[vsnet-grb-info 15439] GRB 140818B: ISON-Kislovodsk and ISON-Burakan optical upper limit

[GCN Circulars]

TITLE:   GCN CIRCULAR
NUMBER:  16728
SUBJECT: GRB 140818B:  ISON-Kislovodsk and ISON-Burakan optical upper limit
DATE:    14/08/20 14:50:32 GMT
FROM:    Alexei Pozanenko at IKI, Moscow  <apozanen at iki.rssi.ru>

A. Pozanenko (IKI), E. Romas (ISON), V. Nevskiy (ISON), G. Ohanian 
(Byurakan Astrophisical Observatory), H. Andreasyan (Byurakan 
Astrophisical Observatory), A. Volnova (IKI),  I. Molotov (KIAM), 
report on  behalf of larger collaboration:

We observed the field of  GRB 140818B (Vargas et al., GCN 16709) with 
Santel-400AN   telescope of ISON-Kislovodsk observatory starting on (UT) 
18:54:36 and ISON-Burakan ORI-40 starting on (UT) 18:55:08. In the 
enhanced XRT position (Beardmore et al., GCN 16712)   we do not detect 
optical afterglow candidate (Aceituno et al., GCN 16711; Knust et al., 
GCN 16713) neither in the first image nor in the stacked images. 
Preliminary photometry is based on nearby USNO-B1.0 stars, R2 magnitudes:


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

2014-08-18 18:54:36  0.0198   None    7*100   19.0        Kislovodsk

2014-08-18 18:55:08  0.0174   None    21*60   18.5        Burakan