GCN Circular 37123
Subject
GRB 240809A: Swift/UVOT Detection
Date
2024-08-10T01:58:51Z (4 months ago)
From
Sam Shilling at Lancaster University <shilling.sam@gmail.com>
Via
Web form
S.P.R. Shilling (Lancaster U.) and P. A. Evans (U. Leicester)
report on behalf of the Swift/UVOT team:
The Swift/UVOT began settled observations of the field of GRB 240809A
98 s after the BAT trigger (Evans et al., GCN Circ. 37110).
A source consistent with the enhanced XRT position
(Osborne et al., GCN Circ. 37115) is detected in the initial UVOT exposures.
The preliminary UVOT position is:
RA (J2000) = 15:50:10.52 = 237.54385 (deg.)
Dec (J2000) = -02:19:03.0 = -2.31751 (deg.)
with an estimated uncertainty of 0.42 arc sec. (radius, 90% confidence).
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 98 248 147 14.42 +/- 0.02
v 640 660 19 16.11 +/- 0.14
b 565 585 19 16.28 +/- 0.09
u 310 560 246 15.13 +/- 0.03
w1 689 709 19 16.19 +/- 0.17
m2 665 1263 78 17.31 +/- 0.18
w2 616 1387 97 18.33 +/- 0.24
The magnitudes in the table are not corrected for the Galactic extinction
due to the reddening of E(B-V) = 0.249 in the direction of the burst
(Schlegel et al. 1998).