  Using the Hubble space Telescope Fine Guidance Sensor, we have measured the
trigonometric parallax of the bright cataclysmic variable 1223 Sgr. The
absolute parallax is pi(abs)= 1.96+-0.18mas, making V1223 Sgr the most distant
CV with a well-determined trigonometric parallax. This distance, a Lutz-Kelker
correction, and the previously measured extinction yield an absolute visual
high-state magnitude Mv=4.0+-0.2. We outline a model, which is consistent with
the observed spin-down of the white dwarf and provides for much of the
UV/optical emission by reverberation of X-rays. From previous X-ray and
UV/optical data, we derive an accretion luminosity Lacc=(2.6+-0.8)e34 erg/s, a
white dwarf mass M_1=0.93+-0.12Msun, and an accretion rate dot M=(1.4+-0.3)e17
g/s.
