  We report on the spectral analysis of Circinus X-1 observed by the ASCA
satellite in March 1998 along one orbital period. The luminosity of the source
(in the 0.1-100 keV band) ranges from $2.5 \times 10^{38}$ erg s$^{-1}$ at the
periastron (orbital phase 0.01) to $1.5 \times 10^{38}$ erg s$^{-1}$ at orbital
phase 0.3. From the spectral analysis and the lightcurve we argue that Cir X-1
shows three states along the orbital evolution. The first state is at the
orbital phase interval 0.97-0.3: the luminosity becames super-Eddington and a
strong flaring activity is present. In this state a shock could form in the
inner region of the system due to the super-Eddington accretion rate, producing
an outflow of ionized matter whose observational signature could be the
prominent absorption edge at $\sim 8.7$ keV observed in the energy spectrum at
these phases. In the second state, corresponding to the orbital phase interval
between 0.3 and 0.7, the accretion rate is sub-Eddington and we observe a
weaker outflow, with smaller hydrogen column: the absorption edge is now at
$\sim 8.3$ keV with an optical depth a factor of 2.5 to 6 smaller. The third
state corresponds to the orbital phase interval 0.78-0.97. In this state the
best fit model to the spectrum requires the presence of a partial covering
component, indicating that the emission from the compact object is partially
absorbed by neutral matter, probably the atmosphere of the companion star
and/or the accreting matter from the companion.
