GCN Circular 29109
Subject
GRB 201221A: Swift/UVOT Upper Limits
Event
Date
2020-12-21T22:06:23Z (6 years ago)
From
Alice Breeveld at MSSL-UCL <a.breeveld@ucl.ac.uk>
A. A. Breeveld (UCL-MSSL) and K. L. Page (U. Leicester) report on behalf of the Swift/UVOT team:
The Swift/UVOT began settled observations of the field of GRB 201221A 141 s after the BAT trigger
(Page et al., GCN Circ. 29096). No optical afterglow consistent with the optical position (Malesani
et al. GCN Circ. 29100) 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 141 291 147 >20.0
u_FC 300 549 246 >19.1
white 141 951 257 >20.2
v 629 4762 236 >18.8
b 555 748 39 >18.3
u 300 5271 357 >19.5
w1 679 5172 236 >19.4
m2 654 4967 236 >19.2
w2 605 4557 235 >19.4
The magnitudes in the table are not corrected for the Galactic extinction due to the reddening of
E(B-V) = 0.11 in the direction of the burst (Schlegel et al. 1998).