TITLE: GCN CIRCULAR NUMBER: 17219 SUBJECT: GRB 141221A: Swift/UVOT Detection DATE: 14/12/22 17:26:04 GMT FROM: Frank Marshall at GSFC F. E. Marshall (NASA/GSFC) and E. Sonbas (NASA/GSFC/Adiyaman Univ.) report on behalf of the Swift/UVOT team: The Swift/UVOT began settled observations of the field of GRB 141221A 84 s after the BAT trigger (Sonbas et al., GCN Circ. 17206). A source consistent with the enhanced XRT position (Beardmore et al. GCN Circ. 17211) is detected in the initial UVOT exposures. The preliminary UVOT position is: RA (J2000) = 13:13:08.81 = 198.28672 (deg.) Dec (J2000) = +08:12:18.8 = 8.20522 (deg.) with an estimated uncertainty of 0.43 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 84 234 147 17.33 ± 0.04 v 626 646 19 17.43 ± 0.26 b 552 571 20 17.92 ± 0.21 u 296 546 246 17.62 ± 0.07 w1 4061 4261 197 >20.0 m2 3856 10742 414 >20.9 w2 6231 6399 165 >20.5 The magnitudes in the table are not corrected for the Galactic extinction due to the reddening of E(B-V) = 0.03 in the direction of the burst (Schlegel et al. 1998).