[vsnet-grb-info 4200] GRB 070107: Possible UVOT Afterglow
GCN Circulars
gcncirc at capella.gsfc.nasa.gov
Tue Jan 9 05:05:31 JST 2007
TITLE: GCN CIRCULAR
NUMBER: 6002
SUBJECT: GRB 070107: Possible UVOT Afterglow
DATE: 07/01/08 20:05:22 GMT
FROM: Padi Boyd at GSFC <padi at milkyway.gsfc.nasa.gov>
GRB 070107: Possible UVOT Afterglow
P. T. Boyd (GSFC), M. Chester (PSU), C. B. Markwardt (CRESST/GSFC/USRA)
and F. E. Marshall (GSFC) report on behalf of the Swift team:
In response to GRB 070107 (Stamatikos et al. GCN Circ. 5999)
UVOT took a 100-s finding chart exposure with the White filter (160-650 nm)
starting 183 seconds after the BAT trigger, followed by a 400-s V
finding chart exposure. A second set of finding chart
exposures was obtained starting 868s post-trigger. We detect a
new variable source inside the XRT error region (Kennea et al.
GCN Circ. 6000) in the first exposure at
RA(J2000) = 10 37 36.35
DEC(J2000) = -53 12 47.5
with a 1-sigma error radius of about 1 arcsec. However, we caution
that this source is in a crowded region at low galactic latitude,
and only 4.1 arcsec from a bright V=15.9 cataloged star, which
causes the afterglow and the star to be blended in the UVOT image,
and complicates the position, magnitude, and significance estimates.
We estimate a White magnitude of ~19.5 for the new source. The source
is detected at a ~4-sigma significance level. The same source is
detected at a level of 2.7 sigma in the subsequent 400-s V finding chart.
The new source is not significant in later White and V exposures.
We note that the extinction estimate in this region (whose galactic
latitude is 4.56 degrees) is large, and uncertain.
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