GRB 260312B
GCN Circular 44018
Subject
GRID detection of GRB 260312B
Date
2026-03-15T11:40:03Z (7 months ago)
From
GRID Student Team at Tsinghua University <grid@tsinghua.edu.cn>
Via
Web form
Fanqing Zhou, Longhao Li, Chenyu Wang report on behalf of the GRID Collaboration:
GRID-11B reports the detection of the long-duration GRB 260312B, which was also detected by Fermi GBM (GCN Circular 43969), MASTER-Kislovodsk (GCN Circular 43973), BALROG (GCN Circular 43970), Glowbug (GCN Circular 43976), AstroSat CZTI (GCN Circular 43989).
The event was triggered with GRID on 2026-03-12 at 09:46:46 UTC. The measured burst duration (T90) in the 30-2000 keV range is approximately 11.8+/-2.3 seconds.
The GRID light curve of this event can be found at https://mirrors.tuna.tsinghua.edu.cn/GRID/data/GRID-GCN/GRB260312B/GRID_260312B_ltcv.pdf.
GRID is a student-led project to monitor the transient gamma-ray sky with multiple detectors onboard different nanosatellites in the era of multi-messenger astronomy. For more information about GRID, please refer to the following references: https://doi.org/10.1007/s10686-019-09636-w and https://doi.org/10.1007/s10686-021-09819-4.
GCN Circular 43989
Subject
GRB 260312B: AstroSat CZTI detection
Date
2026-03-13T13:07:30Z (7 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 260312B which was also detected by Fermi GBM (Fermi GBM Team , GCN Circ. 43969), and Glowbug (Cheung et. al., GCN Circ. 43976).
The source was clearly detected in the CZT detectors in the 20-200 keV energy range. The light curve peaks at 2026-03-12 09:46:53.50 UTC. The measured peak count rate associated with the burst is 131 (+29, -30) counts/s above the background in the combined data of three quadrants (out of four), with a total of 605 (+164, -182) counts. The local mean background count rate was 186 (+3, -4) counts/s. Using cumulative rates, we measure a T90 of 14 (+1, -6) s.
The source was also faintly detected in the CsI anticoincidence (Veto) detector in the 100-500 keV energy range.
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 GRB detections are reported regularly on the payload site at:
http://astrosat.iucaa.in/czti/?q=grb
GCN Circular 43976
Subject
GRB 260312B: Glowbug gamma-ray detection
Date
2026-03-12T23:50:31Z (7 months ago)
From
C.C. Cheung at Naval Research Lab <Teddy.Cheung@nrl.navy.mil>
Via
Web form
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, reports the detection of GRB 260312B, which was also detected by Fermi/GBM (GCN 43969, 43970).
Using an adaptive window with a resolution of 32-ms, the burst onset is determined to be 2026-03-12 09:46:45.000 with a duration of 12.3 s and a total significance of about 43 sigma. The light curve comprises a faint peak at ~T0+1s and a primary peak at ~T0+7s. Note that data from ~T0+4.0s to +6.0s and ~T0+10.0s to +11.5s suffered from deadtime in various detectors.
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 Circular 43973
Subject
Fermi GRB 260312B: Global MASTER-Net observations report
Date
2026-03-12T16:45:30Z (7 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-Kislovodsk robotic telescope [1] located in Russia (Lomonosov MSU, Kislovodsk Solar Station of Pulkovo observatory) started inspect of the Fermi GRB 260312B ( Fermi GBM team, GCN 43969) errorbox 24262 sec after notice time and 24340 sec after trigger time at 2026-03-12 16:32:26 UT, with upper limit up to 16.8 mag. Observations started at twilight. The observations began at zenith distance = 80 deg. The sun altitude is -15.4 deg.
The galactic latitude b = -63 deg., longitude l = 154 deg.
Real time updated cover map and OT discovered available here:
https://master.sai.msu.ru/site/master2/observ.php?id=3182510
We obtain a following upper limits.
Tmid-T0 | Date Time | Site | Coord (J2000) |Filt.| Expt. | Limit| Comment
_________|_____________________|_____________________|____________________________________|_____|_______|_______|________
24370 | 2026-03-12 16:32:26 | MASTER-Kislovodsk | (01h 43m 41.60s , -02d 12m 39.7s) | C | 60 | 16.1 |
24472 | 2026-03-12 16:34:07 | MASTER-Kislovodsk | (01h 43m 29.55s , -00d 19m 40.6s) | C | 60 | 16.5 |
24577 | 2026-03-12 16:35:53 | MASTER-Kislovodsk | (01h 55m 57.24s , -04d 08m 01.4s) | C | 60 | 16.8 |
24677 | 2026-03-12 16:37:33 | MASTER-Kislovodsk | (01h 55m 42.13s , -02d 14m 03.2s) | C | 60 | 16.6 |
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 43970
Subject
GRB 260312B: BALROG localization (Fermi Trigger 795001611 / GRB 260312407)
Date
2026-03-12T10:16:35Z (7 months ago)
From
Jochen Greiner at MPE <jcgrog@mpe.mpg.de>
Via
email
T. Preis (University of Innsbruck) & J. Greiner (MPE Garching) report:
The public trigdat data of the Fermi Gamma-ray Burst Monitor (GBM) trigger
795001611 at 09:46:46 on 12 March 2026 were automatically fitted for spectrum
and sky location with BALROG (Burgess et al. 2018, MNRAS 476, 1427;
Berlato et al. 2019, ApJ 873, 60).
The best-fit position is:
RA(2000.0) = 26.3 deg
Decl.(2000.0) = -8.3 deg
The 1 sigma statistical error radius is 2.2 deg.
We estimate an additional systematic error of 1 deg.
Further details are available at:
https://grb.mpe.mpg.de/grb/GRB260312407/
The Healpix map can be downloaded from:
https://grb.mpe.mpg.de/grb/GRB260312407/healpix
The location parameters are available as JSON at:
https://grb.mpe.mpg.de/grb/GRB260312407/json
GCN Circular 43969
Subject
GRB 260312B: Fermi GBM Final Real-time Localization
Date
2026-03-12T09:57:18Z (7 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 09:46:46 UT on 12 Mar 2026, the Fermi Gamma-ray Burst Monitor (GBM) triggered and located GRB 260312B (trigger 795001611.054834 / 260312407).
The on-ground calculated location, using the Fermi GBM trigger data, is RA = 25.9, Dec = -3.9 (J2000 degrees, equivalent to J2000 01h 43m, -3d 53'), with a statistical uncertainty of 1.9 degrees.
The angle from the Fermi LAT boresight is 67.0 degrees.
The skymap can be found here:
https://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2026/bn260312407/quicklook/glg_skymap_all_bn260312407.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/bn260312407/quicklook/glg_healpix_all_bn260312407.fit
The GBM light curve can be found here:
https://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2026/bn260312407/quicklook/glg_lc_medres34_bn260312407.gif