  The peculiar Type Ib supernova (SN) 2006jc has been observed with the
UV/Optical Telescope (UVOT) and X-Ray Telescope (XRT) on board the Swift
observatory over a period of 19 to 183 days after the explosion. Signatures of
interaction of the outgoing SN shock with dense circumstellar material (CSM)
are detected, such as strong X-ray emission (L_{0.2-10} > E39 erg/s) and the
presence of MgII 2800A line emission visible in the UV spectra. In combination
with a Chandra observation obtained on day 40 after the explosion, the X-ray
light curve is constructed, which shows a unique rise of the X-ray emission by
a factor of ~5 over a period of ~4 months, followed by a rapid decline. We
interpret the unique X-ray and UV properties as a result of the SN shock
interacting with a shell of material that was deposited by an outburst of the
SN progenitor two years prior to the explosion. Our results are consistent with
the explosion of a Wolf-Rayet star that underwent an episodic mass ejection
qualitatively similar to those of luminous blue variable stars prior to its
explosion. This led to the formation of a dense (>E7 cm**-3) shell at a
distance of ~E16 cm from the site of the explosion, which expands with the WR
wind at a velocity of (1300+/-300) km/s.
