GCN Circular 14710
Subject
GRB 130527A: NOT optical counterpart
Date
2013-05-28T16:42:36Z (12 years ago)
From
Daniele Malesani at Dark Cosmology Centre, Niels Bohr Inst <malesani@dark-cosmology.dk>
Z. Cano (U. Iceland), D. Malesani (DARK), N. R. Tanvir (U. Leicester),
D. Xu (DARK/NBI), T. Kangas (U. Turku), and J. Kajava (NOT) report on
behalf of a larger collaboration:
On 2013 May 28, beginning at 03:55 UT, we observed the field of GRB
130527A (Gompertz et al., GCN 14703) with the Nordic Optical Telescope
(NOT) equipped with the ALFOSC instrument using the z filter, for a
total exposure time of 40 minutes. Observations were carried out at
moderate airmass, with the bright Moon only 18 deg away, at a mean epoch
of May 28.179 UT (13.94 hr after the GRB).
Inside the refined XRT error circle (Evans et al., GCN 14705; see also
http://www.swift.ac.uk/xrt_positions/) we do not detect any bright
source, but there is a faint, apparently extended object with magnitude
z = 21.4 +- 0.2. The limiting magnitude for an isolated object in our
coadded image is z = 22.1. Calibration has been derived using two stars
in the USNO B1 catalog (0652-0853265 and 0652-0853288), and converting
their R2 and I magnitudes into z using the transformation equations from
Jordi et al. (2006, A&A, 460, 339). The source could be the GRB host.
A snapshot showing our coadded image can be found at the URL
http://www.astro.ku.dk/~malesani/GRB/130527A/GRB130527A_finder_NOT.jpg