GCN Circular 6145
H.-W. Chen (U Chicago), K. Glazebrook (Swinburne University), and J. S. Bloom (UC Berkeley) report on behalf of a larger collaboration: "We obtained 2x900 sec dithered exposures of the field around GRB070224 (Racusin et al., GCN 6137), using GMOS and an i' filter on the Gemini south telescope. The observations started at Feb 25.102 UT, ~ 6 hours after the initial Swift trigger. We continued the observations with 2x900 sec dithered exposures in the z'-band, starting at Feb 25.125 UT. Within the refined XRT position (Racusin et al., GCN 6143), we detect a compact source at RA(J2000)=11:56:06.6 and Dec(J2000)=-13:19:48.9 (+/- 350 mas relative to USNO B1.0) that shows no apparent changes in the brightness between two exposures of 15 min apart. We note the presence of extremely faint (~2 sigma) source at RA(J2000)=11:56:06.5 and Dec(J2000)=-13:19:49.9 in the first i'-band exposure. Further analysis is underway."