GCN Circular 15394
Subject
Swift 575905/GRB 131026A: optical observations
Date
2013-10-28T17:52:28Z (11 years ago)
From
Alexei Pozanenko at IKI, Moscow <apozanen@iki.rssi.ru>
A. Volnova (IKI), R. Inasaridze (AAO), G. Inasaridze (AAO), V.
Zhuzhunadze (AAO), Yu. Krugly (IA KhNU), I. Molotov (KIAM), A. Pozanenko
(IKI) report on behalf of larger GRB follow-up collaboration:
We observed the field of Swift Trigger 575905/GRB 131026A (Cenko et al.,
GCN 15384) with AS-32 telescope of Abastumani Observatory starting
Oct., 26 (UT) 21:06:35. We obtained several unfiltered images with
exposures of 180 s. We investigated stacked image and found that both
XRT sources (Izzo et al., GCN 15388) coincide with known optical
sources, i.e.
source 1 (XRT) = SDSS J010222.74+323005.0 (01:02:22.75 +32:30:05.0)
source 2 (XRT) = TYC 2281-1221-1 (01 02 02.468 +32 30 01.53)
Within BAT error circle (Cenko et al., GCN 15384) we found a point-like
source which is not presented in SDSS catalog. Coordinates of the source
are (J2000) RA= 01 02 14.64, Dec = +32 30 35.7 with uncertainties of
0.2 arcsec in both coordinates. The details of the photometry of the
source are the following:
UT start t-T0 Filter Exp. OT UL (3 sigma)
(mid, days) (s)
21:06:35 0.64270 None 32x180 21.67 +/- 0.08 22.6
The photometry is based SDSS stars, R (gri -> R transformations by
Lupton 2005):
SDSS id R(Lupton)
J010212.32+323137.9 18.988
J010208.62+323107.7 17.448
J010155.76+322851.8 17.317
We subdivide total number of images in two combined images and compare
astrometry and photometry of the two combined images. One can conclude
that the upper limit of a proper motion of the source is 3 arcsec per 50
minutes, and one can marginally suggest that brightness of the source is
increased at ~0.3m between the two combined images.
Finding chart can be found in
http://grb.rssi.ru/GRB131026A_Swift_575905/GRB131026A_chart2.png
Additional observations in optic and X-ray are encouraged.