TITLE: GCN CIRCULAR NUMBER: 37296 SUBJECT: GRB 240825A: Swift/UVOT Detection DATE: 24/08/26 12:54:52 GMT FROM: Paul Kuin at MSSL npkuin@gmail.com
N. P. M. Kuin (UCL-MSSL) and Gupta (NASA GSFC) report on behalf of the Swift/UVOT team:The Swift/UVOT began settled observations of the field of
GRB 240825A 93 s after the BAT trigger (Gupta et al., GCN Circ. 37274). A source consistent with the XRT position (Evans et al. GCN Circ. 37290 is detected in the initial UVOT exposures.
The preliminary UVOT position is: RA (J2000) = 22:58:17.26 = 344.57192 (deg.) Dec (J2000) = +01:01:36.9 = 1.02691 (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 93 243 147 15.58 +/- 0.02 v 807 827 20 17.02 +/- 0.20 b 561 580 20 17.54 +/- 0.15 u 305 555 246 16.93 +/- 0.05 w1 684 1281 58 18.55 +/- 0.30
The magnitudes in the table are not corrected for the Galactic extinction due to the reddening of E(B-V) = 0.063 in the direction of the burst (Schlegel et al. 1998).
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