TITLE: GCN CIRCULAR NUMBER: 6445 SUBJECT: GRB 070521: SARA upper limit DATE: 07/05/22 00:21:31 GMT FROM: Adria C. Updike at Clemson U A. C. Updike, J. R. Puls, and D. H. Hartmann (Clemson University) report on behalf of the Clemson GRB Follow-Up Team: We imaged the field of GRB 070521 (GCN 6431, Guidorzi et al.) beginning 14 minutes after the trigger (279935) with the SARA 0.9m at Kitt Peak under decent weather conditions. In 50 minutes of stacked exposures in the R band, we detect no new sources in the XRT error circle down to a limiting magnitude of 20 +/- 0.4. We do not detect the source noted by Hattori et al. (GCN 6444). This magnitude is based on calibration to 5 USNO B1.0 stars. The SARA Homepage can be found at: http://saraobservatory.org This message may be cited.