[vsnet-grb-info 18466] GRB 160910A: Global MASTER Net OT detection before LAT alert

[GCN Circulars]

TITLE:   GCN CIRCULAR
NUMBER:  19914
SUBJECT: GRB 160910A: Global MASTER Net OT detection before LAT alert
DATE:    16/09/12 19:16:03 GMT
FROM:    Vladimir Lipunov at Moscow State U/Krylov Obs  <lipunov at xray.sai.msu.ru>

V. Lipunov, E. Gorbovskoy, N.Tyurina, V.Kornilov,
P.Balanutsa, A.Kuznetsov, D.Kuvshinov
Lomonosov Moscow State University, Sternberg Astronomical Institute

D.Buckley, S. Potter, A.Kniazev, M.Kotze
South African Astronomical Observatory

R. Rebolo, M. Serra Ricart, N. Lodieu, G. Israelian
The Instituto de Astrofisica de Canarias

K.Ivanov, O.Gres, N.M.Budnev, S.Yazev,
Irkutsk State University

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

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

Hugo Levato, Carlos Saffe
Instituto de Ciencias Astronomicas, de la Tierra y del Espacio (ICATE)

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


MASTER-SAAO  robotic telescope (MASTER-Net: http://observ.pereplet.ru) 
located in SAAO was pointed to the FERMI GBM  GRB160910.72 15 sec after 
notice time and 65 sec after trigger time at 2016-09-10 17:20:45 UT.

On our first (20s exposure started 75 sec after GBM trigger)  set we do 
not found  optical transient within  FERMI error-box (ra=14 54 00 
dec=+39 23 00 r=3.41, trigger 495220783 / 160910722
(Veres  and  C.Meegan, GCN 19901)) because very low 
altitude on horizont ~3 degrees (one tube was under the roof).

Fortunatelly, we saw OT by one of two MASTER Very Wide Field Cameras (5 
sec expositon, 0.25 sec readout) .
On MASTER-SAAO VWF Camera  we see OT at 3 sigma confidence level with 
magnitude 11.6 +- 0.5 mag on a co-added images with total exposure 95 
seconds  (19 x 5 sec) starting at 17:20:45 i.e. 65 sec after trigger time. Mean 
time is 113 sec after trigger.

On our second MASTER-SAAO (30s 
exposure)  set started at 2016-09-10 17:22:26 (167 sec after trigger time) 
we  found OT  within FERMI error-box  with unfileterd
magnitide m = 11.6+-0.1 . The second exposition was making after receiving 
new Fermi GBM coordinates.

Ra, Dec  =  14h 45m 46.03s   +39d 04m 00.52s
err = +-0.5 arcsec

(cf.  A. D'A. et al., GCN 19904; A. de Ugarte Postigo et al., 19907; 
Malesani et al., GCN 19908 )

MASTER-IAC  robotic telescope (MASTER-Net: http://observ.pereplet.ru) 
located in IAC was starting survey on the FERMI GBM  GRB160910.72 
error-box  (ra=14 46 14 dec=+39 25 10 r=1.0)  11142 sec after notice time 
and 11239 sec after trigger time at 2016-09-10 20:26:58 UT. The 5-sigma upper 
limit on our first (60s exposure)  set is about 18.3 mag .  The OT 
unfiltered magnitude is 17.4+-0.4 .


The light curve is available at
http://master.sai.msu.ru/static/GRB160910A.png


The MASTER-SAAO power law index  alpha  = 1.30+-0.07 ( I ~ t^-alpha) in 
agreement with MASTER-IAC and some 
contradiction with late point (Malesani  et al., GCN 19908 )

The MASTER-SAAO and NOT combined   power law index  alpha  = 
1.17+-0.02 .


All MASTER observations was done  before LAT alert.


The message may be cited.