TITLE:   GCN CIRCULAR
NUMBER:  25448
SUBJECT: GRB 190821A: MASTER VWFC syncronous optical observations
DATE:    19/08/22 14:09:26 GMT
FROM:    Vladimir Lipunov at Moscow State U/Krylov Obs  <lipunov@xray.sai.msu.ru>

F.Balakin, V. Lipunov, E. Gorbovskoy, V. Kornilov, N.Tyurina,
P.Balanutsa,A.Kuznetsov, F.Balakin, V. Vladimirov, D. Vlasenko,
I. Gorbunov,D.Zimnukhov, V.Senik, A.Chasovnikov, A.Pozdnyakov, A.Chasovnikov,
V.Topolev, D.Kuvshinov(Lomonosov Moscow State University, SAI, Physics
Department),
R. Rebolo, M. Serra (The Instituto de Astrofisica de Canarias IAC),
R. Podesta, C.Lopez, F. Podesta, C.Francile (Observatorio Astronomico Felix
Aguilar OAFA),
H. Levato (Instituto de Ciencias Astronomicas, de la Tierra y del Espacio
ICATE),
D. Buckley (South African Astronomical Observatory SAAO),
O. Gress, 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 very wide field cameras (d=82 mm, FOV = 2x384 sq. degree) 
syncronously observed GRB190821A (D'Ai et al. GCN 25427)  position before, 
during and after trigger time. We do not see OT at Swift XRT (Gropp et al. 
GCN 25444) position up to 12 mag.   The syncronous observation movie is 
avalable here:

http://master.sai.msu.ru/static/MASTER_SAAO_GRB190822A.gif

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 GRB190821A  errorbox  8 sec after 
notice time and 41 sec after trigger time at 2019-08-21 17:10:44 UT, with 
upper limit up to  18.4 mag (Lipunov et al. GCN 25429; GCN 25433). 
Observations 
started at twilight.  We alse do not see OT at Swift XRT.  The 
observations began at zenit distance =  3 deg. The sun  altitude  is -12.4 
deg.

Real time updated cover map and OT discovered available here:
https://master.sai.msu.ru/site/master2/observ.php?id=1111516



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