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GCN Circular 16780

Subject

GRB 140818B: TShAO optical upper limit

Date

2014-09-05T06:16:20Z (10 years ago)

From

Alexei Pozanenko at IKI <alex@grb.rssi.ru>

A. Pozanenko (IKI), I. Rewa, W. Mundrzyjewski, A. Kusakin (Fesenkov Astrophysical Institute), A. Volnova (IKI),  report on behalf of larger GRB follow-up collaboration:

We observed the field of the Swift GRB 140818B  (Vargas et al., GCN 16709Not found
 
 
)with Zeiss-1000 (East) telescope of Tien Shan Astronomical Observatory starting on Aug. 19, (UT) 17:05. We took several images in R-filter.  Within enhanced XRT error circle  (Beardmore et al., GCN 16712Not found
 
 
) we do not detect the afterlow (Aceituno et al., GCN 16711Not found
 
 
; Knust et al., GCN 16713Not found
 
 
). The source mentioned by Knust et al. (GCN 16713Not found
 
 
) is clearly visible in a stacked image in coordinates (J2000) 18:04:32.76 -01:23:08.9 (uncertainty  is 0.2 arcsec in both coordinates)  and has brightness of R=22.1+/-0.1.

Details of a photometry of the stacked image are following

Date       UT start  t-T0,d  Exp,s   Filter Up_Lim (3 sigma)
                     (mid)

2014-08-19 16:11:12  0.9317  20*600  R      22.9


The photometry is based on nearby USNO-B1.0 stars, R2 magnitudes.