[vsnet-grb-info 19454] GRB 170531B: CrAO confirmation of the afterglow

[GCN Circulars]

TITLE:   GCN CIRCULAR
NUMBER:  21174
SUBJECT: GRB 170531B:  CrAO confirmation of the afterglow
DATE:    17/06/01 00:11:21 GMT
FROM:    Alexei Pozanenko at IKI, Moscow  <apozanen at iki.rssi.ru>

A. Pozanenko (IKI), D. Chestnov (ISON), A. Novichonok (ISON), A. Mokhnatkin 
(ISON)   report on behalf of larger GRB follow-up collaboration:

We observed the field of the GRB 170531B (Evans et al.,GCN  21171) with 
with Zeiss-1000/Koshka telescope  starting on May 31 (UT) 22:32:32, i.e. ~30 
minutes after burst onset.  We took several images in  filter R with 
exposures of 180 s. Near the border of XRT error circle (Evans et al.,GCN 
21171)  we  detect the source in coordinates (J2000) 19:07:31.67 -16:25:09.3 
with uncertainity of 0.5 arcsec in both coordinates. The source is probably 
coincedent with the object reported by (Lipunov et al., GCN  21172). The 
source is fading from R=19.1 at (UT) 22:32:32 down to R=19.5 at  (UT) 
23:30:56. Most probably the source is an afterglow of  GRB 170531B.