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GCN Circular 23025

GRB 180723.76: MASTER optical observation of the bright long Fermi GBM trigger number 554062193
2018-07-24T08:17:49Z (6 years ago)
Vladimir Lipunov at Moscow State U/Krylov Obs <>
E. Gorbovskoy, V.Lipunov, N.Tiurina, V.Kornilov, A.Kuznetsov, 
V.Chazov, I.  Gorbunov, D.Zimnukhov, D.Kuvshinov, P.Balanutsa, V.Vladimirov, 
Lomonosov Moscow State University,SAI

Ioffe Institute, Sankt Petersburg

D. Buckley,
South African Astronomical Observatory (SAAO)

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

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

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

Instituto de Ciencias Astronomicas, de la Tierra y del Espacio (ICATE)

O. Gres, N.M.Budnev , Yu.Ishmuhametova
Irkutsk State University (ISU)

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

MASTER-SAAO robotic telescope (MASTER-Net:, 
Lipunov et al., 2010, Advances in Astronomy, vol. 2010, 30L) located in 
South Africa (South African Astronomical Observatory) was pointed to the 
GRB180723.76 198 sec after notice time and 767 sec after trigger time at 
2018-07-23 18:22:35 UT (see Fermi GBM trgger number 554062193). 
On our first 
(150s exposure)  set we haven`t found  optical transient  within FERMI 
error-box (ra=7.83333 dec=-66.1097 r=1).
The 5-sigma upper limit has been about 17.5 mag

There is no OT brighter 19.2  mag found on stacked images.

The coverage  map of the 3 sigms + sigma error box is available at

The observations made on zenit distance = 74 degrees under strong wind, 
galaxy latitude b = -51 degree.
The moon (86 % bright part) is 69 degrees above the horizon. The distance 
between  moon and  object is 82
The sun  altitude  is -31.3 degree.
The object  observed till sunrise at 2018-07-24 05:30:53 UT.

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