GRB 261030B
GCN Circular 46119
Subject
Fermi GRB 261030B: Global MASTER-Net observations report
Date
2026-10-30T22:16:20Z (2 days ago)
From
Vladimir Lipunov at Moscow State U/Krylov Obs <lipunov@xray.sai.msu.ru>
Via
email
D.Buckley (SAAO),
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)
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-SAAO robotic telescope [1] located in South Africa (South African Astronomical Observatory) started inspect of the Fermi GRB 261030B ( Fermi GBM team, GCN 46118) errorbox 111 sec after notice time and 144 sec after trigger time at 2026-10-30 21:45:52 UT, with upper limit up to 18.5 mag. The observations began at zenith distance = 51 deg. The sun altitude is -43.1 deg.
The galactic latitude b = -22 deg., longitude l = 262 deg.
Real time updated cover map and OT discovered available here:
https://master.sai.msu.ru/site/master2/observ.php?id=3532170
We obtain a following upper limits.
Tmid-T0 | Date Time | Site | Coord (J2000) |Filt.| Expt. | Limit| Comment
_________|_____________________|_____________________|____________________________________|_____|_______|_______|________
160 | 2026-10-30 21:45:52 | MASTER-SAAO | (06h 11m 48.56s , -52d 11m 55.8s) | C | 30 | 17.4 |
160 | 2026-10-30 21:45:52 | MASTER-SAAO | (06h 08m 55.01s , -51d 56m 32.2s) | C | 30 | 17.3 |
223 | 2026-10-30 21:46:50 | MASTER-SAAO | (06h 18m 25.85s , -53d 12m 00.6s) | C | 40 | 17.6 |
278 | 2026-10-30 21:46:50 | MASTER-SAAO | (06h 18m 25.85s , -53d 12m 00.6s) | C | 150 | 18.5 | Coadd
223 | 2026-10-30 21:46:50 | MASTER-SAAO | (06h 15m 28.48s , -52d 56m 37.8s) | C | 40 | 17.6 |
278 | 2026-10-30 21:46:50 | MASTER-SAAO | (06h 15m 28.47s , -52d 56m 37.9s) | C | 150 | 18.4 | Coadd
287 | 2026-10-30 21:47:49 | MASTER-SAAO | (06h 18m 25.91s , -53d 12m 00.6s) | C | 50 | 18.0 |
287 | 2026-10-30 21:47:49 | MASTER-SAAO | (06h 15m 28.48s , -52d 56m 38.5s) | C | 50 | 18.0 |
361 | 2026-10-30 21:48:58 | MASTER-SAAO | (06h 18m 25.91s , -53d 12m 00.7s) | C | 60 | 18.0 |
361 | 2026-10-30 21:48:58 | MASTER-SAAO | (06h 15m 28.44s , -52d 56m 39.1s) | C | 60 | 17.8 |
622 | 2026-10-30 21:53:19 | MASTER-SAAO | (06h 44m 59.79s , -52d 59m 04.0s) | C | 60 | 16.9 |
682 | 2026-10-30 21:53:19 | MASTER-SAAO | (06h 44m 59.79s , -52d 59m 03.9s) | C | 180 | 17.1 | Coadd
622 | 2026-10-30 21:53:19 | MASTER-SAAO | (06h 42m 02.43s , -52d 43m 48.7s) | C | 60 | 16.8 |
682 | 2026-10-30 21:53:19 | MASTER-SAAO | (06h 42m 02.43s , -52d 43m 48.8s) | C | 180 | 17.1 | Coadd
701 | 2026-10-30 21:54:38 | MASTER-SAAO | (06h 44m 59.82s , -52d 59m 03.1s) | C | 60 | 16.7 |
701 | 2026-10-30 21:54:38 | MASTER-SAAO | (06h 42m 02.41s , -52d 43m 48.4s) | C | 60 | 16.7 |
780 | 2026-10-30 21:55:57 | MASTER-SAAO | (06h 44m 59.77s , -52d 59m 02.8s) | C | 60 | 15.8 |
780 | 2026-10-30 21:55:57 | MASTER-SAAO | (06h 42m 02.31s , -52d 43m 48.4s) | C | 60 | 16.0 |
859 | 2026-10-30 21:57:16 | MASTER-SAAO | (06h 44m 59.72s , -52d 59m 02.8s) | C | 60 | 17.9 |
859 | 2026-10-30 21:57:16 | MASTER-SAAO | (06h 42m 02.22s , -52d 43m 48.8s) | C | 60 | 17.7 |
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 46118
Subject
GRB 261030B: Fermi GBM Final Real-time Localization
Date
2026-10-30T21:54:00Z (2 days 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 21:43:27 UT on 30 Oct 2026, the Fermi Gamma-ray Burst Monitor (GBM) triggered and located GRB 261030B (trigger 815089412.659158 / 261030905).
The on-ground calculated location, using the Fermi GBM trigger data, is RA = 101.4, Dec = -52.8 (J2000 degrees, equivalent to J2000 06h 45m, -52d 47'), with a statistical uncertainty of 5.8 degrees.
The angle from the Fermi LAT boresight is 24.0 degrees.
The skymap can be found here:
https://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2026/bn261030905/quicklook/glg_skymap_all_bn261030905.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/bn261030905/quicklook/glg_healpix_all_bn261030905.fit
The GBM light curve can be found here:
https://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2026/bn261030905/quicklook/glg_lc_medres34_bn261030905.gif