TITLE:   GCN CIRCULAR
NUMBER:  41766
SUBJECT: EP250908b/EP#01709240653: Swift/UVOT Detection
DATE:    25/09/09 20:26:09 GMT
FROM:    Alice Breeveld at MSSL-UCL <a.breeveld@ucl.ac.uk>

A.A. Breeveld (UCL-MSSL) and M. Ferro (INAF-OAB) report on behalf of the Swift/UVOT team:

The Swift/UVOT began settled observations of the field of the EP/WXT detected burst EP250908b (Yin et al., GCN Circ. 41752) 1103 s after the trigger. The afterglow reported by Ma et al. (GCN Circ. 41758) and also detected as source 1 in the Swift/XRT (Evans et al., GCN Circ. 41765), is detected in the initial U-band exposure.

The preliminary magnitude using the UVOT photometric system (Breeveld et al. 2011, AIP Conf. Proc. 1358, 373) for the initial exposure is:

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

u              1103         2836           1706           20.0 +/- 0.14

The magnitudes in the table are not corrected for the Galactic extinction due to the reddening of E(B-V) = 0.048 in the direction of the burst (Schlegel et al. 1998).