Based on observations collected at the Observatoire de Haute Provence (OHP) (France), operated by the CNRS, at the European Southern Observatory (proposals 66.B-0026; 68.B-0505), at the Loiano telescope belonging to the University of Bologna (Italy) and at the Observatorio Astronomico National de San Pedro Martir (Mexico).

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Full Tables 6-8 and full Fig. 19 (in FITS) are only available in electronic form at the CDS via anonymous ftp to cdsarc.u-strasbg.fr (130.79.128.5) or via http://cdsweb.u-strasbg.fr/cgi-bin/qcat?J/A+A/417/499

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... galaxy

Galaxies with major axis >5 arcmin were observed with the slit perpendicular to the major axis. Few galaxies with both diameters larger than the slit length were observed. However most of the light from these objects comes from a region corresponding to half the ( $\rm 25{th}~mag~arcsec^{-2}$ ) diameters quoted in Table 2, thus well within the slit length.

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... 225 objects

Including 6 additional spectra taken with the William Herschel Telescope kindly provided to us by J. M. Vilchez (VCC 324, 334, 562, 841, 848, and 2037) and 2 spectra taken from the spectral atlas of Kennicutt (1992) (VCC 355 e 1226) the total number of Virgo spectra is 233.

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... package

IRAF is the Image Analysis and Reduction Facility made available to the astronomical community by the National Optical Astronomy Observatories, which are operated by AURA, Inc., under contract with the US National Science Foundation. STSDAS is distributed by the Space Telescope Science Institute, which is operated by the Association of Universities for Research in Astronomy (AURA), Inc., under NASA contract NAS 5-26555.

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... (1958)

We have compared the $f(\lambda)$ of Lequeux et al. (1979) with the derivation of Cardelli et al. (1989), which assumes the extinction law of Seaton (1979) and of Savage & Mathis (1979). The two functions are in agreement (in the optical range of our interest): differences are $\leq$ 0.03 from [OII] to H $\alpha$ (included); 0.05 at [SII].

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... continuum

The integration has been carried in the Lick system, but the indices were not corrected using Lick standards. Notice that the EW $\rm H\beta$ listed in Table 9 do not correspond with those in Table 8 for galaxies in common between the two Tables (e.g. elliptical galaxies with $\rm H\beta$ in absorption) because they are obtained with different measuring techniques.

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