Morgan (1958, 1959) has introduced a classification of galaxies based on
their nuclear region stellar population. Classes ``a'' and ``af''
are dominated by early-type stars. The main absorption features are the
Balmer lines, which are usually filled up by emission as these objects
invariably contain a H II region. Classes ``g'', ``gk'' and ``k'' are
dominated by a bulge of old population II stars. Intermediate classes
``f'' and ``fg'' have, in addition to a population of young stars, a faint
bulge of old stars. The old star population have similar spectra in all
classes (Bica 1988). AGN activity is exceptional in classes ``a'' and
``af'' but frequent in all other classes (Véron & Véron-Cetty 1986);
in consequence, the nuclear region of most AGNs contains a population of old
stars with many strong absorption lines which can make the line fitting
analysis rather difficult, especially for the
blue spectra. Therefore, when the absorption blend Mgib 
5175
was prominent, we subtracted a suitable fraction of the spectrum of the
elliptical galaxy NGC 5982, used as a template, to remove the old stellar
population contribution. Another elliptical, NGC 4365, was used as a template
for the red spectra, while NGC 821 was used for both the red and blue
spectra obtained in October and November 1997. All templates were observed
with the same spectral resolution as the emission-line galaxies.
Whenever
necessary, we have added a 
or 
absorption component; as,
usually, the absorption line is completely filled up by the
emission lines, we assumed its intensity to be 1.8 times the intensity
of the nearby absorption Ca I6495 line (Véron-Cetty &
Véron 1986b). Whenever a template and/or absorption component was used
in a fit, this is indicated in Table ![[*]](cross_ref_motif.gif)
which contains the line
fitting analysis results for the 53 observed galaxies.
5007/H
,
6583/H
and 6300/H respectively, and cols. 7 and 13 the
fraction of the emission
flux (respectively ) in each component with respect to the
total flux of the line in each object. A ``T'' in col. 3
(or 8) indicates that the blue (or red) spectrum has been corrected for
starlight using a suitable fraction of a template (in the blue, we have used
the elliptical galaxy NGC 5982 and in the red, the elliptical galaxy NGC 4365;
NGC 821 was used as a template for the objects observed in October and November
1997); in the same columns, an ``A'' indicates that a (or )
absorption component was added to the model. In col. 14 we give the
velocity difference between the blue and red systems, and in col. 15 the
spectroscopic classification of each component in
the model; Gaussian profiles were
used throughout, except when indicated by ``lz'' (Lorentzian profile).
Values in parenthesis have been fixed.
The line fitting analysis of the spectra was done in terms of Gaussian
components as described in Véron et al. (1980, 1981b,c). The three
emission lines, and [N II]
6548, 6583 (or and
[O III]4959, 5007)
were fitted by one or several sets of three Gaussian components;
whenever necessary, two components were added to fit the
Oi6300, 6363 lines. The width and redshift of each
component in a set were supposed to be the same. The intensity ratios
of the [N II]6548, 6583, [O III]4959, 5007 and
Oi6300, 6363 lines were taken to be
equal to 3.00, 2.96 and 3.11, respectively (Osterbrock 1974). Whenever a fit
resulted in a small negative intensity for a component, we set the
corresponding 5007/H ratio to 10, the mean value for Seyfert 2s.
All line widths given in this paper have been
corrected for the instrumental broadening. The spectra and best
fits are plotted in Fig. , the parameters describing the
individual components required by the analysis being given in Table .