GCN Circular 44098

Subject
Fermi GRB 260323A: Global MASTER-Net observations report
Event
GRB 260323A
Date
2026-03-24T00:15:25Z (12 days ago)
From
Vladimir Lipunov at Moscow State U/Krylov Obs <lipunov@xray.sai.msu.ru>
Via
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-OAFA robotic telescope  [1]  located in Argentina (OAFA observatory of San Juan National University) started inspect of the Fermi GRB 260323A ( Fermi GBM team, GCN 44097Loading...
 
 ) errorbox  143 sec after notice time and 173 sec after trigger time at 2026-03-23 23:54:21 UT, with upper limit up to  20.1 mag. Observations started at twilight.  The observations began at zenith distance = 43 deg. The sun  altitude  is -16.3 deg. 

The galactic latitude b = -27 deg., longitude l = 289 deg.


Real time updated cover map and OT discovered available here: 
https://master.sai.msu.ru/site/master2/observ.php?id=3206970

We obtain a following upper limits.  

Tmid-T0  |      Date Time      |          Site       |             Coord (J2000)          |Filt.| Expt. | Limit| Comment
_________|_____________________|_____________________|____________________________________|_____|_______|_______|________

     188 | 2026-03-23 23:54:21 |         MASTER-OAFA | (06h 02m 40.77s , -72d 38m 38.2s) |   C |    30 | 18.8 |        
     229 | 2026-03-23 23:54:57 |         MASTER-OAFA | (06h 02m 40.97s , -72d 38m 38.5s) |   C |    40 | 18.9 |        
     280 | 2026-03-23 23:55:43 |         MASTER-OAFA | (06h 02m 41.22s , -72d 38m 38.9s) |   C |    50 | 19.2 |        
     341 | 2026-03-23 23:56:39 |         MASTER-OAFA | (06h 02m 41.55s , -72d 38m 39.0s) |   C |    60 | 19.3 |        
     650 | 2026-03-24 00:01:17 |         MASTER-OAFA | (06h 42m 20.00s , -76d 51m 39.3s) |   C |   120 | 20.1 |        
     786 | 2026-03-24 00:03:23 |         MASTER-OAFA | (06h 42m 20.80s , -76d 51m 40.5s) |   C |   140 | 20.1 |        
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