[vsnet-grb-info 20500] GRB 180404B: MASTER-OAFA OT observation

[GCN Circulars]

TITLE:   GCN CIRCULAR
NUMBER:  22596
SUBJECT: GRB 180404B: MASTER-OAFA OT observation
DATE:    18/04/04 09:39:48 GMT
FROM:    Vladimir Lipunov at Moscow State U/Krylov Obs  <lipunov at xray.sai.msu.ru>

V. Lipunov, E. Gorbovskoy, V.Kornilov, N.Tyurina, 
A.Kuznetsov, V.V.Chazov, A.V. Krylov, I. Gorbunov, D. Vlasenko, 
D.Zimnukhov, D.Kuvshinov, P.Balanutsa
Lomonosov Moscow State University,
Sternberg Astronomical Institute, Moscow State University

R. Podesta, F. Podesta, C. Lopez, C.Francile
Observatorio Astronomico Felix Aguilar (OAFA)

H.Levato, C. Saffe
Instituto de Ciencias Astronomicas, de la Tierra y del Espacio (ICATE)

R. Rebolo, M. Serra, N. Lodieu, G. Israelian, L. Suarez-Andres
The Instituto de Astrofisica de Canarias

D. Buckley
South African Astronomical Observatory

O. Gres, N.M. Budnev, Yu.Ishmuhametova
Irkutsk State University

A. Tlatov, V.Senik, D. Dormidontov
Kislovodsk Solar Station of the Pulkovo Observatory

A. Gabovich, V. Yurkov, Yu. Sergienko
Blagoveschensk Educational State University, Blagoveschensk


MASTER-OAFA robotic telescope (MASTER-Net: http://observ.pereplet.ru) 
located in Argentina was pointed to the  GRB180404B (LaPorte et al. GCN 
22590; Beardmore et al. GCN 22594) 27 sec after notice time and 45 sec 
after trigger time at 2018-04-04 02:12:29 UT.
On our first 10s exposure  image with unfiltered mlim=16.5 (5-sigma) we 
don't found optical transient  within SWIFT error-box (ra=53.3792 
dec=-50.195 r=0.05 LaPorte et al. GCN 22590)

MASTER auto-detection system detected OT with RA,Dec=53.392900; 
-50.214903
and unfiltered m_OT = 18.4 (automatic reduction)
on the summary image with 670s exposition started on 2018-04-04 02:12:29 
(mlim=19.7)

The message may be cited.


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The observations started at zenit distance = 73 degrees, galaxy latitude b 
= -51 degree.
The moon (86 % bright part) is 16 degrees above the horizon. The distance 
between  moon and  object is 115
The sun  altitude was -46.8 degree.