TITLE:   GCN CIRCULAR
NUMBER:  28208
SUBJECT: GRB 200803B: MASTER possibly OT discovery 
DATE:    20/08/06 14:09:02 GMT
FROM:    Vladimir Lipunov at Moscow State U/Krylov Obs  <lipunov@xray.sai.msu.ru>

V. Lipunov,  E. Gorbovskoy, V.Kornilov, N.Tyurina, K.Zhirkov, P.Balanutsa,A.Kuznetsov,F.Balakin,
V.Vladimirov, A.Chasovnikov, D. Vlasenko, I.Gorbunov, D.Zimnukhov, V.Topolev, V.Senik, T.Pogrosheva,
D.Kuvshinov(Lomonosov Moscow State University, SAI, Physics Department),
D. Buckley(South African Astronomical Observatory),
A. Tlatov, D. Dormidontov (Kislovodsk Solar Station of the Pulkovo Observatory),
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),
R. Rebolo, M. Serra(The Instituto de Astrofisica de Canarias),
O.A. Gres, N.M. Budnev (Irkutsk State University, API),
A. Gabovich, Yu. Sergienko, V.Yurkov (Blagoveschensk Educational State University)


MASTER Global Robotic Net started Fermi GRB 200803B( Fermi GBM team, GCN 28201)
  errorbox  27 sec after notice time (55 sec after trigger time) at 
2020-08-03 16:53:38 UT, with upper limit up to  18.6 mag. (GCN 28204)
Observations started at twilight at zenith distance = 10 deg, the sun  altitude  was -10.9 deg.
The cover map with discovered OT is  at alert page
https://master.sai.msu.ru/site/master2/event.php?id=1413139

MASTER OT J144603.45-413156.7 discovery (AT2020qvn)

During these alert observations (Fermi inspection, open mode for twin 
MASTER, and fast coverage of large error-box by 8 square deg.)
MASTER-SAAO auto-detection system ( Lipunov et al., "MASTER Global Robotic Net", Advances in Astronomy, 2010, 30L )
  discovered OT source at
(RA, Dec) = 14h 46m 03.45s -41d 31m 56.7s on 2020-08-03.70644 UT.

The OT unfiltered magnitude is 17.9m (mlim=18.1).

The OT is seen in 5 images. There is no any known sources in VIZIER and minor planet at this place

We have reference image on 2017-05-28.87608 UT with unfiltered mlim=20.9m.

Spectral observations are required (it also can be MilkyWay's CV, PSN in 
52" from 6df galaxy (z=0.05128, B=16.96,R=15.97, too far for PSN but can 
be).

The discovery and reference images are available at:

http://master.sai.msu.ru/static/OT/144603.45-413156.7.png

Spectral observations and deep photometry are required.