TITLE:   GCN CIRCULAR
NUMBER:  18182
SUBJECT: GRB 150818A: Mondy optical observations
DATE:    15/08/20 17:24:54 GMT
FROM:    Alexei Pozanenko at IKI, Moscow  <apozanen@iki.rssi.ru>

E. Mazaeva (IKI), E. Klunko (ISTP), A. Volnova (IKI), I. Korobtsev  (ISTP), 
A. Pozanenko (IKI) report on behalf of larger GRB follow-up  collaboration:

We continue observations of  the of Swift GRB 150818A (D'Elia et al., GCNC 
18152) with AZT-33IK telescope of Sayan observatory (Mondy).   We obtained 
several images in R-filter   starting on Aug., 19 (UT) 15:33:10.  The 
optical transient (Marshall et al., GCN 18155; McCauley et al., GCN 18161; 
Schulze  et al., GCN 18164; Mazaeva et al., GCN 18175) is clearly visible. 
Preliminary photometry of the optical transient is following

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

2015-08-19  15:33:10   1.18517  R        30*120  21.0 0.1

Photometry is based on USNO-B1.0 stars referenced in (Mazaeva et al., GCN 
18175)