GCN Circular 23050

V. Lipunov, E. Gorbovskoy, N.Tiurina, D.Vlasenko, V.Kornilov, A.Kuznetsov, 
V.Chazov, I.  Gorbunov, D.Zimnukhov, D.Kuvshinov, P.Balanutsa,
V.Vladimirov,
Lomonosov Moscow State University,SAI

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)

H.Levato,
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: http://observ.pereplet.ru, Lipunov 
et al., 2010, Advances in Astronomy, vol. 2010, 30L) located in South Africa 
(South African Astronomical Observatory) was detected new optical 
object (Lipunov et al., GCN Circ #23048) MASTER OT J165415.75-540239.27
at Swift XRT position (Starling et al., GCN
#23046; Perri et al., GCN #23049;):

RA, DEC = 16h 54m 15.75s , -54d 02m 39.27s
Error ~1 arcsec

We see a gradual attenuation of the OT on an automatic light 
curve. Thus, the transient is an optical counterpart of the gamma-ray 
burst GRB 180728A.

The automatic light curve is available at 
http://observ.pereplet.ru/images/MASTER_OT_J165415.75-540239.27.jpg


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