TITLE: GCN CIRCULAR NUMBER: 33392 SUBJECT: GRB 230228A: Swift/UVOT Upper Limits DATE: 23/03/02 10:15:52 GMT FROM: Alice Breeveld at MSSL-UCL a.breeveld@ucl.ac.uk
A. A. Breeveld (UCL-MSSL) and S. Dichiara (PSU) report on behalf of the Swift/UVOT team:
The Swift/UVOT began settled observations of the field of GRB 230228A 122 s after the BAT trigger (Dichiara et al., GCN Circ. 33378). No optical afterglow consistent with the enhanced XRT position (Beardmore et al., GCN Circ. 33382) is detected in the initial UVOT exposures. Preliminary 3-sigma upper limits using the UVOT photometric system (Breeveld et al. 2011, AIP Conf. Proc. 1358, 373) for the first finding chart (FC) exposure and subsequent exposures are:
Filter T_start(s) T_stop(s) Exp(s) Mag
white_FC 122 272 147 >20.2 u_FC 335 585 246 >19.5 white 122 1706 240 >20.6 v 665 1752 97 >18.8 b 591 1851 88 >19.8 u 335 1830 341 >19.7 w1 714 1806 117 >20.0 m2 689 1780 97 >19.7 w2 640 1731 78 >20.1
The magnitudes in the table are not corrected for the Galactic extinction due to the reddening of E(B-V) = 0.085 in the direction of the burst (Schlegel et al. 1998).