GCN Circular 6454
Subject
GRB 070521: Swift/UVOT Upper Limits
Date
2007-05-22T16:16:15Z (17 years ago)
From
Frank Marshall at GSFC <marshall@milkyway.gsfc.nasa.gov>
F.E. Marshall (NASA/GSFC) and C. Guidorzi (U. Bicocca & INAF-OAB)
report on behalf of the Swift/UVOT team:
The Swift/UVOT observed the field of GRB 070521 starting 82 s after
the BAT trigger (Guidorzi et al., GCN Circ. 6431). We do not find any source
in any of the UVOT observations inside the refined XRT error circle
(Guidorzi et al., GCN Circ. 6452). The 3-sigma upper limits for detecting
a source in the first finding chart (FC) exposure and co-added frames are:
Filter T_start(s) T_stop(s) Exp(s) Mag (3-sigma UL)
White (FC) 82 182 98 >20.6
White 82 24605 1884 >22.3
V 187 17181 1451 >20.4
B 5304 23879 1967 >22.0
U 5099 22968 1278 >21.7
UVW1 4894 18810 1111 >21.1
UWM2 4869 18085 1279 >20.8
UVW2 5713 12897 792 >21.1
The values quoted above are not corrected for the expected Galactic
extinction corresponding to a reddening of E(B-V) = 0.03 mag towards
the direction of the burst (Schlegel et al. 1998).