GCN Circular 23064
Subject
GRB 180728A: Swift/UVOT Detection
Event
Date
2018-07-31T03:04:49Z (7 years ago)
From
Sam LaPorte at PSU <sjl5346@psu.edu>
GRB 180728A: Swift/UVOT Detection
S. J. LaPorte (PSU) and R. L. C. Starling (U. Leicester)
report on behalf of the Swift/UVOT team:
The Swift/UVOT began settled observations of the field of GRB 180728A
1740 s after the BAT trigger (Starling et al., GCN Circ. 23046).
A source consistent with the enhanced XRT position
(Osborne et al. GCN Circ. 23051)
is detected in the initial UVOT exposures.
The preliminary UVOT position is:
RA (J2000) = 16:54:15.53 = 253.56472 (deg.)
Dec (J2000) = -54:02:40.2 = -54.04451 (deg.)
with an estimated uncertainty of 0.43 arc sec. (radius, 90% confidence),
consistent with MASTER OT J165415.75-540239.27 (Lipunov et al., GCN #23050).
Preliminary detections 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 1740 1890 147 16.25 +/- 0.03
white 7713 15148 465 17.28 +/- 0.03
v 1897 1917 20 16.07 +/- 0.14
b 1995 2013 18 16.58 +/- 0.10
u 1970 1990 20 15.93 +/- 0.10
w1 1946 1966 20 16.20 +/- 0.17
m2 1921 2114 39 16.60 +/- 0.18
w2 2045 2065 19 16.37 +/- 0.19
The magnitudes in the table are not corrected for the Galactic extinction
due to the reddening of E(B-V) = 0.29 in the direction of the burst
(Schlegel et al. 1998).