TITLE: GCN CIRCULAR NUMBER: 40933 SUBJECT: GRB 250702F: Swift/UVOT Detection DATE: 25/07/04 05:01:32 GMT FROM: Mike Siegel at PSU/Swift MOC mhs18@psu.edu
M. H. Siegel (PSU) and N. J. Klingler (GSFC/UMBC/CRESSTII) report on behalf of the Swift/UVOT team:
The Swift/UVOT began settled observations of the field of GRB 250702F 97 s after the BAT trigger (Klingler et al., GCN Circ. 40894). A source consistent with the XRT position (Goad et al., GCN Circ. 40902) is detected in the initial UVOT exposures. The source is detected in all filters except for uvw2 and only marginally in uvm2, which would be consistent with the redshift reported by de Ugarte Postigo et al. (GCN Circ. 40901).
The preliminary UVOT position is: RA (J2000) = 14:11:44.66 = 212.93610 (deg.) Dec (J2000) = +16:44:55.1 = 16.74863 (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
white 97 247 147 15.86 +/- 0.02 v 5904 6104 197 18.39 +/- 0.14 b 3878 4077 197 18.42 +/- 0.09 u 309 515 202 15.04 +/- 0.03 m2 9609 10131 514 19.53 +/- 0.24 w2 5699 5899 197 >19.2
The magnitudes in the table are not corrected for the Galactic extinction due to the reddening of E(B-V) = 0.017 in the direction of the burst (Schlegel et al. 1998).
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