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GCN Circular 37296

Subject
GRB 240825A: Swift/UVOT Detection
Date
2024-08-26T12:54:52Z (a month ago)
Edited On
2024-08-26T13:40:13Z (a month ago)
From
Paul Kuin at MSSL <npkuin@gmail.com>
Edited By
Vidushi Sharma at NASA GSFC/UMBC <vidushi.sharma@nasa.gov> on behalf of Rahul Gupta at NASA GSFC <rahulbhu.c157@gmail.com>
Via
email
N. P. M. Kuin (UCL-MSSL) and R. 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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