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GCN Circular 30761

Subject
Swift GRB210903.58: Global MASTER-Net observations report
Date
2021-09-04T13:56:08Z (3 years ago)
From
Vladimir Lipunov at Moscow State U/Krylov Obs <lipunov@xray.sai.msu.ru>
V. Lipunov, E. Gorbovskoy, V.Kornilov, N.Tyurina, P.Balanutsa, A.Kuznetsov, F.Balakin, 
V.Vladimirov, D. Vlasenko, I.Gorbunov, D.Zimnukhov, V.Senik, T.Pogrosheva,
D.Kuvshinov,  D. Cheryasov
(Lomonosov Moscow State University, SAI, Physics Department),

R. Podesta, C.Lopez, F. Podesta, C.Francile 
(Observatorio Astronomico Felix Aguilar OAFA),

R. Rebolo, M. Serra 
(The Instituto de Astrofisica de Canarias),

D. Buckley 
(South African Astronomical Observatory),

O.A. Gres, N.M. Budnev, O.Ershova 
(Irkutsk State University, API),

A. Tlatov, D. Dormidontov 
(Kislovodsk Solar Station of the Pulkovo Observatory),

V. Yurkov, A. Gabovich, Yu. Sergienko 
(Blagoveschensk Educational State University)




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) was pointed to the Swift GRB210903.58 (trigger No 1071765,12h 24m 38.93s , -62d 40m 53.8s, R=0.0016) errorbox  34282 sec after notice time and 34506 sec after trigger time at 2021-09-03 23:31:41 UT, with upper limit up to  17.3 mag. Observations started at twilight.  The observations began at zenith distance = 59 deg. The sun  altitude  is -16.1 deg. 

MASTER-SAAO robotic telescope  located in South Africa (South African Astronomical Observatory) was pointed to the Swift GRB210903.58 errorbox  41864 sec after notice time and 42088 sec after trigger time at 2021-09-04 01:38:04 UT, with upper limit up to  15.9 mag. The observations began at zenith distance = 84 deg. The sun  altitude  is -41.4 deg. 

The galactic latitude b = -0 deg., longitude l = 300 deg.


Real time updated cover map and OT discovered available here: 
https://master.sai.msu.ru/site/master2/observ.php?id=1708696

We obtain a following upper limits.  

Tmid-T0  |          Site       |Filt.| Expt. | Limit| Comment
_________|_____________________|_____|_______|______|________

   34596 |         MASTER-OAFA |   C |   180 | 16.8 |        
   34796 |         MASTER-OAFA |   C |   180 | 17.3 |        
   36393 |         MASTER-OAFA |   C |   180 | 17.3 |        
   36831 |         MASTER-OAFA |   C |   180 | 16.6 |        
   38319 |         MASTER-OAFA |   C |   180 | 16.5 |        
   38749 |         MASTER-OAFA |   C |   180 | 16.9 |        
   40189 |         MASTER-OAFA |   C |   180 | 16.6 |        
   40622 |         MASTER-OAFA |   C |   180 | 16.9 |        
   42179 |         MASTER-SAAO |   C |   180 | 15.9 |        
   42378 |         MASTER-SAAO |   C |   180 | 15.6 |        
   42623 |         MASTER-OAFA |   C |   180 | 17.0 |        
Filter C is a clear (unfiltred) band. 


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