We present results from ASCA observations of the binary CI Cam both in quiescence and in outburst in order to identify its central accreting object .
The quiescence spectrum of CI Cam consists of soft and hard components which are separated clearly at aound 2–3 keV .
A large equivalent width of an iron K \alpha emission line prefers an optically thin thermal plasma emission model to a non-thermal power-law model for the hard component , which favors a white dwarf as the accreting object , since the optically thin thermal hard X-ray emission is a common characteristic among cataclysmic variables ( binaries including an accreting white dwarf ) .
However , since the power-law model , which represents the X-ray spectrum of the soft X-ray transients in quiescence , provides with an equally good fit to the hard component statistically , we can not exclude possibilities of a neutron star or a black hole from the quiescence data .

The outburst spectrum , on the other hand , is composed of a hard component represented by a multi-temperature optically thin thermal plasma emission and of an independent soft X-ray component that appears below 1 keV intermittently on a decaying light curve of the hard component .
The spectrum of the soft component is represented well by a blackbody with the temperature of 0.07 - 0.12 keV overlaid with several K-edges associated with highly ionized oxygen .
This , together with the luminosity as high as \sim 1 \times 10 ^ { 38 } { erg s } ^ { -1 } , is similar to a super-soft source ( SSS ) .
The outburst in the hard X-ray band followed by the appearance of the soft blackbody component reminds us of recent observations of novae in outburst .
We thus assume the outburst of CI Cam is that of a nova , and obtain the distance to CI Cam to be 5–17 kpc by means of the relation between the optical decay time and the absolute magnitude .
This agrees well with a recent estimate of the distance of 5–9 kpc in the optical band .
All of these results from the outburst data prefer a white dwarf for the central object of CI Cam .