GCN Circular 36214
Subject
GRB 240421B: Swift/UVOT Upper Limits
Date
2024-04-21T19:04:49Z (8 months ago)
From
Paul Kuin at MSSL <npkuin@gmail.com>
Via
email
N. P. M. Kuin (UCL-MSSL) and M. Williams (PSU)
report on behalf of the Swift/UVOT team:
The Swift/UVOT began settled observations of the field of GRB 240421B
130s after the BAT trigger (Williams et al., GCN Circ. 36208). No
optical afterglow consistent with the XRT position Beardmore et al.
(GCN Circ. 36213) 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 130 279 148 >20.6
u_FC 343 592 246 >20.2
white 130 1708 218 >20.9
v 672 1764 78 >18.4
b 598 1854 84 >19.8
u 343 1827 339 >20.2
w1 721 1813 78 >19.4
w2 648 1568 78 >18.8
The magnitudes in the table are not corrected for the Galactic extinction
due to the reddening of E(B-V) = 0.182 in the direction of the burst
(Schlegel et al. 1998).