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GCN Circular 6120

Swift/UVOT refined analysis of GRB070220
2007-02-20T20:00:11Z (17 years ago)
Massimiliano de Pasquale at MSSL-UCL <>
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).
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