TITLE: GCN CIRCULAR NUMBER: 11514 SUBJECT: GRB110102A: Swift/UVOT observations DATE: 11/01/03 12:41:16 GMT FROM: Samantha Oates at MSSL S. R. Oates (MSSL-UCL) and M. De Pasquale (MSSL-UCL) report on behalf of the Swift-UVOT team The Swift/UVOT began settled observations of the field of GRB 110102A 156 s after the BAT trigger (Oates et al., GCN Circ. 11509). The optical afterglow is detected in the white, v, b and u filters at a refined UVO position RA(J2000)= 245.88087 deg, DEC(J2000) = 7.61383, which is: RA (J2000) = 16:23:31.41 Dec (J2000) = +07:36:49.8 with an estimated uncertainty of 0.5 arcsec (radius, 90% confidence). This position is consistent with the enhanced XRT position (Goad et al., GCN Circ. 11510). The detection in u suggests a redshift of <2.5. Preliminary magnitudes using the UVOT photometric system (Poole et al. 2008, MNRAS, 383, 627) for single and summed exposures are: Filter T_start(s) T_stop(s) Exp(s) Mag/3sigUL ##################################################### wh (FC) 156 306 147 17.97 +/- 0.06 wh 868 1018 147 18.39 +/- 0.08 u (FC) 314 564 246 17.98 +/- 0.09 u 1122 1315 39 18.89 +/- 0.62 v 816 835 19 17.86 +/- 0.53 b 597 589 19 17.60 +/- 0.20 uvw1 693 6331 452 > 20.09 uvm2 668 6126 292 > 19.87 uvw2 619 7152 471 > 20.35 ##################################################### The values quoted above are not corrected for the Galactic extinction due to the reddening of E(B-V) = 0.08 in the direction of the burst (Schlegel et al. 1998).