GCN Circular 39749

V.Lipunov, E.Gorbovskoy, N.Tiurina,  P.Balanutsa, , D.Vlasenko, I.Panchenko,
A.Kuznetsov,  G.Antipov,  A.Sankovich, A.Sosnovskij, Yu.Tselik, M.Gulyaev, 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. 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  (Global MASTER-Net: http://observ.pereplet.ru, Lipunov et al., 2010, Advances in Astronomy, vol. 2010, 30L)  located in Argentina (OAFA observatory of San Juan National University) started inspect of the Fermi GRB250317.00 (trigger No 763862734,09h 52m 57.60s , -25d 26m 24.0s, R=6.3) errorbox  117 sec after notice time and 142 sec after trigger time at 2025-03-17 00:07:52 UT, with upper limit up to  17.1 mag. The observations began at zenith distance = 34 deg. The sun  altitude  is -17.2 deg. 

The galactic latitude b = 22 deg., longitude l = 260 deg.


Real time updated cover map and OT discovered available here: 
https://master.sai.msu.ru/site/master2/observ.php?id=2814070

We obtain a following upper limits.  

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

     147 | 2025-03-17 00:07:52 |         MASTER-OAFA | (09h 45m 18.11s , -26d 39m 32.4s) |   C |    10 | 17.1 |        
Filter C is a clear (unfiltred) band. 


The observation and reduction will continue. 
The message may be cited.