GCN 43982: GRB 260307A: CALET Gamma-Ray Burst Monitor detection
2026-03-13T10:45:12.905Z | rev 0
Y. Shimizu (Kanagawa U), A. Yoshida, T. Sakamoto, S. Sugita, Y. Kawakubo (AGU),
K. Yamaoka (Nagoya U), S. Nakahira (JAXA), Y. Asaoka (ICRR), S. Torii,
Y. Akaike, K. Kobayashi (Waseda U), T. Tamura (Kanagawa U),
N. Cannady (GSFC/UMBC), M. L. Cherry (LSU), S. Ricciarini (U of Florence),
P. S. Marrocchesi (U of Siena)
and the CALET collaboration:
The long GRB 260307A (Fermi GBM Final Real-time Localization: Fermi GBM team,
GCN Circ. 43939; Glowbug gamma-ray detection: Cheung et al., GCN Circ. 43950;
GECAM-B observation: Zao et al., GCN Circ. 43961) triggered the CALET Gamma-ray
Burst Monitor (CGBM) at 11:27:56.49 UTC on 7 March 2026
(https://cgbm.calet.jp/cgbm_trigger/flight/1456918069/index.html).
The burst signal was seen by all CGBM detectors.
The burst light curve shows a multi-peaked structure that starts
at T+2.8 sec, peaks at T+5.2 sec, and ends at T+8.0 sec.
The T90 and T50 durations measured by the SGM data are 4.6 +/- 0.5 sec
and 2.0 +/- 0.2 sec (40-1000 keV), respectively.
The ground-processed light curve is available at
https://cgbm.calet.jp/cgbm_trigger/ground/1456918069/
The CALET data used in this analysis are provided by
the Waseda CALET Operation Center located at Waseda University.
GCN 43961: GRB260307A: GECAM-B observation of a burst
2026-03-11T14:52:31.876Z | rev 0
Xue-Yuan Zao, Chen-Wei Wang, Chao Zheng, Shao-Lin Xiong (IHEP) report on behalf of GECAM team:
GECAM-B was triggered on-ground by GRB 260307A, at 2026-03-07T11:27:59.350 UTC, which is also detected by Fermi/GBM (Fermi GBM team, GCN #43939).
According to the GECAM-B light curves in about 70-6000 keV, this burst mainly consists of multiple pulses, with a duration (T90) of 4.5 +1.0/-0.5 s.
The GECAM-B light curve can be found here:
https://www.bursthub.cn//admin/static/gecambgrb260307A.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 43950: GRB 260307A: Glowbug gamma-ray detection
2026-03-09T20:35:59.840Z | rev 0
C.C. Cheung, R. Woolf, M. Kerr, J.E. Grove (NRL), A. Goldstein (USRA), C.A. Wilson-Hodge, D. Kocevski (MSFC), and M.S. Briggs (UAH) report:
The Glowbug gamma-ray telescope [1,2,3], operating on the International Space Station, confirms the detection of GRB 260307A, which was detected by Fermi/GBM (GCN 43939) and CALET (Trigger 1456918069). The burst onset is at 2026-03-07 11:27:59.2 with a burst duration of 5.0s.
The analysis results presented here are preliminary and use a response function that lacks a detailed characterization of the surrounding passive structure of the ISS.
Glowbug is a NASA-funded technology demonstrator for sensitive, low-cost gamma-ray transient telescopes developed, built, and operated by the U.S. Naval Research Laboratory (NRL) with support from the University of Alabama in Huntsville, USRA, and NASA MSFC. It was launched on 2023 March 15 aboard the Department of Defense Space Test Program’s STP-H9 to the ISS and operated until 2024 April when it was put in safe storage on orbit. Glowbug was removed from storage and resumed operation on 2025 September 12.
[1] Grove, J.E. et al. 2020, Proc. Yamada Conf. LXXI, arXiv:2009.11959
[2] Woolf, R.S. et al. 2022, Proc. SPIE, 12181, id. 121811O
[3] Woolf, R.S. et al. 2024, Proc. SPIE, 13151, id. 1315108
Distribution Statement A: Approved for public release. Distribution is unlimited.
GCN 43944: Fermi GRB 260307A: Global MASTER-Net observations report
2026-03-08T03:00:45.000Z | rev 0
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-Kislovodsk robotic telescope [1] located in Russia (Lomonosov MSU, Kislovodsk Solar Station of Pulkovo observatory) started inspect of the Fermi GRB 260307A ( Fermi GBM team, GCN 43939) errorbox 52522 sec after notice time and 52542 sec after trigger time at 2026-03-08 02:03:41 UT, with upper limit up to 17.6 mag. The observations began at zenith distance = 27 deg. The sun altitude is -17.6 deg.
The galactic latitude b = 75 deg., longitude l = 43 deg.
Real time updated cover map and OT discovered available here:
https://master.sai.msu.ru/site/master2/observ.php?id=3173784
We obtain a following upper limits.
Tmid-T0 | Date Time | Site | Coord (J2000) |Filt.| Expt. | Limit| Comment
_________|_____________________|_____________________|____________________________________|_____|_______|_______|________
52573 | 2026-03-08 02:03:41 | MASTER-Kislovodsk | (13h 56m 48.56s , +30d 11m 50.0s) | C | 60 | 17.5 |
52671 | 2026-03-08 02:05:19 | MASTER-Kislovodsk | (13h 55m 18.49s , +28d 17m 01.2s) | C | 60 | 17.3 |
52762 | 2026-03-08 02:06:51 | MASTER-Kislovodsk | (13h 41m 41.44s , +28d 16m 16.9s) | C | 60 | 17.1 |
52862 | 2026-03-08 02:08:30 | MASTER-Kislovodsk | (13h 42m 54.18s , +30d 11m 08.6s) | C | 60 | 17.4 |
53171 | 2026-03-08 02:13:40 | MASTER-Kislovodsk | (13h 54m 42.32s , +26d 22m 26.2s) | C | 60 | 17.4 |
53271 | 2026-03-08 02:15:20 | MASTER-Kislovodsk | (13h 41m 19.11s , +26d 22m 57.5s) | C | 60 | 17.6 |
53368 | 2026-03-08 02:16:57 | MASTER-Kislovodsk | (14h 08m 52.75s , +28d 17m 54.2s) | C | 60 | 17.2 |
53469 | 2026-03-08 02:18:38 | MASTER-Kislovodsk | (14h 09m 29.84s , +28d 17m 50.9s) | C | 60 | 12.1 |
53580 | 2026-03-08 02:20:28 | MASTER-Kislovodsk | (13h 48m 25.23s , +33d 57m 51.7s) | C | 60 | 17.3 |
54177 | 2026-03-08 02:30:26 | MASTER-Kislovodsk | (14h 08m 06.54s , +26d 23m 27.0s) | C | 60 | 17.3 |
54278 | 2026-03-08 02:32:07 | MASTER-Kislovodsk | (14h 13m 24.07s , +32d 04m 29.5s) | C | 60 | 17.4 |
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 43939: GRB 260307A: Fermi GBM Final Localization
2026-03-07T13:08:25.339Z | rev 0
The Fermi GBM team reports the detection of a likely LONG GRB
"At 11:27:59.32 UT on 07 March 2026, the Fermi Gamma-ray Burst Monitor (GBM)
triggered and located GRB 260307A (trigger 794575684/260307478).
The on-ground calculated location, using the Fermi GBM trigger data,
is RA = 209.07, Dec = 29.03 (J2000 degrees, equivalent to J2000 13h 56m, 29d 01'),
with a statistical uncertainty of 2.88 degrees.
The angle from the Fermi LAT boresight is 77 degrees.
The skymap can be found here:
https://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2026/bn260307478/quicklook/glg_skymap_all_bn260307478.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/bn260307478/quicklook/glg_healpix_all_bn260307478.fit
The GBM light curve can be found here:
https://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2026/bn260307478/quicklook/glg_lc_medres34_bn260307478.gif"