GCN Circular 23014
Subject
GRB 180721A: Swift/UVOT Upper Limits
Event
Date
2018-07-22T16:42:55Z (7 years ago)
From
Paul Kuin at MSSL <npkuin@gmail.com>
N. P. M. Kuin (UCL-MSSL) and B. Sbarufatti (PSU)
report on behalf of the Swift/UVOT team:
The Swift/UVOT began settled observations of the field of GRB 180721A
120 s after the BAT trigger (Sbarufatti et al., GCN Circ. 22994).
No optical afterglow consistent with the XRT position (Goad et al, GCN
Circ. 22997) 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
u_FC 120 370 246 >20.1
v 425 1693 156 >19.1
b 375 1642 175 >19.9
u 120 1617 529 >20.1
w1 474 1742 156 >19.6
m2 1697 1717 19 >18.3
w2 401 1668 156 >20.5
The magnitudes in the table are not corrected for the Galactic extinction
due to the reddening of E(B-V) = 0.07 in the direction of the burst
(Schlegel et al. 1998).