GCN Circular 45799
Fermi GRB 261003A: Global MASTER-Net observations report
From: Vladimir Lipunov at Moscow State U/Krylov Obs
Issued: 2026-10-03 02:45 UTC
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 (Lomonosov MSU)
D.Buckley (SAAO),
A. Gabovich, V.Yurkov (Blagoveschensk Educational StateUniversity)
A.Sosnovskij (Lomonosov MSU)
A. Tlatov, D. Dormidontov (Kislovodsk Solar Station of the Pulkovo Observatory)
L.Carrasco, J.R.Valdes, V.Chavushyan, V.M.Patino Alvarez, J.Martinez,
A.R.Corella, L.H.Rodriguez (INAOE, Guillermo Haro Astrophysics Observatory)
R.Rebolo (The Instituto de Astrofisica de Canarias)
O.Gress, N.Budnev(ISU)
M. Segura, F. Podesta, R.Podesta, E. Gonzalez (Observatorio Astronomico Felix Aguilar (OAFA)
MASTER-Tavrida robotic telescope [1] located in Russia (Lomonosov MSU, SAI Crimea astronomical station) started inspect of the Fermi GRB 261003A ( Fermi GBM team, GCN 45797) errorbox 4620 sec after notice time and 4654 sec after trigger time at 2026-10-03 02:36:10 UT, with upper limit up to 16.5 mag. Observations started at twilight. The observations began at zenith distance = 80 deg. The sun altitude is -12.5 deg.
The galactic latitude b = 4 deg., longitude l = 83 deg.
Real time updated cover map and OT discovered available here:
GRB261003.05 page :: MASTER Database :: MASTER Net (master.sai.msu.ru)
We obtain a following upper limits.
Tmid-T0 | Date Time | Site | Coord (J2000) |Filt.| Expt. | Limit| Comment
_________|_____________________|_____________________|____________________________________|_____|_______|_______|________
4660 | 2026-10-03 02:36:10 | MASTER-Tavrida | (19h 21m 38.90s , +53d 18m 43.8s) | C | 10 | 15.7 |
4673 | 2026-10-03 02:36:22 | MASTER-Tavrida | (19h 21m 38.98s , +53d 18m 43.0s) | C | 10 | 15.7 |
4673 | 2026-10-03 02:36:23 | MASTER-Tavrida | (19h 21m 33.52s , +53d 20m 03.7s) | C | 10 | 14.2 |
4687 | 2026-10-03 02:36:36 | MASTER-Tavrida | (19h 21m 39.10s , +53d 18m 43.1s) | C | 10 | 15.8 |
4687 | 2026-10-03 02:36:36 | MASTER-Tavrida | (19h 21m 33.60s , +53d 20m 04.4s) | C | 10 | 14.1 |
4705 | 2026-10-03 02:36:50 | MASTER-Tavrida | (19h 21m 39.22s , +53d 18m 43.0s) | C | 20 | 16.2 |
4706 | 2026-10-03 02:36:50 | MASTER-Tavrida | (19h 21m 33.74s , +53d 20m 04.6s) | C | 20 | 14.6 |
4729 | 2026-10-03 02:37:13 | MASTER-Tavrida | (19h 21m 39.35s , +53d 18m 43.2s) | C | 20 | 16.0 |
4756 | 2026-10-03 02:37:36 | MASTER-Tavrida | (19h 21m 39.48s , +53d 18m 43.1s) | C | 30 | 16.2 |
4756 | 2026-10-03 02:37:36 | MASTER-Tavrida | (19h 21m 33.97s , +53d 20m 05.5s) | C | 30 | 14.6 |
4790 | 2026-10-03 02:38:10 | MASTER-Tavrida | (19h 21m 39.60s , +53d 18m 43.8s) | C | 30 | 16.3 |
4790 | 2026-10-03 02:38:10 | MASTER-Tavrida | (19h 21m 34.10s , +53d 20m 06.4s) | C | 30 | 14.6 |
4829 | 2026-10-03 02:38:43 | MASTER-Tavrida | (19h 21m 39.63s , +53d 18m 44.3s) | C | 40 | 16.4 |
4829 | 2026-10-03 02:38:44 | MASTER-Tavrida | (19h 21m 34.15s , +53d 20m 07.0s) | C | 40 | 14.9 |
4878 | 2026-10-03 02:39:27 | MASTER-Tavrida | (19h 21m 39.67s , +53d 18m 45.2s) | C | 50 | 16.5 |
4878 | 2026-10-03 02:39:27 | MASTER-Tavrida | (19h 21m 34.17s , +53d 20m 08.5s) | C | 50 | 14.9 |
4937 | 2026-10-03 02:40:21 | MASTER-Tavrida | (19h 21m 39.72s , +53d 18m 46.8s) | C | 60 | 16.5 |
4937 | 2026-10-03 02:40:21 | MASTER-Tavrida | (19h 21m 34.22s , +53d 20m 10.4s) | C | 60 | 14.9 |
5007 | 2026-10-03 02:41:27 | MASTER-Tavrida | (19h 21m 39.75s , +53d 18m 48.6s) | C | 70 | 16.5 |
5007 | 2026-10-03 02:41:27 | MASTER-Tavrida | (19h 21m 34.25s , +53d 20m 12.4s) | C | 70 | 14.9 |
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
Every one of the gamma-ray bursts GCN reports is posted here.
Relayed automatically from NASA's General Coordinates Network.
Transient Alerts » in reply to GRB 261003A
In plain words Routine
On 3 October 2026, NASA's Fermi space telescope picked up a brief flash of gamma rays (the most energetic form of light) from a spot in the northern sky, in the direction of the constellation Cygnus. The flash looks like a short gamma-ray burst, a type that usually lasts under about two seconds and is often linked to the merger of two dense dead stars. Glowbug, a gamma-ray detector on the International Space Station, also saw it, as a single peak lasting about a tenth of a second. Fermi could only place it within a large patch of sky, roughly 20 degrees across, and a Russian-led robotic telescope network searched part of that area about 77 minutes later and found no new visible source down to a certain faintness. No distance or afterglow (fading light from the explosion) has been reported so far.
How unusual is it? Short bursts are a regular catch for Fermi, and this one has only a rough location, no afterglow and no measured distance. It would become more interesting if a faint afterglow or a host galaxy were found, or if a gravitational-wave signal were tied to it.
Written by an AI model (claude-sonnet-5-5) from the official reports in this thread; last updated . It may contain mistakes: the reports themselves are the authority.
Fermi GRB 261003A: Global MASTER-Net observations report