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GCN Circular 39801

Subject
Fermi GRB 250321A: Global MASTER-Net observations report
Date
2025-03-21T08:31:06Z (5 days ago)
From
Vladimir Lipunov at Moscow State U/Krylov Obs <lipunov@xray.sai.msu.ru>
Via
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 GRB 250321A ( Fermi GBM team, GCN 39793Loading...
 
 ) errorbox  25226 sec after notice time and 25261 sec after trigger time at 2025-03-21 07:43:40 UT, with upper limit up to  17.1 mag. The observations began at zenith distance = 82 deg. The sun  altitude  is -37.1 deg. 

The galactic latitude b = -6 deg., longitude l = 56 deg.


Real time updated cover map and OT discovered available here: 
https://master.sai.msu.ru/site/master2/observ.php?id=2818762

We obtain a following upper limits.  

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

   25341 | 2025-03-21 07:43:40 |         MASTER-OAFA | (19h 30m 40.40s , +20d 25m 41.2s) |   C |   160 | 16.0 |        
   25537 | 2025-03-21 07:46:56 |         MASTER-OAFA | (19h 30m 47.85s , +20d 25m 03.0s) |   C |   160 | 16.4 |        
   25733 | 2025-03-21 07:50:11 |         MASTER-OAFA | (19h 30m 42.54s , +20d 24m 22.3s) |   C |   160 | 16.7 |        
   26355 | 2025-03-21 08:00:33 |         MASTER-OAFA | (19h 30m 43.53s , +20d 26m 11.7s) |   C |   160 | 16.4 |        
   27421 | 2025-03-21 08:19:20 |         MASTER-OAFA | (19h 30m 53.70s , +20d 27m 42.1s) |   C |    40 | 17.0 |        
   27431 | 2025-03-21 08:19:20 |         MASTER-OAFA | (19h 40m 32.05s , +20d 50m 27.7s) |   C |    60 | 16.6 |        
   27559 | 2025-03-21 08:20:37 |         MASTER-OAFA | (19h 30m 47.78s , +20d 27m 00.4s) |   C |   160 | 16.8 |        
   27569 | 2025-03-21 08:20:38 |         MASTER-OAFA | (19h 41m 30.19s , +20d 47m 56.2s) |   C |   180 | 16.7 |        
   27694 | 2025-03-21 08:23:53 |         MASTER-OAFA | (19h 30m 54.58s , +20d 27m 29.9s) |   C |    40 | 17.1 |        
Filter C is a clear (unfiltred) band. 


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