TITLE:   GCN CIRCULAR
NUMBER:  37678
SUBJECT: GRB 241001A: Swift/UVOT Detection
DATE:    24/10/02 12:35:15 GMT
FROM:    Alice Breeveld at MSSL-UCL <a.breeveld@ucl.ac.uk>

A.A. Breeveld (UCL-MSSL) and R. Caputo (GSFC) report on behalf of the Swift/UVOT team:

The Swift/UVOT began settled observations of the field of GRB 241001A 6534 s after the SVOM/ECLAIRS trigger (Dagoneau et al. GCN 37655).
A fading source consistent with the optical afterglow position given by Izzo et al. (GCN 37673), and the XRT candidate (Osborne et al. GCN 37670) is found in the U band images.
Preliminary magnitudes using the UVOT photometric system (Breeveld et al. 2011, AIP Conf. Proc. 1358, 373) for the initial exposures are:

Filter     T_start(s)   T_stop(s)      Exp(s)         Mag

u          6533.5       8438.8         1875           20.20 ± 0.15
u         12310.1      13655.8         2649           20.91 ±0.24

The magnitudes in the table are not corrected for the Galactic extinction due to the reddening of E(B-V) = 0.013 in the direction of the burst (Schlegel et al. 1998).