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An image database. II. Catalogue between δ=-30deg and δ=70deg.
A preliminary list of 68.040 galaxies was built from extraction of35.841 digitized images of the Palomar Sky Survey (Paper I). For eachgalaxy, the basic parameters are obtained: coordinates, diameter, axisratio, total magnitude, position angle. On this preliminary list, weapply severe selection rules to get a catalog of 28.000 galaxies, wellidentified and well documented. For each parameter, a comparison is madewith standard measurements. The accuracy of the raw photometricparameters is quite good despite of the simplicity of the method.Without any local correction, the standard error on the total magnitudeis about 0.5 magnitude up to a total magnitude of B_T_=17. Significantsecondary effects are detected concerning the magnitudes: distance toplate center effect and air-mass effect.
| Evolution of spiral galaxies in the Virgo Cluster. I - Statistical analysis of H I deficiency and colors
A compilation of H I data and available UBV, far-UV (2421-angstrom) andH-alpha photometry is presented for 107 spiral and irregular galaxies(SO/a-Im) in the Virgo Cluster, to be compared with a reference sampleof 405 'field' galaxies. Previous findings about the H I deficiency ofVirgo Cluster spirals are confirmed. H I deficient spirals are locatedin subgroups inside Virgo I, in association with the hot gaseousintergalactic medium. (Virgo X is not H I deficient.) Early-type spiralsare more likely to be H I deficient than late-type ones and thedeficiency closely correlates with the colors through this type effect.The H-alpha + N II forbidden-line equivalent widths correlate well withthe H I contents for the Virgo Cluster spirals as well as the referencesample.
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