[vsnet-grb-info 2155] GRB 050915b, SMARTS optical/IR observations of the XRT position

[GCN Circulars]

TITLE:   GCN GRB OBSERVATION REPORT
NUMBER:  3994
SUBJECT: GRB 050915b, SMARTS optical/IR observations of the XRT position
DATE:    05/09/16 23:09:33 GMT
FROM:    Bethany Cobb at Yale U  <cobb at astro.yale.edu>

B. E. Cobb and C. D. Bailyn (Yale), part of the larger SMARTS
consortium, report:

Our ANDICAM observations reported in GCN 3988 were re-examined
following the detection of the X-ray afterglow of GRB 050915b (GCN 3989, 
Falcone et al.). The position of the X-ray afterglow was captured in both 
our optical and IR images.

Three sources are detected within the X-ray afterglow error region:

        RA           DEC
A) 14:36:26.04  -67:24:41.4
B) 14:36:26.35  -67:24:32.2
C) 14:36:27.30  -67:24:39.3


The first source (A) has a stellar profile and has previously been clearly
detected in both the SDSS and 2MASS surveys.  The other two sources (B and C)
appear only slightly above the detection limits of our ANDICAM images.  
Sources B and C are also weakly detected in the SDSS (and possibly in 2MASS).  
These two sources, particularly source B, might be extended, though this is 
uncertain due to the low significance of their detection.

The brightness of these sources does not vary significantly over our 
period of observation.

Total summed exposure times amounted to 30 minutes in I and V and
24 minutes in J and K, with a mid-exposure time of 2005-09-15 00:01 UT
(~2.6 hours post-burst). The preliminary limiting magnitudes of our 
images are as follows:
V < 21.4 +/- 0.1
I < 21.3 +/- 0.1
J < 18.3 +/- 0.2
K < 17.8 +/- 0.2