TITLE: GCN CIRCULAR NUMBER: 40008 SUBJECT: GRB 250327A: Swift/UVOT Upper Limits DATE: 25/04/02 13:08:08 GMT FROM: Mike Siegel at PSU/Swift MOC mhs18@psu.edu
M. H. Siegel (PSU) and T. M. Parsotan (GSFC) report on behalf of the Swift/UVOT team:
The Swift/UVOT began settled observations of the field of GRB 250327A 13.8 ks after the BAT trigger (Parsotan et al., GCN Circ. 39877). No optical afterglow consistent with the XRT position (Burrows et al., GCN Circ. 39892) GCN Circ. 39977) is detected in the initial UVOT exposures. Preliminary 3-sigma upper limits using the UVOT photometric system (Breeveld et al. 2011, AIP Conf. Proc. 1358, 373) for the first finding chart (FC) exposure and subsequent exposures are:
Filter T_start(s) T_stop(s) Exp(s) Mag
B 25500 43748 1714 >20.88 UVM2 47869 48769 885 >20.28 U 14704 42891 1711 >20.58 V 21282 21402 117 >18.30 UVW1 13797 49176 1885 >20.62 UVW2 20376 21275 885 >20.31 WHITE 26413 27065 633 >20.81
The magnitudes in the table are not corrected for the Galactic extinction due to the reddening of E(B-V) = 0.053 in the direction of the burst (Schlegel et al. 1998).
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