GCN Circular 4877
P. Schady (PSU/MSSL-UCL) C. Pagani (PSU) on behalf of the Swift/UVOT team The Swift/UVOT began taking data on the field of GRB 060313 at 00:13:23 UT on 2006-03-13, approximately 79s after the BAT trigger (Pagani et al., GCN 4867). The afterglow is detected above the 2-sigma level in the V, B and UVW2 filter at a position consistent with that reported by Cobb et al. (GCN 4872), and there is a tenuous detection in the U and UVW1 band coadded exposures at the 1.4 and 1.2 sigma level, respectively. The detection in UVW2 implies that the Lyman limit must be blueward of ~2500 A, providing a redshift upper limit of z <~1.7. All detections above 2-sigma and the 2-sigma upper limits from the coadded image of a set of exposure for each filter are as follows: Filter T_range(s) Exp(s) Average mag/UL sigma V 177-6963 933 20.03+/-0.39 2.9 B 469-5453 953 20.69+/-0.48 2.7 U 415-844 100 > 19.95 UVW1 361-790 100 > 18.91 UVM2 307-736 100 > 18.89 UVW2 578-900 950 20.98+/-0.5 2.2 These magnitudes are uncorrected for Galactic extinction; E(B-V) = 0.067.