[vsnet-grb-info 21479] GRB 181228A: Global MASTER-Net OT detection

[GCN Circulars]

TITLE:   GCN CIRCULAR
NUMBER:  23578
SUBJECT: GRB 181228A: Global MASTER-Net  OT detection
DATE:    18/12/28 11:56:32 GMT
FROM:    Vladimir Lipunov at Moscow State U/Krylov Obs  <lipunov at xray.sai.msu.ru>

N.Tyurina, V. Lipunov, E. Gorbovskoy, V.Kornilov,  P.Balanutsa,
A.Kuznetsov, D. Vlasenko, D.Kobtsev
Lomonosov Moscow State University, SAI

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

H. Levato
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

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

O. Gres, N.M. Budnev, S. Yazev, O. Chuvalaev, Irkutsk State University

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


MASTER-OAFA robotic telescope (Global MASTER-Net: 
http://observ.pereplet.ru, Lipunov et al., 2010, Advances in Astronomy, 
vol. 2010, 30L) located in Argentina (OAFA observatory of San Juan 
National University) was pointed to the  GRB181228A (Moss et al., 
GCN #23570) 26 sec after notice 
time and 47 sec after trigger time at 2018-12-28 02:54:05 UT. On our first 
(10s exposure)  set we  found 1 optical transient within SWIFT 
XRT error-box  (Beardmore et al., GCN #23574) brighter than 17.5.


  T-Tmid      Date      Time       Expt.        Ra                Dec           Mag
    s                   UTC         s 
---------|---------------------|-------|-----------------|-----------------|-------
     52   2018-12-28 02:54:05       10   ( 03h 19m 14.80s , +13d 12' 02".8 )    17.0

The 5-sigma upper limit has been about 17.5 mag . Coordinate error ~1".

The galactic latitude b = -35 deg., longitude l = 170 deg.
The observations made on zenit distance = 49 deg.The moon (64 % bright 
part) below the horizon (The altitude of the Moon is -14 deg. ).
The sun  altitude  is -29.6 deg.
The object can be observed till 2018-12-28 06:59:09
The message may be cited.