GCN Circular 22674
Subject
GRB 180425A: Swift/UVOT Upper Limits
Date
2018-04-25T14:10:33Z (7 years ago)
From
Sam Emery at MSSL-UCL <samuel.emery.15@ucl.ac.uk>
S.W.K. Emery (UCL-MSSL) and F. E. Marshall (NASA/GSFC)
report on behalf of the Swift/UVOT team:
The Swift/UVOT began settled observations of the field of GRB 180425A
88 s after the BAT trigger (Marshall et al., GCN Circ. 22672).
No optical afterglow consistent with the XRT position
(Osborne et al., GCN Circ. 22673)
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 early exposures are:
Filter T_start(s) T_stop(s) Exp(s) Mag
white 88 1201 353 >21.0
u 302 1152 285 >20.5
v 631 1250 78 >18.5
b 557 1176 58 >19.4
uvw1 680 1299 78 >19.0
uvm2 827 1275 58 >18.5
uvw2 606 1226 58 >19.0
The magnitudes in the table are not corrected for the Galactic extinction
due to the reddening of E(B-V) = 0.03 in the direction of the burst
(Schlegel et al. 1998).