TITLE:   GCN CIRCULAR
NUMBER:  22870
SUBJECT: GRB 180626A: TSHAO optical upper limit
DATE:    18/06/29 16:09:33 GMT
FROM:    Alexei Pozanenko at IKI, Moscow  <apozanen@iki.rssi.ru>

E. Mazaeva (IKI), A. Pozanenko (IKI),  A. Kusakin (FAPHI), I. Reva 
(FAPHI),  A. Volnova (IKI), M. Krugov (FAPHI) report on behalf of larger 
GRB follow-up collaboration:

We observed the field of GRB 180626A  (Evans et al., GCN 22850; Gotz  et 
al., GCN 22851)   with Zeiss-1000 1-m telescope of Tien Shan 
Astronomical Observatory starting on June 26 (UT) 16:26:21. We obtained 
several images in R-filter.  The optical afterglow (Evans et al., GCN 
22850;  Martone et al. GCN 22854; Troja et al. GCN 22855; Watson et al. 
GCN 22859)  is not detected in a stacked image. Preliminary photometry 
of the field is following.

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

2018-06-26  16:26:21 0.41918  R      99*120  n/d  n/d    21.5

The photometry is based on several nearby SDSS-DR10 stars.

Ref.stars
SDSS-DR9_id            R(Lupton)
J161422.32+144433.2    15.113
J161357.84+144752.0    13.989
J161440.94+144745.0    13.136