TITLE: GCN CIRCULAR NUMBER: 17472 SUBJECT: GRB 150213B: Swift/UVOT Detection DATE: 15/02/14 18:21:33 GMT FROM: Frank Marshall at GSFC F. E. Marshall (NASA/GSFC) and C. Pagani (U. Leicester) report on behalf of the Swift/UVOT team: The Swift/UVOT began settled observations of the field of GRB 150213B 153 s after the BAT trigger (Pagani et al., GCN Circ. 17464). A source consistent with the XRT position (Osborne et al. GCN Circ. 17469) is detected in the initial UVOT exposures. The preliminary UVOT position is: RA (J2000) = 16:53:48.67 = 253.45278 (deg.) Dec (J2000) = +34:11:19.3 = 34.18869 (deg.) with an estimated uncertainty of 0.46 arc sec. (radius, 90% confidence). Preliminary detections and 3-sigma upper limits using the UVOT photometric system (Breeveld et al. 2011, AIP Conf. Proc. 1358, 373) for the early exposures are: Filter T_start(s) T_stop(s) Exp(s) Mag white 153 302 147 18.61 +/- 0.07 v 4498 23548 966 >20.3 b 3883 12039 961 >20.7 u 310 532 218 18.76 +/- 0.15 w1 4910 10539 1082 20.76 +/- 0.21 m2 4703 16622 1224 21.25 +/- 0.32 w2 4293 22956 1279 21.48 +/- 0.31 The magnitudes in the table are not corrected for the Galactic extinction due to the reddening of E(B-V) = 0.02 in the direction of the burst (Schlegel et al. 1998).