TITLE:   GCN CIRCULAR
NUMBER:  18169
SUBJECT: GRB 150819A: MASTER-IAC early upper limit 
DATE:    15/08/19 10:46:45 GMT
FROM:    Vladimir Lipunov at Moscow State U/Krylov Obs  <lipunov@xray.sai.msu.ru>

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

V. Lipunov, E. Gorbovskoy,  N.Tyurina, V.Kornilov,
P.Balanutsa,A.Kuznetsov,D.Kuvshinov,
Lomonosov Moscow State University, Sternberg Astronomical Institute

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

D.Buckley, S. Potter, A.Kniazev, M.Kotze
South African Astronomical Observatory

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

V.Yurkov, Yu.Sergienko, D.Varda, E.Sinyakov, A.Gabovich
Blagoveschensk Educational State University, Blagoveschensk

V.Krushinski, I.Zalozhnih
Ural Federal University, Kourovka

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

Claudio Mallamaci, Carlos Lopez and Federico Podest
Observatorio Astronomico Felix Aguilar (OAFA)

MASTER II  robotic telescope (MASTER-Net: http://observ.pereplet.ru) 
located in IAC was pointed to the  GRB150819.03 25 sec after notice time 
and 100 sec after trigger time at 2015-08-19 00:51:51 UT. On our first 
(20s exposure)  set we haven`t found optical transient  within SWIFT 
error-box (Ukwatta, Barthelmy  et al., GCN 18163; Evans, GCN 18165; 
Evans et al., GCN 18167). Zenit distance was aboute ~76 degrees.
The 5-sigma upper limit has been about 17.5 mag
Our results are:

T_start     T-Tmid  Expt.   Mlimit Coadd
00:51:51.6    112     20     17.5    1
00:51:51.6    163     90     18.0    3
00:54:05.5    337    180     18.9    3
00:51:51.6    536    760     19.8   10
01:06:31.0   1995   1800     20.4   10


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