GCN Circular 37487
Subject
GRB 240912A: Swift/UVOT Detection
Date
2024-09-13T13:30:34Z (2 months ago)
From
Mike Siegel at PSU/Swift MOC <mhs18@psu.edu>
Via
Web form
M. H. Siegel (PSU) 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 240912A
115 s after the BAT trigger (Evans et al., GCN Circ. 37466).
A fading source consistent with the XRT position (Goad et al.,
GCN Circ. 37470) is detected in the initial UVOT exposures.
The preliminary UVOT position is:
RA (J2000) = 08:18:32.40 = 124.63499 (deg.)
Dec (J2000) = +33:59:56.3 = 33.99897 (deg.)
with an estimated uncertainty of 0.43 arc sec. (radius, 90% confidence).
Preliminary detections and 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 (fc) 117 265 144 17.44+/-0.05
white 608 1031 186 17.87+/-0.06
white 1185 1379 38 18.06+/-0.16
v 657 1430 97 17.78+/-0.28
b 583 5154 205 19.08+/-0.25
u (fc) 328 577 245 16.68+/-0.05
u 731 5018 274 18.14+/-0.13
uvw1 707 1479 77 17.76+/-0.25
uvm2 1086 1106 19 >17.18
uvw2 633 1406 97 18.47+/-0.30
The magnitudes in the table are not corrected for the Galactic extinction
due to the reddening of E(B-V) = 0.054 in the direction of the burst
(Schlegel et al. 1998).