[vsnet-grb-info 15823] GRB 141121A: Mondy optical observations

[GCN Circulars]

TITLE:   GCN CIRCULAR
NUMBER:  17111
SUBJECT: GRB 141121A: Mondy optical observations
DATE:    14/11/28 19:21:59 GMT
FROM:    Alexei Pozanenko at IKI, Moscow  <apozanen at iki.rssi.ru>

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

We observed the field of GRB 141121A (Lien et al., GCN 17075) with 
AZT-33IK telescope of Sayan observatory (Mondy) on Nov., 27  starting 
(UT) 19:13:37.  We obtained several  images in R-filter ander favorable 
weather and mean FWHM of 1.8 arcsec. In a combined image we clearly 
detect optical  afterglow (Tanga et al., GCN 17078; Perley et al., GCN 
17081). We do not detect the nearby source reported in (Watson et al., 
GCN 17075). Instead of we detect a Source (possible host?) 3 arcsec to 
the West from OT. The Source is absent in SDSS DR9. Coordinates of the 
OT and the Source are

OT
(J2000)
08 10 40.55 +22 13 03.0
with accuracy of  0.4" in both coordinates

The Source to the West
(J2000)
08 10 40.35 +22 13 03.0
with accuracy of  0.5" in both coordinates

Astrometry solutions are based on USON-B1.0 catalog.

A preliminary photometry of the OT is based on nearby SDSS  stars:

date       UT start   t-T0     Filter   Exp.    OT    OT_err
                       (mid, days)       (s)

2014-11-27 19:13:37   6.6923   R        72*120  21.57 0.05

And preliminary photometry of the Source is R 22.95 ± 0.11.
The source is barely visible in our earlier observations (Mazaeva et 
al., GCN 17102) and photometry of the early observation reported in 
(Mazaeva et al., GCN 17102) might be biased of this Source.

The finding chart can be found in
http://grb.rssi.ru/GRB141121A/GRB141121A.Mondy_host_chart.png