09:34:05 | MASTER-OAGH | (18h 13m 34.50s , +02d 20m 44.0s) | C | 60 | 18.9 |
69311 | 2026-04-29 09:35:16 | MASTER-OAGH | (18h 19m 39.03s , +02d 56m 25.6s) | C | 60 | 18.6 |
69311 | 2026-04-29 09:35:16 | MASTER-OAGH | (18h 21m 27.49s , +02d 19m 41.1s) | C | 60 | 18.9 |
69457 | 2026-04-29 09:37:42 | MASTER-OAGH | (18h 18m 23.22s , +01d 02m 26.1s) | C | 60 | 19.0 |
69457 | 2026-04-29 09:37:42 | MASTER-OAGH | (18h 20m 11.48s , +00d 25m 40.2s) | C | 60 | 19.0 |
69530 | 2026-04-29 09:38:55 | MASTER-OAGH | (18h 16m 02.94s , +04d 12m 49.0s) | C | 60 | 19.0 |
69601 | 2026-04-29 09:40:06 | MASTER-OAGH | (18h 22m 22.25s , +04d 49m 23.6s) | C | 60 | 18.8 |
69601 | 2026-04-29 09:40:06 | MASTER-OAGH | (18h 24m 11.05s , +04d 12m 40.8s) | C | 60 | 18.9 |
69747 | 2026-04-29 09:42:32 | MASTER-OAGH | (18h 18m 09.51s , -00d 52m 18.5s) | C | 60 | 19.1 |
69747 | 2026-04-29 09:42:32 | MASTER-OAGH | (18h 19m 57.81s , -01d 29m 04.9s) | C | 60 | 19.1 |
Filter C is a clear (unfiltred) band.
The observation and reduction will continue.
The message may be cited.
[1] - V.M. Lipunov, V.G. Kornilov, E.S. Gorbovskoy, N.A. Tiurina & A.S.Kuznetsov, 2023, Astronomical Robotic Networks and Operative Multichanel Astrophysics, Lomonosov MSU PRESS, 591pp.
http : // www.pereplet.ru/lipunov/625.html
GCN Circular 44415
Subject
GRB 260428A: Fermi GBM Final Real-time Localization
Date
2026-04-28T14:31:09Z (5 months ago)
From
Fermi GBM Team at MSFC/Fermi-GBM <do_not_reply@GIOC.nsstc.nasa.gov>
Via
email
The Fermi GBM team reports the detection of a likely LONG GRB
At 14:20:35 UT on 28 Apr 2026, the Fermi Gamma-ray Burst Monitor (GBM) triggered and located GRB 260428A (trigger 799078840.683444 / 260428598).
The on-ground calculated location, using the Fermi GBM trigger data, is RA = 277.0, Dec = 1.9 (J2000 degrees, equivalent to J2000 18h 27m, 1d 53'), with a statistical uncertainty of 2.1 degrees.
The angle from the Fermi LAT boresight is 88.0 degrees.
The skymap can be found here:
https://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2026/bn260428598/quicklook/glg_skymap_all_bn260428598.png
The HEALPix FITS file, including the estimated localization systematic, can be found here:
https://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2026/bn260428598/quicklook/glg_healpix_all_bn260428598.fit
The GBM light curve can be found here:
https://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2026/bn260428598/quicklook/glg_lc_medres34_bn260428598.gif