  RBS (Rosat Bright Source) 0490 is a cataclysmic variable star (CV) with
unusually strong emission lines. The strength of the emission lines led to a
suggestion that the object is intrinsically faint and correspondingly nearby
(approx. 33 pc), which, if true, would strongly affect estimates of the CV
space density. Here we report astrometry, filter photometry, and time-series
spectroscopy of this object. The astrometry gives an absolute parallax pi(abs)
= 4.5 +- 1.5 mas and a relative proper motion of 102 mas/yr. A Bayesian
procedure gives a very uncertain distance estimate of d approx. 300 pc, and the
small parallax alone implies d > 133 pc (at two standard deviations). The mean
V magnitude is 17.4, which implies M_V = 10.9 - 5 log (d/200 pc), neglecting
extinction. At 200 pc, the space velocity would be over 90 km/s with respect to
the LSR. The time-series spectroscopy shows a possible emission-line
radial-velocity period near 46 min. This would be unusually short for an
orbital period and it may represent some other clock in the system.
