GCN Circular 33683
Subject
GRB 230423A: Swift/UVOT Upper Limits
Date
2023-04-25T20:34:48Z (a year ago)
From
Paul Kuin at MSSL <npkuin@gmail.com>
N. Paul Kuin (UCL-MSSL) and Riccardo Brivio (INAF-OAB)
report on behalf of the Swift/UVOT team:
The Swift/UVOT began settled observations of the field of GRB 230423A
731 s after the BAT trigger (Brivio et al., GCN Circ. 33677). No optical
afterglow consistent with the XRT position Salvaggio et al., GCN
Circulars 33679, 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 731 881 147 >20.9
white 731 5415 491 >21.4
b 5010 5210 197 >20.0
u 4805 5004 197 >19.2
w2 5420 5544 122 >19.5
The magnitudes in the table are not corrected for the Galactic extinction
due to the reddening of E(B-V) = 0.137 in the direction of the burst
(Schlegel et al. 1998).