GRB 180806.94

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

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

D. Buckley,
South African Astronomical Observatory (SAAO)

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-IAC robotic telescope (MASTER-Net: http://observ.pereplet.ru, 
Lipunov et al., 2010, Advances in Astronomy, vol. 2010, 30L) located in 
Spain (IAC Teide Observatory) was pointed to the  GRB180806.94 (GBM 
trigger 555287944) 77 sec 
after notice time and 122 sec after trigger time at 2018-08-06 22:41:02 
UT.

The observations made on zenit distance = 78 deg., galactic latitude b 
= -36 deg. The moon (27 % bright part) below the horizon (The altitude of 
the Moon is -36 deg ). The sun  altitude  is -32.4 deg.
The object can be observed till sunrise at 2018-08-07 06:29:57 UT.

We found  OT inside 3 sigma Fermi GBM error box.
The Cover Map is available at
http://master.sai.msu.ru/static/OT/MASTERmapFermi555287944.jpg


MASTER OT J004613.05+242014.1 discovery

MASTER-IAC auto-detection system discovered OT source at
(RA, Dec) = 00h  46m 13.05s +24d 20m 14.1s  109.3 min after trigger on 
2018-08-07  00:28:20.467 UT .

The OT unfiltered magnitude is 17.0m (limit 17.9m).

The OT is seen in 4 images. There is no minor planet at this place.

We have reference image without OT on 2016-10-05.08846 UT with unfiltered 
magnitude limit 20.2m.

There is no USNO-B1 sources, it means 22mag limit in history and more then 
5m amplitude of current outburst.
There is Sloan star in 2.9"

Spectral observations are required.

The discovery and reference images are available at:

http://master.sai.msu.ru/static/OT/004613.05242014.1.png



This message can be cited.

[GCN OPS NOTE(07aug18): Per admin, the double use of "GRB" in the 
Subject-line was removed; from "GRB GRB180806.94" to "GRB 180806.94".]

Alan M. Watson (UNAM), Nat Butler (ASU), Rosa L. Becerra (UNAM), William
H. Lee (UNAM), Carlos Rom��n-Z����iga (UNAM), Alexander Kutyrev (GSFC), and
Eleonora Troja (GSFC) report:

We observed the field of the OT MASTER OT J004613.05+242014.1 (Lipunov
et al., GCN Circ. 23091
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 ) possibly associated with GRB 180806.94 (Fermi
trigger 555287944) with the COATLI 50-cm telescope and interim imager at
the Observatorio Astron��mico Nacional on the Sierra de San Pedro M��rtir
(http://coatli.astroscu.unam.mx) from 2018-08-07 11:23:26 UTC to
11:52:11 UTC, obtaining a total of 1440 seconds of exposure in the w
filter.

We detect a source coincident with the reported coordinates of the OT
(Lipunov et al., GCN Circ. 23091
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 ), and preliminary photometry suggests

w = 20.0 +/- 0.2

This magnitude is calibrated against the USNO-B1 catalog (adjusted to an
approximate AB system) and is not corrected for Galactic extinction in
the direction of the GRB.

Our observations would appear to show fading compared to the unfiltered
magnitude of 17.0 reported by Lipunov et al. (GCN Circ. 23091
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 ).

We thank the COATLI technical team (Fernando ��ngeles, Oscar Chapa,
Salvador Cuevas, Alejandro Farah, Jorge Fuentes, Rosal��a Langarica,
Fernando Quir��s, and Carlos Tejada) and the staff of the Observatorio
Astron��mico Nacional.

We thank Vladimir Lipunov for bringing this observation to our attention.