[vsnet-grb-info 28184] Fermi GRB 210621A: Global MASTER-Net observations report

[GCN Circulars]

TITLE:   GCN CIRCULAR
NUMBER:  30287
SUBJECT: Fermi GRB 210621A: Global MASTER-Net observations report 
DATE:    21/06/21 12:51:43 GMT
FROM:    Vladimir Lipunov at Moscow State U/Krylov Obs  <lipunov at 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) started inspect of the Fermi GRB 210621A ( Fermi GBM team, GCN 30285) errorbox  353 sec after notice time and 399 sec after trigger time at 2021-06-21 10:50:43 UT, with upper limit up to  15.2 mag. Observations started at twilight.  The observations began at zenith distance = 75 deg. The sun  altitude  is -9.0 deg. 

The galactic latitude b = -9 deg., longitude l = 327 deg.


Real time updated cover map and OT discovered available here: 
https://master.sai.msu.ru/site/master2/observ.php?id=1641646

We obtain a following upper limits.  

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

     430 | 2021-06-21 10:50:43 |         MASTER-OAFA | (16h 35m 08.88s , -58d 53m 13.5s) |   C |    60 | 15.2 |        
Filter C is a clear (unfiltred) band. 


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