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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.
| Double galaxy investigations. III - The differential redshift distribution and emission-line correlations
The distribution of redshift differences for a sample of 250 closedouble galaxies is shown to depend strongly upon the emission propertiesof the component galaxies and to some extent upon interactionmorphology. The distribution is not significantly dependent either uponphysical or angular separation or upon the magnitude differential. TheDelta-V distribution can be decomposed into a sharply peaked componentwith dispersion about 100 km/s characterized by emission objects, and abroad component with dispersion about 300 km/s characterized byabsorption spectra. Within these two components, especially the sharplypeaked one, there appears to be a dependence of emission strength, andto a lesser extent interaction morphology, upon physical separation inthe range 5-20 kpc.
| Double galaxy investigations. I - Observations
Redshift information from 240 A/mm spectrograms is presented for 370double arcsec galaxy systems from the Karachentsev (1972) catalog,including all pairs in that catalog with separation less than 80 arcsec.An extensive error discussion utilizing internal and external (21 cm)comparisons provides calibration of systematic error and determines theuncertainty for a typical high weight optical redshift to be plus orminus 65 km/sec. Internal differential redshifts within single spectrausing common lines achieve accuracies of 18-30 km/sec, depending uponseparation, and are available for about 200 pairs. Extensive informationon emission and other properties is also provided.
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