[vsnet-grb-info 12445] GRB 120923A: optical upper limit

[GCN Circulars]

TITLE:   GCN CIRCULAR
NUMBER:  13820
SUBJECT: GRB 120923A: optical upper limit
DATE:    12/09/26 20:24:47 GMT
FROM:    Alexei Pozanenko at IKI, Moscow  <apozanen at iki.rssi.ru>

L. Elenin (KIAM), A. Volnova (SAI MSU, IKI), I. Molotov (KIAM), A. Pozanenko 
(IKI) report on behalf of  larger GRB  follow-up collaboration:

We observed the field of  the Swift GRB 120923A (Yershov  et al., GCN 13796) 
with 0.45-m telescope of ISON-NM observatory  starting on  Sep. 23 (UT) 
05:18:58, i.e 172 s after burst trigger.  We took  several unfiltered images 
of 30 s and 60 s exposures.  We do not detect the optical counterpart (Levan 
et al., GCN 13802). A  photometry of  co-added frames is based  on the 
USNO-B1.0 (R2)  nearby  stars is following:

  T0+,          Exposure,  OT,         UL (3 sigma)
  mid, d         (s)

0.00447      9x30           n/d           19.7
0.02839    53x30           n/d           20.5