[vsnet-grb-info 20497] GRB 180404A: MASTER-OAFA OT observation

[GCN Circulars]

TITLE:   GCN CIRCULAR
NUMBER:  22593
SUBJECT: GRB 180404A: MASTER-OAFA OT observation
DATE:    18/04/04 05:30:33 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.Chazov, I. Gorbunov, D. Vlasenko, D.Kuvshinov, P.Balanutsa
Lomonosov Moscow State University,
Sternberg Astronomical Institute, Moscow State University

R. Podesta, Carlos Lopez and F. Podesta
Observatorio Astronomico Felix Aguilar (OAFA)

Hugo Levato and Carlos Saffe
Instituto de Ciencias Astronomicas, de la Tierra y del Espacio (ICATE)

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

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

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

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

D. Buckley, S. Potter
South African Astronomical Observatory


MASTER-OAFA  robotic telescope (MASTER-Net: http://observ.pereplet.ru) 
located in Argentina was pointed to the  GRB180404A (Gropp et al. GCN 
22589) 21 sec after notice time and 43 sec after trigger time at 
2018-04-04 00:46:18 UT.
On our first 10s exposure  set we haven`t found optical transient with 
17.4 5-sigma upper limit in
SWIFT XRT error-box (ra=83.549 dec=-37.17 r=4.2").

MASTER auto-detection system detected OT with RA,Dec=5h 34m 11s.66, -37d 
10m 03s.5 with unfiltered m_OT=19.8
on the summary image with 660s exposition started 2018-04-04 00:46:18.938UT,
that was discovered by Swift (Gropp et al. GCN 22589) and confirmed by 
VLT (Selsing et al. GCN 22591)

====================================================================

The observations made on zenit distance = 42 degrees, galaxy latitude b = 
-30 degree.
The moon (87 % bright part) below the horizon (The altitude of the Moon is 
-1 degree ).
The sun  altitude  is -29.7 degree.

The message may be cited.



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