GCN Circular 29885
Subject
GRB 210421A: Swift/UVOT Upper Limits
Date
2021-04-22T18:53:07Z (3 years ago)
From
Samantha Oates at MSSL <samantha.oates@alumni.ucl.ac.uk>
S. R. Oates (U.Birmingham) and M. J. Moss (GWU)
report on behalf of the Swift/UVOT team:
The Swift/UVOT began settled observations of the field of GRB 210421A
96 s after the BAT trigger (Moss et al., GCN Circ. 29849).
No optical afterglow consistent with the XRT position
(Evans et al., GCN Circ. 29865).
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 96 246 147 >20.4
white 96 1912 191 >20.6
v 1608 1800 39 >17.9
b 1534 1899 58 >19.2
u_FC 308 484 173 >19.5
u 308 1874 211 >19.6
uvw1 1658 1850 39 >18.1
uvm2 1633 1825 39 >17.9
uvw2 1584 1776 39 >18.3
The magnitudes in the table are not corrected for the Galactic extinction
due to the reddening of E(B-V) = 0.318 in the direction of the burst
(Schlegel et al. 1998).