TITLE:   GCN CIRCULAR
NUMBER:  18665
SUBJECT: GRB 151205B: MASTER-NET early  optical observations 
DATE:    15/12/06 00:26:57 GMT
FROM:    Vladimir Lipunov at Moscow State U/Krylov Obs  <lipunov@xray.sai.msu.ru>

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

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

K.Ivanov, S.Yazev, N.M.Budnev, O.Gres, O.Chuvalaev, V.A.Poleshchuk
Irkutsk State University

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

V.Yurkov, Yu.Sergienko, D.Varda, E.Sinyakov
Blagoveschensk Educational State University, Blagoveschensk
21:43:14.53

V.Krushinski, I.Zalozhnih,  A. Popov
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)

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

MASTER II  robotic telescope (MASTER-Net: http://observ.pereplet.ru) 
located in SAAO was pointed to the  GRB151205B (Marshall et. al. GCN 
18659) 28 sec after notice time and 63 sec after trigger time at 21:44:18 
UT in two polarisations. On our first (10s exposure)  set we haven`t found 
optical transient  within SWIFT error-box (ra=02 44 38 dec=-43 28 50 
r=0.050000).
The 5-sigma upper limit has been about 17.0 mag.

We obtain a following early upper limits at a single an coadd images

T_start  T-Ts  T-Tm  Expt. Mlimit  Coadd
--------|----|-----|-----|-------|-------|
21:44:18   63    68    10    17.0   1
21:44:18   63   115    60    18.7   3
21:44:18   63   501   680    20.6  10
21:44:51   96   106    20    17.8   1
21:45:32  137   152    30    18.1   1
21:46:21  187   207    40    18.3   1
21:47:21  246   271    50    18.7   1
21:48:31  316   346    60    19.0   1
21:49:51  396   436    80    19.3   1
21:51:47  513   563   100    19.6   1
21:53:45  630   695   130    19.9   1
21:56:13  778   858   160    20.0   1
...

Ts - is exposure start time
Tm - is exposure middle time
T  - is trigger time

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