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GCN Circular 40463

Subject
MAXI GRB250515.65: Global MASTER-Net observations report
Date
2025-05-16T02:52:05Z (8 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-SAAO robotic telescope  (Global MASTER-Net: http://observ.pereplet.ru, Lipunov et al., 2010, Advances in Astronomy, vol. 2010, 30L)  located in South Africa (South African Astronomical Observatory) started inspect of the MAXI GRB250515.65 (trigger No 10849998,21h 14m 24.00s , -80d 30m 00.0s, R=1) errorbox  10 sec after notice time and 40345 sec after trigger time at 2025-05-16 02:41:33 UT, with upper limit up to  19.0 mag. The observations began at zenith distance = 50 deg. The sun  altitude  is -33.6 deg. 

MASTER-OAFA robotic telescope  located in Argentina (OAFA observatory of San Juan National University) started inspect of the MAXI GRB250515.65 errorbox  79 sec after notice time and 40414 sec after trigger time at 2025-05-16 02:42:42 UT, with upper limit up to  18.6 mag. The observations began at zenith distance = 61 deg. The sun  altitude  is -62.8 deg. 

The galactic latitude b = -33 deg., longitude l = 312 deg.


Real time updated cover map and OT discovered available here: 
https://master.sai.msu.ru/site/master2/observ.php?id=2871800

We obtain a following upper limits.  

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

   40376 | 2025-05-16 02:41:33 |         MASTER-SAAO | (21h 16m 32.15s , -80d 50m 43.5s) |   C |    60 | 18.1 |        
   40436 | 2025-05-16 02:41:33 |         MASTER-SAAO | (21h 16m 32.15s , -80d 50m 43.5s) |   C |   180 | 19.0 |  Coadd 
   40495 | 2025-05-16 02:42:42 |         MASTER-OAFA | (20h 13m 48.68s , -81d 25m 05.7s) |   C |   160 | 17.6 |        
   40505 | 2025-05-16 02:42:43 |         MASTER-OAFA | (21h 11m 07.77s , -80d 47m 38.7s) |   C |   180 | 18.6 |        
   40454 | 2025-05-16 02:42:52 |         MASTER-SAAO | (21h 16m 31.94s , -80d 50m 47.8s) |   C |    60 | 18.3 |        
   40534 | 2025-05-16 02:44:11 |         MASTER-SAAO | (21h 16m 31.62s , -80d 50m 49.7s) |   C |    60 | 18.2 |        
   40613 | 2025-05-16 02:45:30 |         MASTER-SAAO | (21h 16m 31.26s , -80d 50m 50.6s) |   C |    60 | 18.2 |        
Filter C is a clear (unfiltred) band. 


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