GCN Circular 29259
Subject
GRB 210104B: Swift/UVOT Upper Limits
Event
Date
2021-01-05T14:18:56Z (5 years ago)
From
Alice Breeveld at MSSL-UCL <a.breeveld@ucl.ac.uk>
A. A. Breeveld (UCL-MSSL) and S. L. Laha (GSFC/UMBC/CRESST) report on behalf of the Swift/UVOT team:
The Swift/UVOT began settled observations of the field of GRB 210104B 84 s after the BAT trigger
(Laha et al., GCN Circ. 29243).
No optical afterglow consistent with the XRT position (Evans et al. GCN Circ. 29253) 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 84 234 147 >20.5
u_FC 296 546 246 >19.8
white 84 753 172 >20.7
v 625 645 19 >17.6
b 551 743 39 >19.1
u 296 719 265 >19.9
The magnitudes in the table are not corrected for the Galactic extinction due to the reddening of
E(B-V) = 0.79 in the direction of the burst (Schlegel et al. 1998).