GCN Circular 33292
Subject
GRB 230204B: Swift/UVOT Upper Limits
Date
2023-02-06T20:50:39Z (a year ago)
From
Mike Siegel at PSU/Swift MOC <mhs18@psu.edu>
M. H. Siegel (PSU) 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 230204B
80 ks after the MAXI trigger (Serino et al., GCN Circ. 33265).
No optical afterglow consistent with the optical or XRT positions
(Swain et al., GCN Circ. 33269, Smartt et al., GCN Circ. 33278, D���Elia et al.,
GCN Circ. 33285) 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 initial exposures are:
Filter T_start(s) T_stop(s) Exp(s) Mag
v 81062 109630 314 >19.1
b 80652 109220 314 >20.1
u 80567 109136 314 >19.8
w1 80403 109052 629 >20.1
m2 81146 109877 2154 >20.9
w2 80737 109546 1259 >20.7
The magnitudes in the table are not corrected for the Galactic extinction
due to the reddening of E(B-V) = 0.109 in the direction of the burst
(Schlegel et al. 1998).