TITLE:   GCN CIRCULAR
NUMBER:  19862
SUBJECT: GRB 160824A: ISON/Terskol optical observations
DATE:    16/08/25 18:20:16 GMT
FROM:    Alexei Pozanenko at IKI, Moscow  <apozanen@iki.rssi.ru>

E. Mazaeva (IKI), A. Mokhnatkin (KIAM),  A. Volnova (IKI), Molotov (KIAM), 
A. Pozanenko  (IKI) report on behalf of larger GRB follow-up collaboration

We observed the field of GRB 160824A (Evans   et al., GCN 19855)  with K-800 
(0.8m f/2.9)   telescope  of ISON/Terskol   observatory. We obtained several 
unfiltered images starting on  August 24 (UT) 23:58:36.  We detected 
optical source in coordinates
(J2000) 05:20:21.18 +40:01:43.5 with uncertainty of 1 arcsec in both 
coordinates. This is 2.6 arcsec apart of the center of the enhanced XRT 
error circle (Goad et al., GCN 19857).  At this time we cannot say nothing 
about variability of the object.  It is not clear whether our source is the 
same as the source reported by Marshall et al. (GCN 19860).  Preliminary 
photometry of a combined image is following

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

2016-08-24 23:58:36 0.02758 CR      400    20.6   0.3  20.9

Photometry is based on nearby USNO-B1.0 stars
USNO-B1.0_id    R2
1300-0122742    18.17
1300-0122665    18.04
1300-0122653    18.66
1300-0122680    17.00
1300-0122864    17.60
1299-0128308    18.00
1300-0122784    17.56