TITLE: GCN CIRCULAR NUMBER: 6814 SUBJECT: GRB 070920b, SMARTS optical observation DATE: 07/09/21 18:11:29 GMT FROM: Bethany Cobb at Yale U B. E. Cobb, part of the larger SMARTS consortium, reports: Using the ANDICAM instrument on the 1.3m telescope at CTIO, we obtained optical imaging of the error region of GRB 070920b (Racusin et al. GCN 6808) with a mid-exposure time of ~4.4 hours post-burst (2007-09-21 01:29 UT). The total summed exposure time amounted to 36 minutes in I, but images were taken under poor weather conditions. Comparison to the DSS reveals no new sources in the refined GRB error region (Barthelmy et al. GCN 6811). Our I-band limiting magnitude is I~20.8 (calibrated using several USNO-B1.0 stars).