TITLE:   GCN CIRCULAR
NUMBER:  12025
SUBJECT: GRB 110520A - NOT optical observation
DATE:    11/05/21 01:13:53 GMT
FROM:    Steve Schulse at U. of Iceland  <steve@raunvis.hi.is>

S. Schulze (U. Iceland), D. Xu (WIS), D. Malesani (DARK/NBI), P.  
Jakobsson (U. Iceland),
S. Asadi, A. Barekat, L. Guaita, I. A. Gumus, S. Lindgren,  J.  
Lindkvist, K. Migotto, A. Razza,
T. Str�m, F. Taddia, G. Olofsson (Stockholm Observatory), report on  
behalf of a larger
collaboration:

We observed the field of GRB 110520A (De Pasquale et al., GCN 12020)  
with the
Nordic Opitcal Telescope (NOT) equipped with ALFOSC. We obtained 3x600 s
R-band and 6x300 s I-band images. Observations started at 21:19:16.9 UT
on May 20 (i.e., 0.8414 hr after the burst).

An optical source is clearly detected in each of the stacked R-band  
and I-band images
at coordinates

RA(J2000)  = 08:57:21.84
Dec(J2000) = +56:25:40.2
Error-radius: ~0.1 arcsec

which is 2.7 arcsec away of the XRT position center reported at
http://www.swift.ac.uk/sper/index.php.

This source has R~23.7 mag at a median time 1.118 hrs post-burst,  
calibrated with the
#1464-0205280 star (R1=18.97, R2=18.92) in the USNO B1 catalog. At the  
moment
our data does not allow to test for variability of the source.