GCN Circular 39968
Subject
GRB 250328A: Swift/UVOT Detection
Date
2025-03-31T10:23:48Z (4 days ago)
From
noelklin@umbc.edu
Via
Web form
N. Klingler (NASA-GSFC / UMBC / CRESST II), 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 250328A 3254 s after the SVOM trigger sb25032803 (GCN Circ. 39910). A source consistent with the XRT position (Evans et al., GCN Circ. 39967) is detected in the initial UVOT exposures and appears to be fading.
Preliminary detections and 3-sigma upper limits for the early exposures are:
Filter T_start(s) T_stop(s) Exp(s) Mag(AB)
u 3254 4993 1711 21.93 +/- 0.30
u 8758 8994 232 >21.01
u 177580 190264 970 >21.88
The magnitudes in the table are not corrected for the Galactic extinction due to the reddening of E(B-V) = 0.018 in the direction of the burst (Schlegel et al. 1998).
This is an official data product of the Swift/UVOT team.