  We observed comet 322P/SOHO 1 (P/1999 R1) from the ground and with the
Spitzer Space Telescope when it was between 2.2 and 1.2 AU from the Sun. These
are the first observations of any SOHO-discovered periodic comet by a non-solar
observatory, and allow us to investigate its behavior under typical cometary
circumstances. 322P appeared inactive in all images. Its lightcurve suggests a
rotation period of 2.8+/-0.3 hr and has an amplitude greater than ~0.3 mag,
implying a density of at least 1000 kg m$^{-3}$, considerably higher than that
of any known comet. It has average colors of g'-r' = 0.52+/-0.04 and r'-i' =
0.04+/-0.09. We converted these to Johnson colors and found that the V-R color
is consistent with average cometary colors, but R-I is somewhat bluer; these
colors are most similar to V- and Q-type asteroids. Modeling of the optical and
IR photometry suggests it has a diameter of 150-320 m and a geometric albedo of
0.09-0.42, with diameter and albedo inversely related. Our upper limits to any
undetected coma are still consistent with a sublimation lifetime shorter than
the typical dynamical lifetimes for Jupiter Family Comets. These results
suggest that it may be of asteroidal origin and only active in the SOHO fields
of view via processes different from the volatile-driven activity of
traditional comets. If so, it has the smallest perihelion distance of any known
asteroid.
