GCN Circular 22273

N.Tyurina, V. Lipunov, E. Gorbovskoy,V.Kornilov, D.Kuvshinov, A.V.Krylov, 
I.Gorbunov, P.Balanutsa, A.Kuznetsov, V.V.Chazov, D. Vlasenko
Lomonosov Moscow State University, Sternberg Astronomical Institut of MSU

R.Podesta, C.Lopez, F. Podesta Observatorio Astronomico Felix Aguilar (OAFA),
National University of San Juan, Argentina

H. Levato, C. Saffe
Instituto de Ciencias Astronomicas,de la Tierra y del Espacio (ICATE),
San Juan, Argentina

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

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

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

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

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


MASTER-IAC  robotic telescope (MASTER-Net: http://observ.pereplet.ru) 
located in IAC (Tenerife) was pointed to the Swift  GRB171222A (Racusin et 
al.,  GCN  #22265;) 47159 seconds (~ 13h ) 
after trigger time at 2017-12-23  05:31:03 UT.
The 5-sigma upper limit has been about 19.3  at single (180 s) and 20.9 at 
coadd (10x180 = 1800 s ) images.

We see OT detected by (Perley et al., GCN #22269; de Ugarte Postigo et 
al., GCN #22272 ) at X-ray position (Osborne et al.,  GCN #22266; D'Elia 
et al., GCN #22271).

The OT unfiltered magnitude is about ~ 21.

The observations made on zenit distance = 11 degrees, galaxy latitude b = 
52 degree.
The moon (21 % bright part) below the horizon (The altitude of the Moon is 
-73 degree ).
The sun  altitude  is -30.5 degree.
The object can be observed till sunrise at 2017-12-23 07:54:43 .

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