GRB 260523A
GCN Circular 44700
Subject
Fermi GRB 260523A: Global MASTER-Net observations report
Date
2026-05-23T23:46:05Z (7 days 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 260523A ( Fermi GBM team, GCN 44698) errorbox 26626 sec after notice time and 26682 sec after trigger time at 2026-05-23 23:30:53 UT, with upper limit up to 18.5 mag. The observations began at zenith distance = 61 deg. The sun altitude is -17.4 deg.
The galactic latitude b = -33 deg., longitude l = 43 deg.
Real time updated cover map and OT discovered available here:
https://master.sai.msu.ru/site/master2/observ.php?id=3334230
We obtain a following upper limits.
Tmid-T0 | Date Time | Site | Coord (J2000) |Filt.| Expt. | Limit| Comment
_________|_____________________|_____________________|____________________________________|_____|_______|_______|________
26713 | 2026-05-23 23:30:53 | MASTER-Kislovodsk | (21h 01m 49.35s , -06d 30m 25.4s) | C | 60 | 18.3 |
26812 | 2026-05-23 23:32:32 | MASTER-Kislovodsk | (20h 55m 10.53s , -08d 23m 36.1s) | C | 60 | 18.4 |
26911 | 2026-05-23 23:34:11 | MASTER-Kislovodsk | (20h 49m 48.74s , -06d 27m 51.5s) | C | 60 | 18.1 |
27006 | 2026-05-23 23:35:46 | MASTER-Kislovodsk | (20h 58m 00.72s , -04d 36m 04.2s) | C | 60 | 18.3 |
27235 | 2026-05-23 23:39:35 | MASTER-Kislovodsk | (21h 07m 20.43s , -08d 24m 37.0s) | C | 60 | 18.5 |
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 44698
Subject
GRB 260523A: Fermi GBM Final Real-time Localization
Date
2026-05-23T16:16:46Z (7 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 16:06:10 UT on 23 May 2026, the Fermi Gamma-ray Burst Monitor (GBM) triggered and located GRB 260523A (trigger 801245175.681708 / 260523671).
The on-ground calculated location, using the Fermi GBM trigger data, is RA = 315.6, Dec = -6.8 (J2000 degrees, equivalent to J2000 21h 02m, -6d 47'), with a statistical uncertainty of 5.5 degrees.
The angle from the Fermi LAT boresight is 51.0 degrees.
The skymap can be found here:
https://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2026/bn260523671/quicklook/glg_skymap_all_bn260523671.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/bn260523671/quicklook/glg_healpix_all_bn260523671.fit
The GBM light curve can be found here:
https://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2026/bn260523671/quicklook/glg_lc_medres34_bn260523671.gif