The Ultra - Compact Binary Candidate Kuv 23182 + 1007 Is a Bright

KUV 23182+1007 was identified as a blue object in the Kiso UV Survey in the 1980s. Classification-dispersion spectroscopy showed a featureless continuum except for a strong emission line in the region of He II 4686Å. This is a hallmark of the rare AM CVn class of cataclysmic variable star, so we have obtained a high-S/N blue spectrum of this object to check its classification. Instead, the spectrum shows a strong quasar-like emission line centred on 4662Å. Comparison with the SDSS quasar template spectra confirms that KUV 23182+1007 is a quasar with a redshift of z = 0.665. identified 1186 objects with blue colours in a set of fields observed using the 1.0 m Schmidt telescope of Kiso Observatory. Classification-dispersion spectroscopy of these objects were presented in a series of papers by Wegner and colleagues. The spectra of three objects, KUV 01584−0939, KUV 23182+1007 KUV 23061+1229, were given by Wegner, Boley & Swanson (1987) and Wegner & McMahan (1988). All three of these showed an interesting strong emission in the region of the He II 4686Å spectral line. However, confusion arose between the objects KUV 23182+1007 and KUV 23061+1229 in Wegner & McMahan (1988). In that work, both objects were found to have He II 4686Å emission lines (with some night-tonight variability noted), but the names in the figure titles and figure captions were in mutual disagreement. Koester et al. (2001) have since found that KUV 23061+1229 is a white dwarf of type DA. Strong He II emission is a characteristic of the rare AM CVn class of cataclysmic variable star (Warner 1995; Southworth et al., 2006). These objects are particularly interesting ultra-short period helium-rich systems which are thought to be interacting bina-ries composed of two degenerate objects, the mass donor being a helium white dwarf. KUV 01584−0939 has since been confirmed to be an AM CVn star (Warner & Woudt 2002; Espaillat et al. 2005), and is included in the General Catalogue of Variable Stars under the name ES Ceti.