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GCN Circular 40425

Subject
Fermi GRB 250510B: Global MASTER-Net observations report
Date
2025-05-11T01:31:12Z (2 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  (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 250510B ( Fermi GBM team, GCN 40418Loading...
 
 ) errorbox  62438 sec after notice time and 62477 sec after trigger time at 2025-05-11 00:03:11 UT, with upper limit up to  19.0 mag. The observations began at zenith distance = 27 deg. The sun  altitude  is -28.5 deg. 

The galactic latitude b =  9 deg., longitude l = 250 deg.


Real time updated cover map and OT discovered available here: 
https://master.sai.msu.ru/site/master2/observ.php?id=2866812

We obtain a following upper limits.  

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

   62497 | 2025-05-11 00:03:11 |         MASTER-OAFA | (08h 43m 33.97s , -26d 38m 01.3s) |   C |    40 | 17.5 |        
   62508 | 2025-05-11 00:03:11 |         MASTER-OAFA | (08h 33m 17.64s , -26d 59m 17.6s) |   C |    60 | 18.8 |        
   62575 | 2025-05-11 00:04:28 |         MASTER-OAFA | (08h 51m 56.95s , -24d 43m 41.9s) |   C |    40 | 17.6 |        
   62585 | 2025-05-11 00:04:29 |         MASTER-OAFA | (08h 41m 50.32s , -25d 05m 00.8s) |   C |    60 | 19.0 |        
   62653 | 2025-05-11 00:05:47 |         MASTER-OAFA | (08h 35m 04.55s , -24d 42m 42.7s) |   C |    40 | 17.6 |        
Filter C is a clear (unfiltred) band. 


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