BZ Camelopardalis during its 1999/2000 optical low state

We report optical observations of the VY Scl star BZ Cam during its previou s optical low state in 1999/2000. We find drastic variations in the line pr ofiles. Narrow-band imaging observations show that its nebula extends farth er than previously known and seems to be composed of two components. We det ermine the [OIII] line intensity of BZ Cam's nebula to 4.8x10(-13) erg/cm(2 )/s. We discover a proper motion of BZ Cam of 25 +/-2 mas/yr which together with the systemic radial velocity yields a space velocity of 125 km s(-1). We re-interpret the nebula as being photo-ionized by hypothesized transien t, luminous, supersoft X-ray emission during optical low states, and shaped by the transverse motion of BZ Cam.