[vsnet-grb-info 11100] GRB 111029A: SAO RAS optical limits

[GCN Circulars]

TITLE:   GCN CIRCULAR
NUMBER:  12515
SUBJECT: GRB 111029A: SAO RAS optical limits
DATE:    11/10/31 18:53:30 GMT
FROM:    Vladimir Sokolov at SAO RAS  <sokolov at sao.ru>

A. S. Moskvitin and V. V. Sokolov report on behalf of larger collaboration:

The field of GRB 111029A (Troja et al., GCN#12498) was observed
with the Zeiss-1000 telescope of SAO RAS (Russia) on October 29/30 night.
12 x 300 sec. in Rc and 12 x 300 sec. in Ic images were obtained
under the good conditions and the seeing 2" (FWHM of stellar-like objects
at the co-added images). The observation started at 21:31:21 October 29
(since 11.8 hours after the trigger), finished at 00:33:51 October, 30 UT.

No optical counterpart was detected within the XRT 1".9 error circle
(according to http://www.swift.ac.uk/xrt_positions/ ) up to the 3 sigma
limiting magnitudes R_lim = 24.6 and I_lim = 23.3. The calibration was done
against R2 and I magnitudes of nearby USNO B-1.0 stars. The Rc and Ic images
can be found at ftp://ftp.sao.ru/pub/grb/GRB111029A/GRB111029A.jpg

The closest object is located 4".65 South-West from the center of XRT
error circle. The brightness of this object is R = 22.99 +/- 0.32,
I = 21.79 +/- 0.28 (the high error is due to calibration) and the
coordinates are R.A.(J2000) = 02:59:07.71, Dec.(J2000) = +57:06:35.5,
with the uncertainty 0".21. Due to cosmological nature of GRBs
this object probably can not be related to the GRB 111029A.