GRB 260318A
GCN Circular 44066
Subject
GRB 260318A: Glowbug gamma-ray detection
Date
2026-03-21T11:28:43Z (2 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 260318A, which was also detected by Fermi/GBM (GCN 44049), GECAM-B (GCN 44052), and SVOM/GRM (GCN 44055).
Using an adaptive window with a resolution of 32-ms, the burst onset is determined to be 2026-03-18 22:35:52.696 with a duration of 7.7 s and a total significance of about 18.1 sigma. The light curve comprises two peaks at ~T0+2s and ~T0+6s.
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 44055
Subject
GRB 260318A: SVOM/GRM observation
Date
2026-03-20T06:30:30Z (2 months ago)
From
yzh807926@163.com
Via
Web form
SVOM/GRM team: Zheng-Hang Yu, Chao Zheng, Chen-Wei Wang, Yue Huang, Shi-Jie Zheng, Shao-Lin Xiong, Shuang-Nan Zhang (IHEP)
SVOM/ECLAIRs team: Hui Yang (IRAP)
Report on behalf of the SVOM team:
SVOM/GRM was triggered in-flight by a burst GRB 260318A (SVOM trigger reference: sb26031805) at 2026-03-18T22:36:00.000 UTC (T0), which is also detected by Fermi/GBM (Fermi GBM team, GCN #44049).
With the event-by-event data downloaded through the X-band ground station, the GRM light curve shows that this burst consists of a precursor followed by a main episode with two peaks a T90 of 28.5 +7.0/-8.0 s in the 15-5000 keV band.
The SVOM/GRM light curve can be found here:
https://www.bursthub.cn//admin/static/svgrb260318A.png
In addition, the position of this burst, as determined by Fermi/GBM (RA= 303.6, DEC= 57.0 GCN#44049), is located at about 164 degrees from the SVOM optical axis, which is outside the ECLAIRs field of view.
With this localization, the time-averaged spectrum from T0-16 to T0+10 s is best fitted by a power law function. The power law index is -2.55 +0.17/-0.16. The event fluence (10-1000 keV) in this time interval is (6.72 +1.45/-1.02)E-05 erg/cm^2.
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: Zheng-Hang Yu(IHEP)(zhyu@ihep.ac.cn)
GCN Circular 44052
Subject
GRB 260318A: GECAM-B observation
Date
2026-03-19T15:47:49Z (2 months ago)
From
yzh807926@163.com
Via
Web form
Zheng-Hang Yu, Chen-Wei Wang, Shao-Lin Xiong (IHEP) report on behalf of GECAM team:
GECAM-B was triggered in-flight by GRB 260318A, at 2026-03-18T22:35:52.600 UTC (denoted as T0), which is also detected by Fermi/GBM ((Fermi GBM team, GCN #44049).
According to the GECAM-B light curves in about 70-6000 keV, this burst mainly consists of multiple pulses with a duration (T90) of 19.5 +3.0/-2.5 s.
The GECAM-B light curve can be found here:
https://www.bursthub.cn//admin/static/gecambgrb260318A.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 44050
Subject
Fermi GRB 260318A: Global MASTER-Net observations report
Date
2026-03-18T23:00:55Z (2 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 260318A ( Fermi GBM team, GCN 44049) errorbox 572 sec after notice time and 596 sec after trigger time at 2026-03-18 22:45:44 UT, with upper limit up to 18.1 mag. The observations began at zenith distance = 62 deg. The sun altitude is -43.5 deg.
The galactic latitude b = 12 deg., longitude l = 92 deg.
Real time updated cover map and OT discovered available here:
https://master.sai.msu.ru/site/master2/observ.php?id=3194853
We obtain a following upper limits.
Tmid-T0 | Date Time | Site | Coord (J2000) |Filt.| Expt. | Limit| Comment
_________|_____________________|_____________________|____________________________________|_____|_______|_______|________
657 | 2026-03-18 22:45:44 | MASTER-Kislovodsk | (20h 14m 11.39s , +56d 41m 32.7s) | P| | 120 | 17.6 |
797 | 2026-03-18 22:48:04 | MASTER-Kislovodsk | (20h 14m 11.18s , +56d 41m 32.8s) | P| | 120 | 17.4 |
938 | 2026-03-18 22:50:25 | MASTER-Kislovodsk | (20h 14m 11.08s , +56d 41m 36.1s) | P| | 120 | 18.1 |
1078 | 2026-03-18 22:52:45 | MASTER-Kislovodsk | (20h 14m 11.06s , +56d 41m 40.9s) | P| | 120 | 18.0 |
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 44049
Subject
GRB 260318A: Fermi GBM Final Real-time Localization
Date
2026-03-18T22:46:23Z (2 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 22:35:47 UT on 18 Mar 2026, the Fermi Gamma-ray Burst Monitor (GBM) triggered and located GRB 260318A (trigger 795566152.456906 / 260318942).
The on-ground calculated location, using the Fermi GBM trigger data, is RA = 303.6, Dec = 57.0 (J2000 degrees, equivalent to J2000 20h 14m, 57d 00'), with a statistical uncertainty of 1.0 degrees.
The angle from the Fermi LAT boresight is 17.0 degrees.
The skymap can be found here:
https://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2026/bn260318942/quicklook/glg_skymap_all_bn260318942.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/bn260318942/quicklook/glg_healpix_all_bn260318942.fit
The GBM light curve can be found here:
https://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2026/bn260318942/quicklook/glg_lc_medres34_bn260318942.gif