GCN Circular 6120
Subject
Swift/UVOT refined analysis of GRB070220
Event
Date
2007-02-20T20:00:11Z (19 years ago)
From
Massimiliano de Pasquale at MSSL-UCL <mdp@mssl.ucl.ac.uk>
M. De Pasquale (MSSL/UCL) and M. Stamatikos (NASA/ORAU) report on
behalf of the Swift UVOT team:
The Swift/UVOT observed the field of GRB 070220 starting 70 s
after the BAT trigger (Stamatikos et al. 2007, GCN Circ. 6114) with
the settling exposure.
We do not find any source, in any of the UVOT observations, inside
the refined XRT error circle (Beardmore et al., 2007 GCN Circ. 6118).
We have the following 3-sigma upper limits for a source inside the
XRT error circle in the first exposure with White filter and in the
co-added frames with all filters:
Filter T_start T_stop Exp(s) Mag (3-sigma UL)
-----------------------------------------------------------------
White 90 190 98 19.6
V 195 7101 1278 20.0
B 673 6487 276 20.2
U 649 7627 410 20.0
UVW1 625 7510 498 19.7
UVM2 601 7306 498 20.1
UVW2 701 6897 498 20.1
White 90 6691 638 20.6
-----------------------------------------------------------------
The values quoted above are not corrected for the expected Galactic
extinction corresponding to a reddening of E_{B-V} = 0.9 mag towards
the direction of the burst (Schlegel et al. 1998).