TITLE: GCN CIRCULAR NUMBER: 38685 SUBJECT: GRB 241228A: Swift/UVOT Upper Limits DATE: 24/12/28 10:20:23 GMT FROM: Paul Kuin at MSSL npkuin@gmail.com
N. P. M. Kuin (UCL-MSSL) and V. D'Elia (SSDC & INAF-OAR)
report on behalf of the Swift/UVOT team:
The Swift/UVOT began settled observations of the field of GRB 241228A 101 s after the BAT trigger (D'Elia et al., GCN Circ. 38681). No optical afterglow consistent with the XRT position in that circular was 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 101 251 147 >21.0 u_FC 314 564 246 >19.8 white 101 1538 392 >21.3 v 644 1416 97 >19.1 b 570 1514 97 >19.8 u 314 1489 324 >20.0 w1 694 1465 78 >19.2
The magnitudes in the table are not corrected for the Galactic extinction due to the reddening of E(B-V) = 0.091 in the direction of the burst (Schlegel et al. 1998).
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