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GCN Circular 16728

GRB 140818B: ISON-Kislovodsk and ISON-Burakan optical upper limit
2014-08-20T14:50:32Z (10 years ago)
Alexei Pozanenko at IKI, Moscow <>
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
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