TITLE:   GCN GRB OBSERVATION REPORT
NUMBER:  3988
SUBJECT: GRB 050915b, SMARTS optical/IR observations
DATE:    05/09/16 01:07:56 GMT
FROM:    Bethany Cobb at Yale U  <cobb@astro.yale.edu>

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

Using the ANDICAM instrument on the 1.3m telescope at CTIO, we
obtained optical/IR imaging of the error region of GRB 050915b
(GCN 3987, Falcone et al.), starting 2.0 hours after the burst at
2005-09-15 23:23 UT.  Our optical images, in V and I, have a field of view 
of 6'x6' and, therefore, cover the entire GRB error circle.
Our IR images, in J and K, have a smaller field of view, covering a region 
totaling ~6 square arcminutes in the middle of the quoted error region.

Visual comparison of the optical images to the SDSS
and the IR images to 2MASS frames does not reveal any new sources.
Preliminary image differencing, using the ISIS image subtraction
program, also does not reveal any significant variable source within the 
GRB error region.

Analysis of this data is ongoing.