GCN Circular 209

GRB990123 Optical Observation at SAO-RAS

V. Sokolov, S. Zharikov (SAO-RAS) and L. Nicastro, M. Feroci, E. Palazzi
on behalf of the BeppoSAX team report:

We obtained an R-band image of the BeppoSAX localization of GRB990123
on 1999 Jan 24.076 UT, 16.04 hours after the GRB event, with the SAO-RAS
6-m telescope.  The weather was cloudy.
In spite of that, in a 15-min exposure image we were able to see an
object at the position of the optical candidate suggested by Odewahn et al.
(GCN #201
Not found
 
 
).  We estimated a magnitude of 19.6 +/- 0.2 (using star 1 from
GCN #204
Not found
 
 
) and 19.9 +/- 0.2 (using star 2 from GCN #204
Not found
 
 
).
These values include the contribution of the proposed underlying host
galaxy.  To have the contribution of the OT alone these value should be
increased by about 0.25 magnitudes.

R = 19.9 +/- 0.2 is compatible with the power-law decay with index
-1.5 found by Bloom et al. (GCN #208
Not found
 
 
) as we would expect to find
about R = 20.1 using the R = 18.2 on Jan 23.565 UT and R = 21.3 for the
underlying galaxy (GCN #201
Not found
 
 
).

This report may be cited.


[GCN OP NOTE:  This circular was actually received at 12:40:01 UT, but was 
delayed in distribution due to the submitter not having prior vetting.]