GCN Circular 42298
Subject
GRB 251013C: Swift/UVOT Detection
Event
Date
2025-10-15T19:54:12Z (16 days ago)
From
Mike Siegel at PSU/Swift MOC <mhs18@psu.edu>
Via
Web form
M. H. Siegel (PSU) reports on behalf of the Swift/UVOT team:
The Swift/UVOT began settled observations of the field of GRB 251013C 0.4 ks after the Fermi/SVOM trigger (GCN Circ. 42221, Rakotondrainibe et al., GCN Circ. 42222). A bright source consistent with the XRT position (Evans et al., GCN Circ. 42232) and optical counterpart (Palmerio et al., GCN Circ. 42223, Perez-Garcia et al., GCN Circ. 42225; Konno et al., GCN Circ. 42226; Masi et al., GCN Circ. 42228; Moskvitin, GCN Circ. 42230; Gompertz et al., GCN Circ. 42231; Garnavich, GCN Circ. 42240; Watson et al., GCN Circ. 42241) is detected in the UVOT exposures.
The preliminary UVOT position is:
RA (J2000) = 23:03:20.55 = 345.83562 (deg.)
Dec (J2000) = -00:12:36.9 = -0.21024 (deg.)
with an estimated uncertainty of 0.42 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
u 480 5581 1785 15.22+/-0.03
white 129831 141519 2753 21.66+/-0.20
The magnitudes in the table are not corrected for the Galactic extinction
due to the reddening of E(B-V) = 0.045 in the direction of the burst
(Schlegel et al. 1998).