[vsnet-grb-info 13927] GRB 130903A: optical observations

[GCN Circulars]

TITLE:   GCN CIRCULAR
NUMBER:  15241
SUBJECT: GRB 130903A: optical observations
DATE:    13/09/21 19:07:58 GMT
FROM:    Alexei Pozanenko at IKI, Moscow  <apozanen at iki.rssi.ru>

A. Volnova (IKI),  V. Nevskiy (ISON),  I. Molotov (KIAM), Yu. Krugly(IA 
KhNU), I. Slyusarev (IA KhNU), A. Pozanenko (IKI)  report on behalf of 
larger collaboration:

After the refined analysis of the ISON-Kislovodsk observations (Volnova 
et al., GCN 15171) of GRB 130903A field (Mereghetti et al., GCN 15169) 
in the coordinates of OT reported by Tanga et al. (GCN 15177) we found a 
faint source with a R magnitude 20.40 ± 0.3. Photometry is  based on the 
  stars reported below.

We also observed the field of the field with AZT-8 (0.7m) telescope of 
Institute of Astronomy, Kharkiv National University starting on Sep. 03 
(UT) 01:38:52. We took 11 frames with exposures of 120 seconds in R 
filter. On the stacked image within 1.5 arcmin of error circle 
localization (Mereghetti et al., GCN 15169) we do not detect any
source.

Photometry of combined image is the following

T_start, T0+,    Exp.,  Filter, UL (3 sigma)
(UT) mid (d)     (s)

01:38:52 0.03579 11*120 R       >20.0

and based on SDSS stars, R (gri -> R transformations by Lupton 2005):

# SDSS R Err_R
1 J052835.34-000624.7 15.543 0.013
2 J052817.12-000749.0 14.650 0.012
3 J052841.64-000642.3 14.233 0.013