GCN Circular 9481
B. E. Cobb (UC Berkeley) reports: Using the ANDICAM instrument on the 1.3m telescope at CTIO, we obtained optical/IR imaging of the error region of GRB 090531b (GCN 9461, Cummings et al.) over two epochs with mid-exposure times of 2009-06-01 02:56 UT and 2009-06-02 05:26 UT (8.3 and 34.8 hours post-burst). Total summed exposure times for each observation amounted to 36 minutes in R and 30 minutes in J. While there are a number of sources in and around the position of the GRB X-ray afterglow (GCN 9463, Sbarufatti et al.; GCN 9480, Rossi et al.), image differencing of the two epochs using the ISIS image subtraction program does not reveal any significant variable source. The sky limiting magnitude of the images is I>21.1 and J>18.5 (where optical photometry is calibrated using USNO-B1 stars and IR photometry with 2MASS; these limits have not been corrected for Galactic reddening).