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GCN Circular 22055

Subject
GRB 171027A: MASTER-OAFA (Argentina) early prompt optical observations
Date
2017-10-27T10:28:03Z (7 years ago)
From
Vladimir Lipunov at Moscow State U/Krylov Obs <lipunov@xray.sai.msu.ru>
V. Lipunov, E. Gorbovskoy, N.Tyurina, V.Kornilov, D.Kuvshinov, P.Balanutsa, 
A.Kuznetsov, V.V.Chazov, D. Vlasenko, I.Gorbunov, A.V.Krylov
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)

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


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

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

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


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

MASTER II  robotic telescope (MASTER-Net: http://observ.pereplet.ru) 
located in OAFA was pointed to the  GRB171027A ( D'Avanzo et al., GCN 
Circ 22053 ) 26 sec after notice time 
and 71 sec after trigger time at 2017-10-27 08:24:17 UT. On our first (10s 
exposure)  set we haven`t found optical transient  within SWIFT error-box 
(ra=61.6708 dec=-2.60556 r=0.05). The 5-sigma upper limit has been about 
17.5 mag . This and next 2 images  are prompt optical limit because GRB 
duration is ~ 120 
sec (D'Avanzo et al., GCN Circ 22053 )



The OT limit are:

   ID       UT     Exp          Type             Limit

103456  08:24:17   10      Alert (SWIFT)        17.5
103463  08:24:17   70   SumAlert (SWIFT)        19.0
103473  08:24:17  550   SumAlert (SWIFT)        20.0
103457  08:25:09   20      Alert (SWIFT)        18.1
103459  08:26:10   40	   Alert (SWIFT)	18.6
103467  08:27:34  210   SumAlert (SWIFT)        19.5
103460  08:27:34   50      Alert (SWIFT)        18.6
103461  08:29:07   70      Alert (SWIFT)        18.9
103462  08:31:00   90      Alert (SWIFT)        19.0
103472  08:33:15  450   SumAlert (SWIFT)        19.9
103464  08:33:15  120      Alert (SWIFT)        19.2
103466  08:36:00  150      Alert (SWIFT)        19.2
103468  08:39:15  180      Alert (SWIFT)        19.3
103476  08:43:00  540   SumAlert (SWIFT)        19.5
103470  08:43:00  180      Alert (SWIFT)        19.0
103471  08:46:43  180      Alert (SWIFT)        18.8
103474  08:50:25  180      Alert (SWIFT)        18.4
103477  08:54:08  180      Alert (SWIFT)        18.1
103478  08:57:53  180      Alert (SWIFT)        18.1


The observations made on zenit distance = 41 degrees, galaxy latitude b = 
-37 degree. The moon (45 % bright part) below the horizon (The altitude of 
the Moon is -33 degree ). Observations started at twilight.
The sun  altitude  is -16.5 degree.
The object can be observed till sunrise at 2017-10-27 09:44:50


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