GCN 43801: Fermi GRB 260221B: Global MASTER-Net observations report
2026-02-22T02:30:42.876Z | rev 0
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 260221B ( Fermi GBM team, GCN 43800) errorbox 9789 sec after notice time and 9824 sec after trigger time at 2026-02-22 02:02:07 UT, with upper limit up to 15.3 mag. The observations began at zenith distance = 52 deg. The sun altitude is -22.0 deg.
The galactic latitude b = 16 deg., longitude l = 112 deg.
Real time updated cover map and OT discovered available here:
https://master.sai.msu.ru/site/master2/observ.php?id=3150150
We obtain a following upper limits.
Tmid-T0 | Date Time | Site | Coord (J2000) |Filt.| Expt. | Limit| Comment
_________|_____________________|_____________________|____________________________________|_____|_______|_______|________
9855 | 2026-02-22 02:02:07 | MASTER-Kislovodsk | (21h 49m 42.78s , +74d 56m 55.5s) | C | 60 | 12.5 |
9970 | 2026-02-22 02:04:03 | MASTER-Kislovodsk | (21h 29m 11.14s , +73d 03m 13.8s) | C | 60 | 15.3 |
10074 | 2026-02-22 02:05:47 | MASTER-Kislovodsk | (21h 30m 08.15s , +73d 03m 12.4s) | C | 60 | 12.1 |
10227 | 2026-02-22 02:08:19 | MASTER-Kislovodsk | (21h 23m 43.72s , +76d 53m 40.4s) | C | 60 | 14.2 |
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 43800: GRB 260221B: Fermi GBM Final Real-time Localization
2026-02-21T23:29:14.552Z | rev 0
The Fermi GBM team reports the detection of a likely SHORT GRB
At 23:18:22 UT on 21 Feb 2026, the Fermi Gamma-ray Burst Monitor (GBM) triggered and located GRB 260221B (trigger 793408707.776836 / 260221971).
The on-ground calculated location, using the Fermi GBM trigger data, is RA = 328.4, Dec = 75.0 (J2000 degrees, equivalent to J2000 21h 53m, 75d 00'), with a statistical uncertainty of 8.4 degrees.
The angle from the Fermi LAT boresight is 12.0 degrees.
The skymap can be found here:
https://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2026/bn260221971/quicklook/glg_skymap_all_bn260221971.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/bn260221971/quicklook/glg_healpix_all_bn260221971.fit
The GBM light curve can be found here:
https://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2026/bn260221971/quicklook/glg_lc_medres34_bn260221971.gif