TITLE: GCN CIRCULAR NUMBER: 6586 SUBJECT: GRB 070628: Watcher Observations DATE: 07/06/28 21:56:11 GMT FROM: Gary Melady at UCD Gary Melady (University College Dublin), John French (UCD), Petr Kubanek (GACE Valencia), Martin Jelinek (IAA CSIC Granada) report on behalf of the Watcher collaboration: The Watcher 40cm robotic telescope, located at Boyden Observatory, South Africa, responded to Swift Trigger 283320 (GRB 070628, Holland et al. GCN 6584). when the dome opened at 15:17:29 UT, 36.43 minutes after the trigger. However the bright evening sky rendered the earliest images unusable. An unfiltered 60s exposure taken under twilight conditions at 16:12:48 UT, 91.76 minutes after the Swift trigger, showed no new source in the UVOT error box (as reported by Gronwall et al., GCN 6585) down to an R-band limiting magnitude of approx 16.2 (in comparison to USNO-B1). We combined 27 subsequent 60s exposures to create a 1620s unfiltered image with an exposure mid-time of 16:28:05 (108.05 minutes after the trigger). The later images were taken at high air mass as the target was setting. This shows no new source in the error box down to an R-band limiting magnitude of approx 17.2. The target set at our location at 18:20 UT so no further observations will be made. This message may be cited.