The Advanced Satellite for Cosmology and Astrophysics (ASCA)
performed a long (4.5-day) observation of MCG-6-30-15 on 1994 July 27.
The `good' exposure times were 
in each of the four
detectors. As a result, high signal-to-noise, medium-resolution X-ray
spectra were obtained in the 0.6-10keV band. The fact that the X-ray
flux is highly variable on short timescales, together with ROSAT
imaging, confirms that the observed X-rays are originating from the central
engine of this Seyfert nucleus (see Fig. 1 of Fabian et al. 1995).
Detailed analyses of these data are presented in Tanaka et al. (1995), Otani et al. (1996) and Iwasawa et al. (1996). As discussed by these authors, the 0.6-10keV X-ray spectrum shows clear deviations from the canonical power-law form. In particular, the OVII and OVIII edges from the warm absorber are prominent features in the 0.7-2keV range and a broad emission feature is seen between 5-7keV.
ASCA revealed the warm absorber in MCG-6-30-15 to be highly variable (Fabian et al. 1994; Reynolds et al. 1995; Otani et al. 1996). Detailed modeling of this variability (Otani et al. 1996; Reynolds 1996) has led to a two-zone model for this absorber. There seems to be a highly photoionized inner region (possibly related to the BLR) and a less ionized outer region (possibly related to the putative molecular torus or NLR). It is likely that both of these absorbers are in outflow driven by the radiation pressure of the central source (Reynolds & Fabian 1995).
The emission feature at 5-7keV is thought to be due to the fluorescent
K 
line emission of cold iron (i.e. FeI-FeXVII)
that results when primary X-rays illuminate cold material in the vicinity
of the central engine (George & Fabian 1991; Matt, Perola & Piro 1991).
The rest-frame energy of this emission line is 6.4keV. ASCA
resolves this line and allows its profile to be determined. It is found
that the profile is in good agreement with the hypothesis that it
originates from the innermost regions of a thin, radiatively-efficient,
accretion disk about a black hole (Tanaka et al. 1995; Fabian et al. 1995;
Iwasawa et al. 1996). Relativistic beaming, transverse Doppler shifts and
gravitational redshifts are of major importance in determining the profile
of this emission line. From the point of view of the current work, the
iron line observation is important since it constrains the geometry of the
energetically important inner accretion disk: in the innermost region, much
of the energy appears to be liberated as X-rays in an optically-thin region
near a radiatively-efficient thin accretion disk viewed at an inclination
of 
.