[vsnet-grb-info 16908] GRB 150818A: continued Mondy optical observations

[GCN Circulars]

TITLE:   GCN CIRCULAR
NUMBER:  18189
SUBJECT: GRB 150818A: continued Mondy optical observations
DATE:    15/08/21 15:39:24 GMT
FROM:    Alexei Pozanenko at IKI, Moscow  <apozanen at 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., 20 (UT) 
16:54:32.  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)

2015-08-20 16:54:32   2.23334  R        15*120  21.15 0.09

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

The continued shallow decay mentioned in Schulze et al. (GCN 18179) 
indeed can be explained by underlying host galaxy (Sanchez-Ramirez et 
al., GCN 18177).