[vsnet-grb-info 18488] GRB 160917A: Mondy afterglow confirmation

[GCN Circulars]

TITLE:   GCN CIRCULAR
NUMBER:  19936
SUBJECT: GRB 160917A: Mondy afterglow confirmation
DATE:    16/09/19 20:12:31 GMT
FROM:    Alexei Pozanenko at IKI, Moscow  <apozanen at iki.rssi.ru>

A. Volnova (IKI), A. Pozanenko (IKI), E. Klunko (ISTP), E. Mazaeva 
(IKI), I. Korobtsev (ISTP)  report on behalf of larger GRB follow-up 
collaboration:

We observed the field of the GRB 160917A (Racusin et al. GCN 19926) with 
  AZT-33IK telescope of Sayan observatory (Mondy) starting on Sep., 18 
(UT) 15:25:21. We obtained several images in R-filter. We do not detect 
the optical source reported as afterglow candidate (Volnova et al. GCN 
19929; Kuin  et al. GCN  19931). Preliminary photometry of the field is 
following

Date        UT start   t-T0      Filter Exp.   OT     UL (3 sigma)
                        (mid, days)       (s)

2016-09-18  15:25:21   1.18522    R     60*60  n/d    22.0

Photometry is based on nearby USNO-B1.0 stars used in GCN circ. 19929.
In comparison with our previous observation (Volnova et al. GCN 19929) 
the source is not visible  up to 22.0 mag. The source faded between two 
epochs on at least  1.4 magnitudes and it is most probably the afterglow 
of GRB 160917A. Our observation is compatible with more deep RATIR 
observation in r-filter (Butler et al. GCN 19933).