GCN Circular 29706
Subject
GRB 210318A: Swift/UVOT Upper Limits
Date
2021-03-24T11:05:42Z (3 years ago)
From
Mike Siegel at PSU/Swift MOC <mhs18@psu.edu>
M. H. Siegel (PSU) and E. Troja (NASA/GSFC/UMCP)
report on behalf of the Swift/UVOT team:
The Swift/UVOT began settled observations of the field of GRB 210318A
127 s after the BAT trigger (Troja et al., GCN Circ. 29662).
No optical afterglow consistent with the XRT position
(Troja et al. GCN Circ. 29662)
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 127 277 147 >20.5
u_FC 285 535 246 >19.9
white 127 1188 353 >21.0
v 614 1064 58 >18.6
b 541 1163 58 >19.3
u 285 535 246 >19.9
The magnitudes in the table are not corrected for the Galactic extinction
due to the reddening of E(B-V) = 0.017 in the direction of the burst
(Schlegel et al. 1998).