GCN Circular 22638
Subject
GRB 180411A: Swift/UVOT Upper Limit
Date
2018-04-12T10:53:05Z (6 years ago)
From
Alice Breeveld at MSSL-UCL <a.breeveld@ucl.ac.uk>
A. A. Breeveld (UCL-MSSL) and Z. Liu (NAOC/U. Leicester)
report on behalf of the Swift/UVOT team:
The Swift/UVOT began observations of the field of GRB 180411A 64 s after
the BAT trigger (Liu et al., GCN Circ. 22630) with a settling exposure
in the V filter. The UVOT safety circuit tripped 3.4s into the following
UV grism exposure, most likely due to the bright star HD223128, 5.08
arcmin from the burst position.
No optical afterglow consistent with the enhanced XRT position (Gibson
et al. GCN Circ. 22632) is seen in the 9.3s V settling exposure to a
preliminary 3-sigma upper limit of 16.8 mag using the UVOT photometric
system (Breeveld et al. 2011, AIP Conf. Proc. 1358, 373).
The magnitude is not corrected for the Galactic extinction
due to the reddening of E(B-V) = 1.104 in the direction of the burst
(Schlegel et al. 1998).