GCN Circular 22475
Subject
GRB 180311A: Swift/UVOT Upper Limits
Date
2018-03-12T16:42:41Z (6 years ago)
From
Frank Marshall at Swift/UVOT <marshall@milkyway.gsfc.nasa.gov>
F. E. Marshall (NASA/GSFC) and K. L. Page (U. Leicester)
report on behalf of the Swift/UVOT team:
The Swift/UVOT began settled observations of the field of GRB 180311A
280 s after the BAT trigger (Page et al., GCN Circ. 22468).
No optical afterglow consistent with the enhanced XRT position
(Goad et al. GCN Circ. 22470)
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 280 430 147 >20.3
white 280 6742 589 >21.2
v 437 7155 333 >19.4
b 536 8600 488 >20.9
u 511 7770 561 >20.5
w1 486 7565 330 >20.2
m2 7160 7360 197 >20.3
w2 1187 6950 255 >20.5
The magnitudes in the table are not corrected for the Galactic extinction
due to the reddening of E(B-V) = 0.01 in the direction of the burst
(Schlegel et al. 1998).