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GCN Circular 30567

Subject
Swift GRB210731.93: Global MASTER-Net observations report
Date
2021-07-31T22:32:10Z (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-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) was pointed to the Swift GRB210731.93 (trigger No 1062336,20h 01m 15.36s , -28d 02m 31.2s, R=0.05) errorbox 67 sec after trigger time at 2021-07-31 22:22:16 UT, with upper limit up to  18.7 mag. The observations began at zenith distance =  5 deg. The sun  altitude  is -75.2 deg. 

MASTER-IAC robotic telescope  located in Spain (IAC Teide Observatory) was pointed to the Swift GRB210731.93 errorbox 108 sec after trigger time at 2021-07-31 22:22:57 UT, with upper limit up to  16.2 mag. The observations began at zenith distance = 64 deg. The sun  altitude  is -28.8 deg. 

The galactic latitude b = -27 deg., longitude l = 14 deg.


Real time updated cover map and OT discovered available here: 
https://master.sai.msu.ru/site/master2/observ.php?id=1677220

We obtain a following upper limits.  

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

      73 |         MASTER-SAAO |   C |    10 | 17.4 |        
     107 |         MASTER-SAAO |   C |    20 | 17.8 |        
     119 |          MASTER-IAC |  P| |    20 | 14.2 |        
     119 |          MASTER-IAC |  P- |    20 | 15.1 |        
     152 |         MASTER-SAAO |   C |    30 | 18.4 |        
     164 |          MASTER-IAC |  P| |    30 | 16.2 |        
     164 |          MASTER-IAC |  P- |    30 | 15.8 |        
     206 |         MASTER-SAAO |   C |    40 | 18.7 |        
     218 |          MASTER-IAC |  P| |    40 | 15.8 |        
     266 |         MASTER-SAAO | P\  |    10 | 16.7 |        
     292 |         MASTER-SAAO | P\  |    20 | 17.5 |        
     324 |         MASTER-SAAO | P\  |    20 | 16.5 |        
     362 |         MASTER-SAAO | P\  |    30 | 17.6 |        
Filter C is a clear (unfiltred) band. 


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