[vsnet-grb-info 27635] GRB 210330A: MASTER optical observation

[GCN Circulars]

TITLE:   GCN CIRCULAR
NUMBER:  29738
SUBJECT: GRB 210330A: MASTER optical observation 
DATE:    21/03/30 21:27:39 GMT
FROM:    Vladimir Lipunov at Moscow State U/Krylov Obs  <lipunov at xray.sai.msu.ru>

V. Lipunov, A.Chasovnikov, F.Balakin, V.Kornilov, E.Gorbovskoy,P.Balanutsa, V.Vladimirov, A.Kuznetsov,K.Zhirkov,D. Vlasenko, 
N.Tiurina, I.Gorbunov, D.Zimnukhov, V.Senik, V.Topolev, D.Cheryasov (Lomonosov Moscow State University, SAI, Physics Department),
D. Buckley (South African Astronomical Observatory),
O.A. Gres, N.M. Budnev (Irkutsk State University, API),
R. Podesta, C.Lopez, F. Podesta, C.Francile (Observatorio Astronomico FelixAguilar OAFA),
R. Rebolo, M. Serra(The Instituto de Astrofisica de Canarias),
A. Tlatov, D. Dormidontov (Kislovodsk Solar Station of the Pulkovo Observatory),
A. Gabovich, V.Yurkov (Blagoveschensk Educational StateUniversity)

MASTER Global robotic net (MASTER-Net:http://observ.pereplet.ru Lipunov et al.,2010,Advances in Astronomy,2010,30L)
started GECAM  GRB 210330A (D.Y.Guo et al. GCN 29739, Ttrigger=12:45:46.600 UTC, R.A.Dec.: 164.3d,-55.6d, er.-b.=5.1d) 
optical observations at MASTER-SAAO (located in South African Astronomical Observatory) 
17496 sec after trigger time at 2021-03-30 17:37:23 UT at sunset, with 
upper limit up to  18.7 mag.

Observations started at zenith distance = 43 deg. The sun  altitude was -13.6 deg.

The galactic latitude b =  4 deg., longitude l = 288 deg.

Real time updated cover map and OT,that can be discovered, will be available here:
https://master.sai.msu.ru/site/master2/observ.php?id=1580304

There are the following upper limits of the first images

Tmid-T0  |      Date Time      |          Site       |             Coord (J2000)          |Filt.| Expt. | Limit| Comment
_________|_____________________|_____________________|____________________________________|_____|_______|_______|________
    17587 | 2021-03-30 17:37:23 |         MASTER-SAAO | (10h 57m 26.66s , -55d 35m 44.3s) |   C |   180 | 18.7 |
    17787 | 2021-03-30 17:40:43 |         MASTER-SAAO | (10h 57m 26.36s , -55d 34m 44.9s) |   C |   180 | 18.6 |
    17986 | 2021-03-30 17:44:02 |         MASTER-SAAO | (11h 05m 32.80s , -55d 35m 42.8s) |   C |   180 | 18.6 |
Filter C is a clear (unfiltred) band.


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