TITLE: GCN CIRCULAR NUMBER: 6754 SUBJECT: GRB 070810B: XRT refined analysis DATE: 07/08/11 01:59:15 GMT FROM: Rhaana Starling at U of Leicester R. Starling (U. Leicester), C. Markwardt (CRESST/GSFC/UMD) and F.E. Marshall (NASA/GSFC) report, on behalf of the Swift XRT team: We have analysed 7.2 ks of Swift XRT photon counting mode data, beginning 70 s and ending 13.8 ks after the BAT trigger, for the short GRB 070810B (trigger=287409; Marshall et al., GCN Circ. 6743). We do not detect any X-ray sources at 3-sigma significance or greater within the refined BAT error circle (Sakamoto et al., GCN Circ. 6753). Two low significance (2-sigma) possible sources are found within the BAT refined error circle at the following positions: Source 1 RA (J2000) = 00h 35m 51.2s Dec (J2000) = +08d 51' 21.3'' Source 2 RA (J2000) = 00h 35m 50.0s Dec (J2000) = +08d 48' 45.0'' Using the Bayesian method we find that both sources have between 4 and 26 counts at the 99% confidence level. It is not possible to determine at this stage whether or not either of these sources are fading. We note that Source 2 lies 1.1 arcmin from the galaxy 2MASX J00355339+0849273 (= LEDA 1354367; RA, Dec (J2000) = 00h 35m 53.39s, +08d 49' 27.3''), which has angular diameter approximately 0.7 x 0.3 arcmin. This is an official product of the Swift XRT team.