TITLE: GCN CIRCULAR NUMBER: 6884 SUBJECT: GRB 071010B: Bright OT confirmed with TLS DATE: 07/10/11 14:56:36 GMT FROM: Alexander Kann at TLS Tautenburg D. A. Kann, C. Hoegner & R. Filgas (TLS Tautenburg) report: We observed the field of GRB 071010B (Markwardt et al., GCN 6871) with the TLS 1.34m Schmidt telescope under bad weather conditions (low transparency, passing clouds). We obtained 9 600 second integrations in the Rc Filter starting at UT 1:26:44 (0.2 days after the GRB). The afterglow (Oksanen, GCN 6873) is clearly detected on several frames, the others were lost to passing clouds. We measure a refined OT position (J2000) in comparison to the USNO-B1.0 catalog: RA = 10:02:09.24 Dec. = +45:43:49.7 with errors of 0".7. This is in accordance with the position of Oksanen (GCN 6873) and the Swift XRT detection (Kennea et al., GCN 6878). Preliminary photometry on raw images yields a decaying afterglow. Assuming the USNO-B1.0 star at RA = 10:02:06.71, Dec. = +45:42:34.2 (J2000) to have R2 = 17.26, we find the following magnitudes: Date Mid-Time Rc Rc error 11.06361 0.19848 18.61 0.07 11.07113 0.20600 18.73 0.05 11.07865 0.21352 18.87 0.06 11.13149 0.26637 19.21 0.05 Oksanen (GCN 6873) reported the OT to have R > 18 mag already in the first hour, therefore our bright detections may indicate a slow decay or a rebrightening. This GRB was a bright, soft FRED (Markwardt et al., GCN 6877; Golenetskii et al., GCN 6879) with a well determined peak energy. This may indicate an event at relatively low redshift. Further photometric and especially spectroscopic follow-up is encouraged. This message may be cited.