GRB 260926C
GCN Circular 45767
Subject
Fermi GRB 260926C: Global MASTER-Net observations report
Date
2026-09-27T00:30:43Z (a day ago)
From
Vladimir Lipunov at Moscow State U/Krylov Obs <lipunov@xray.sai.msu.ru>
Via
email
M. Segura, F. Podesta, R.Podesta, E. Gonzalez (Observatorio Astronomico Felix Aguilar (OAFA)
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)
MASTER-OAFA robotic telescope [1] located in Argentina (OAFA observatory of San Juan National University) started inspect of the Fermi GRB 260926C ( Fermi GBM team, GCN 45766) errorbox 73 sec after notice time and 121 sec after trigger time at 2026-09-26 23:29:13 UT, with upper limit up to 18.8 mag. Observations started at twilight. The observations began at zenith distance = 48 deg. The sun altitude is -12.4 deg.
The galactic latitude b = -22 deg., longitude l = 58 deg.
Real time updated cover map and OT discovered available here:
https://master.sai.msu.ru/site/master2/observ.php?id=3512447
We obtain a following upper limits.
Tmid-T0 | Date Time | Site | Coord (J2000) |Filt.| Expt. | Limit| Comment
_________|_____________________|_____________________|____________________________________|_____|_______|_______|________
132 | 2026-09-26 23:29:13 | MASTER-OAFA | (20h 54m 33.84s , +10d 06m 45.5s) | C | 20 | 16.7 |
163 | 2026-09-26 23:29:39 | MASTER-OAFA | (20h 54m 33.74s , +10d 06m 45.8s) | C | 30 | 17.1 |
203 | 2026-09-26 23:30:15 | MASTER-OAFA | (20h 54m 33.63s , +10d 06m 46.2s) | C | 40 | 17.2 |
255 | 2026-09-26 23:31:02 | MASTER-OAFA | (20h 54m 33.43s , +10d 06m 45.6s) | C | 50 | 17.4 |
317 | 2026-09-26 23:31:58 | MASTER-OAFA | (20h 54m 33.24s , +10d 06m 44.5s) | C | 60 | 17.6 |
388 | 2026-09-26 23:33:05 | MASTER-OAFA | (20h 54m 33.02s , +10d 06m 43.2s) | C | 70 | 17.6 |
659 | 2026-09-26 23:37:10 | MASTER-OAFA | (20h 54m 34.87s , +10d 00m 56.5s) | C | 120 | 18.0 |
795 | 2026-09-26 23:39:17 | MASTER-OAFA | (20h 54m 35.01s , +10d 01m 01.0s) | C | 140 | 18.1 |
910 | 2026-09-26 23:39:17 | MASTER-OAFA | (20h 54m 35.01s , +10d 01m 01.0s) | C | 370 | 18.8 | Coadd
956 | 2026-09-26 23:41:43 | MASTER-OAFA | (20h 54m 35.09s , +10d 01m 05.4s) | C | 170 | 18.3 |
1078 | 2026-09-26 23:44:39 | MASTER-OAFA | (20h 54m 35.12s , +10d 01m 08.9s) | C | 60 | 17.8 |
1143 | 2026-09-26 23:45:45 | MASTER-OAFA | (20h 54m 35.14s , +10d 01m 10.4s) | C | 60 | 17.9 |
1208 | 2026-09-26 23:46:50 | MASTER-OAFA | (20h 54m 35.17s , +10d 01m 12.2s) | C | 60 | 17.8 |
2106 | 2026-09-27 00:01:47 | MASTER-OAFA | (20h 56m 33.45s , +08d 43m 33.0s) | C | 60 | 17.9 |
2166 | 2026-09-27 00:01:47 | MASTER-OAFA | (20h 56m 33.44s , +08d 43m 33.0s) | C | 180 | 18.6 | Coadd
2182 | 2026-09-27 00:03:03 | MASTER-OAFA | (21h 04m 39.31s , +08d 41m 22.3s) | C | 60 | 18.0 |
2242 | 2026-09-27 00:03:03 | MASTER-OAFA | (21h 04m 39.31s , +08d 41m 22.3s) | C | 180 | 18.6 | Coadd
2261 | 2026-09-27 00:04:22 | MASTER-OAFA | (21h 04m 42.29s , +08d 43m 17.3s) | C | 60 | 17.9 |
2337 | 2026-09-27 00:05:38 | MASTER-OAFA | (21h 04m 36.92s , +08d 42m 20.4s) | C | 60 | 17.9 |
2413 | 2026-09-27 00:06:55 | MASTER-OAFA | (20h 56m 31.52s , +08d 43m 47.2s) | C | 60 | 18.0 |
2490 | 2026-09-27 00:08:12 | MASTER-OAFA | (21h 04m 42.71s , +08d 42m 23.8s) | C | 60 | 17.9 |
2568 | 2026-09-27 00:09:29 | MASTER-OAFA | (20h 56m 31.51s , +08d 41m 50.9s) | C | 60 | 18.0 |
2648 | 2026-09-27 00:10:49 | MASTER-OAFA | (20h 56m 54.23s , +12d 31m 12.5s) | C | 60 | 17.8 |
2708 | 2026-09-27 00:10:49 | MASTER-OAFA | (20h 56m 54.24s , +12d 31m 12.5s) | C | 180 | 18.4 | Coadd
2727 | 2026-09-27 00:12:09 | MASTER-OAFA | (21h 05m 05.78s , +12d 29m 38.6s) | C | 60 | 17.8 |
2787 | 2026-09-27 00:12:09 | MASTER-OAFA | (21h 05m 05.78s , +12d 29m 38.6s) | C | 180 | 18.5 | Coadd
2804 | 2026-09-27 00:13:25 | MASTER-OAFA | (21h 05m 08.67s , +12d 30m 49.4s) | C | 60 | 17.9 |
2880 | 2026-09-27 00:14:42 | MASTER-OAFA | (20h 56m 50.95s , +12d 30m 47.6s) | C | 60 | 17.9 |
2958 | 2026-09-27 00:15:59 | MASTER-OAFA | (20h 56m 50.56s , +12d 31m 49.4s) | C | 60 | 17.9 |
3034 | 2026-09-27 00:17:16 | MASTER-OAFA | (21h 05m 09.68s , +12d 30m 24.2s) | C | 60 | 17.9 |
3109 | 2026-09-27 00:18:31 | MASTER-OAFA | (20h 56m 51.56s , +12d 29m 53.4s) | C | 60 | 17.8 |
3184 | 2026-09-27 00:19:46 | MASTER-OAFA | (21h 03m 46.34s , +10d 37m 34.7s) | C | 60 | 17.9 |
3260 | 2026-09-27 00:21:02 | MASTER-OAFA | (21h 11m 54.66s , +10d 35m 16.1s) | C | 60 | 17.9 |
3335 | 2026-09-27 00:22:17 | MASTER-OAFA | (21h 11m 58.63s , +10d 37m 08.8s) | C | 60 | 17.9 |
3410 | 2026-09-27 00:23:32 | MASTER-OAFA | (21h 03m 43.72s , +10d 36m 42.9s) | C | 60 | 18.0 |
3486 | 2026-09-27 00:24:47 | MASTER-OAFA | (21h 03m 43.38s , +10d 37m 45.0s) | C | 60 | 18.0 |
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 45766
Subject
GRB 260926C: Fermi GBM Final Real-time Localization
Date
2026-09-26T23:37:41Z (a day 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 23:27:12 UT on 26 Sep 2026, the Fermi Gamma-ray Burst Monitor (GBM) triggered and located GRB 260926C (trigger 812158037.168668 / 260926977).
The on-ground calculated location, using the Fermi GBM trigger data, is RA = 313.8, Dec = 10.1 (J2000 degrees, equivalent to J2000 20h 55m, 10d 05'), with a statistical uncertainty of 5.3 degrees.
The angle from the Fermi LAT boresight is 46.0 degrees.
The skymap can be found here:
https://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2026/bn260926977/quicklook/glg_skymap_all_bn260926977.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/bn260926977/quicklook/glg_healpix_all_bn260926977.fit
The GBM light curve can be found here:
https://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2026/bn260926977/quicklook/glg_lc_medres34_bn260926977.gif