GCN Circular 27643
Subject
GRB 200425A: Swift/UVOT Upper Limits
Date
2020-04-25T13:23:07Z (4 years ago)
From
Paul Kuin at MSSL <npkuin@gmail.com>
N. P. M. Kuin (UCL-MSSL) and M. G. Bernardini (INAF-OAB)
report on behalf of the Swift/UVOT team:
The Swift/UVOT began settled observations of the field of
GRB 200425A 94 s after the BAT trigger (Bernardini et al.,
GCN Circ. 27638). No optical afterglow consistent with the
XRT position (Bernardini et al. GCN Circ. 27638)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 94 244 147 >20.7
u_FC 253 503 246 >19.9
white 94 728 186 >20.5
v 585 778 39 >18.6
b 510 704 39 >19.1
u 253 679 265 >19.9
w1 635 827 39 >18.4
m2 610 802 39 >18.9
w2 560 753 39 >18.7
The magnitudes in the table are not corrected for the Galactic extinction
due to the reddening of E(B-V) = 0.16 in the direction of the burst
(Schlegel et al. 1998).