Comet C/2001 C2 (originally designated SOHO-294) was discovered in
LASCO C3 images on February 6, 2001, and has been confirmed as a member
of the Kreutz family of Sun-grazing comets. These comets are believed
to be fragments of a parent body which was torn apart some time in the
distant past. The image is a composite of LASCO C2 data, the white light
corona at 19:54 UT, and two UVCS observations of the comet itself. The
UVCS images represent observations taken at 4.82 and 3.32 solar radii
over a time span of 19:11 to 20:02 UT and 20:11 to 20:45 UT,
respectively. Each UVCS image is a time sequence of several 200
second exposures as the comet passed across the entrance aperture.
The UVCS comet images have been approximately positioned and scaled
to the LASCO corona image. A wide, well-defined tail can be seen in
the magnified version of the 4.82 solar radii observation. 

Solar radiation heats the comet which in turn causes the outgassing of
the water molecules and dust. The dust scatters sunlight at visible
wavelengths, making the comet bright in LASCO images. The water
molecules break down into oxygen and hydrogen atoms, and the hydrogen
atoms interact with the coronal plasma. The hydrogen atoms scatter
Lyman alpha (1215 Angstrom) radiation from the Sun. The UVCS images
represent the brightness at this wavelength.

Several properties of the comet and the encountered coronal environment
can be determined from this observation. The outgassing rate of water
molecules was calculated at approx. 100 kg/s and the size of the
cometary nucleus was on the order of 10 meters during the UVCS
observations. The comet also acted as a probe for the determination
of coronal conditions.  Densities of about 10,000 particles per cubic
centimeter at 4.82 solar radii, and 86,000 particles per cc at 3.32 solar
radii were found.  This sharp increase suggests that the comet passed
from a fast solar wind region to a denser slow solar wind area. All
of the results presented here are preliminary estimates.