GCN Circular 29695
Subject
GRB 210318B: Swift/UVOT Upper Limits
Date
2021-03-23T03:30:27Z (3 years ago)
From
Sam LaPorte at PSU <sjl5346@psu.edu>
GRB 210318B: Swift/UVOT Upper Limits
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 210318B
70 s after the BAT trigger (Troja et al., GCN Circ. 29663).
No optical afterglow consistent with the XRT position
(Troja et al. GCN Circular 29663)
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 70 219 147 >20.0
u_FC 282 532 246 >20.1
white 70 1357 373 >20.9
v 612 1406 97 >18.2
b 538 1500 92 >19.1
u 282 1479 324 >20.1
w1 661 1455 97 >18.8
m2 1066 1430 58 >19.3
w2 588 1382 97 >19.0
The magnitudes in the table are not corrected for the Galactic extinction
due to the reddening of E(B-V) = 1.718 in the direction of the burst
(Schlegel et al. 1998).