[vsnet-grb-info 21146] GRB 180914B: MASTER OT automatic dtection

[GCN Circulars]

TITLE:   GCN CIRCULAR
NUMBER:  23245
SUBJECT: GRB 180914B: MASTER OT automatic dtection 
DATE:    18/09/17 11:10:54 GMT
FROM:    Vladimir Lipunov at Moscow State U/Krylov Obs  <lipunov at xray.sai.msu.ru>

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.Svinkin (Ioffe Institute, Sankt Petersburg)

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

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)

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-Tunka robotic telescope (MASTER-Net: http://observ.pereplet.ru, 
Lipunov et al., 2010, Advances in Astronomy, vol. 2010, 30L) located in 
Tunka Astrophysical Center (Baykal Lake,  Applied Physics Institute, 
Irkutsk State University, Russia)  was starting 
survey on the LAT  GRB180914.77 error-box (ra=22 09 47 dec=+24 52 47 
r=0.33)  9409 sec after notice time and 79012 sec after trigger time at 
2018-09-15 16:19:55 UT. The 5-sigma upper limit on our first (180s 
exposure)  set is about 19.7 mag

MASTER OT J220925.53+250343.3  - Afterglow

MASTER-Tunka auto-detection system discovered OT source at (RA, Dec) = 22h 
09m 25.53s +25d 03m 43.3s on 2018-09-15 16:19:55.393UT. Error is 0.7 
arcsec. This position is coincident with late XRT (P. A. Evans, GCN 23234) 
and KAIT  (WeiKang Zheng and Alexei V.  Filippenko, GCN 23237) positions. 
The OT magnitude in clear filter is 19.2m (limit 19.7m).
This is the first optical magnitude ( see also Eleonora Troja GCN 23238, 
A. de Ugarte Postigo et al., GCN 23239; N. Paul M. Kuin et al., GCN 23241; 
Eleonora Troja et al., GCN 23243).

The OT is seen in 2 images. There is no minor planet at this place.

We have reference image without OT on 2011-12-15.46200 UT with unfiltered 
magnitude limit 20.0m.

The discovery and refernces images are available at
http://master.sai.msu.ru/static/OT/MASTEROTJ220925.53+250343.3.jpg

The galactic latitude b = -25 deg.

The observations made on zenit distance = 28 deg.The moon (38 % bright 
part) below the horizon (The altitude of the Moon is -17 deg. ).
The sun  altitude  is -34.5 deg.
The object can be observed till sunrise at 2018-09-15 22:42:06