TITLE:   GCN CIRCULAR
NUMBER:  22978
SUBJECT: GRB 180715A: MASTER optical observation 
DATE:    18/07/20 18:09:52 GMT
FROM:    Vladimir Lipunov at Moscow State U/Krylov Obs  <lipunov@xray.sai.msu.ru>

D. Vlasenko, N.Tiurina,  E. Gorbovskoy, V. Lipunov, V.Kornilov, A.Kuznetsov, 
V.Chazov, I.  Gorbunov, D.Zimnukhov, D.Kuvshinov, P.Balanutsa, V.Vladimirov
Lomonosov Moscow State University,SAI
4
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)

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)


MASTER-Tavrida robotic telescope (MASTER-Net: http://observ.pereplet.ru, 
Lipunov et al., 2010, Advances in Astronomy, vol. 2010, 30L) located in 
Russia (SAI Crimea astronomical station) was pointed to the GRB180715A 
(Ukwatta et al., GCN Circ #22947) 96 sec after trigger time at 2018-07-15 
18:08:41 UT as sun altitude was -6.95 dec first image was at 2018-07-15 
18:30:37.  On our first (180s exposure)  set we do not found  optical 
transients within Swift error-box (ra=235.069 dec=-0.925 r=0.05)  brighter 
then 20.7.

The observations made on zenit distance = 44.16 degrees, galaxy latitude b 
= 40,1 degree.
The moon (10 % bright part) is 8 degrees above the horizon. The distance 
between  moon and  object is 82
The sun  altitude  is -9.85 degree.
The object can be observed till 2018-07-15 21:36:28

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 pointed to the 
GRB180715A (Ukwatta et al., GCN Circ #22947) 495 sec after trigger time at 
2018-07-15 18:15:20 UT . On our first (100s exposure)  set we  do not 
found  optical transients within Swift error-box (ra=235.069 dec=-0.925 
r=0.05)  brighter then 20.8.

The observations made on zenit distance = 57.43 degrees, galaxy latitude b 
= 40.1 degree.
The moon (10 % bright part) is 6.5 degrees above the horizon. The distance 
between  moon and  object is 83
The sun  altitude  is -28.83 degree.
The object can be observed till 2018-07-15 22:48:22.

The visibility GRB error box (coord: 235.069 -0.925  error_box: 0.05) at 
trigger time at different MASTER sites:

obj:  44.19 sun: -6.73 - Tavrida (Crimea, Russia)
obj:  36.94 sun:  23.52 - IAC, Teide (Tenerife,Spain)
obj:  57.43 sun: -28.83 - SAAO (Sutherland, SA)
obj:  43.89 sun: -11.87 - Kislovodsk (Russia)
obj:  27.30 sun: -7.55 - Ural (Kourovka, Russia)
obj:  9.49  sun: -15.74 - Tunka (near Baykal Lake, Russia)
obj: -5.64  sun: -10.73 - Amur(Blagoveschensk)
obj: -7.22  sun:  32.97 - OAFA (Argentina)

The message may be cited.