[vsnet-grb-info 12618] GRB 121117A: optical upper limit

[GCN Circulars]

TITLE:   GCN CIRCULAR
NUMBER:  13978
SUBJECT: GRB 121117A: optical upper limit
DATE:    12/11/21 07:21:38 GMT
FROM:    Alexei Pozanenko at IKI, Moscow  <apozanen at iki.rssi.ru>

A. Volnova (SAI MSU, IKI), D.Varda (ISON), E.Sinyakov (ISON), I. Molotov 
(KIAM), A. Pozanenko (IKI) report on behalf of larger GRB follow-up 
collaboration:

We observed the field of GRB 121117A (Cummings et al., GCN 13967) with 
ORI-25 telescope of ISON-Blagoveshensk observatory starting on Nov.17 
(UT) 09:05:39. We took several unfiltered exposures within 2 hours after 
the start. We do not detect the OT (Oates et al., GCN 13973) in the XRT 
error circle (Beardmore et al. GCN 13972) in any stacked images. A 
photometry is based on nearby USNO-B1.0 stars (R2):


T_start   T0+,    Filter, exposure, UL (3 sigma)
(UT)      mid (d)         (s)

09:05:39  0.03105 none    80 x 40   18.3
10:05:44  0.07483 none    88 x 40   18.4
09:05:39  0.05397 none   168 x 40   18.9