[vsnet-grb-info 22796] GRB 190627A: MASTER optical counterpart observation

[GCN Circulars]

TITLE:   GCN CIRCULAR
NUMBER:  24895
SUBJECT: GRB 190627A: MASTER optical counterpart observation
DATE:    19/06/28 09:04:55 GMT
FROM:    Vladimir Lipunov at Moscow State U/Krylov Obs  <lipunov at xray.sai.msu.ru>

V. Lipunov, F.Balakin, E. Gorbovskoy, V.Kornilov, N.Tyurina, P.Balanutsa, 
A.Kuznetsov, F.Balakin, V.Vladimirov, D. Vlasenko, I.Gorbunov,D.Zimnukhov, V.Senik, D.Kuvshinov 
(Lomonosov Moscow State University, SAI, Physics Department),

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)

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)
started inspect of Swift GRB 190627A error-box (Sonbas  et al. GCN 24888, trigger 911609, 11:18:31UT, BAT 16h 19m 19.20s , - 5d 17m 31.20s, R=0.05)
  19594 sec after trigger time at 2019-06-27 16:45:05 UT, with upper limit up to  19.4 mag.

MASTER auto-detection system detected optical counterpart
with unfiltered m_OT~18.2 (W=0.2B+0.8R calibrated by USNO-B1 R2,B2)
(OT was discovered by Swift GCN 24888, and also publishied in GCN 24889, GCN 24892, GCN 24893, GCN24894)

Observations started at twilight after sunset.
Observations began at alt. = 30 deg., the sun  altitude  was -12.8 deg.
The galactic latitude b = -60 deg., longitude l = 98 deg.

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