Study of a field in the Coma supercluster. I. Automatedgalaxies count.

The existence of a filament of galaxies was shown by Fontanelli (1984) in the Coma cluster region. This paper concerns the study of a IIIaJ Palomar Schmidt plate of the Eastern end of this filament. We have developed a real time reduction technique, quite similar to that used for the COSMOS machine and performed, in real time, an image segmentation. The galaxy selection was made using a classical Bayesian classification based on the diagram of the integrated density versus the area. All the non-stellar objects were thus identified using the PDS and a morphological type was attributed to the galaxies. Our catalogue gives coordinates, magnitudes (derived from the Zwicky et al. (1961-68) and Nilson (1973) catalogues), area in pixels, and morphological types for 7582 galaxies. A histogram of all the galaxy magnitudes shows that the catalogue is apparently complete down to about the 19th magnitude. The asymmetry in the distribution of the bright objects between the North-West and the South-East part of the plate found by Fontanelli (1984) is also present for the fainter objects of our catalogue. We have identified galaxy condensations using an image segmentation on the galaxy density map. The parameters, position, axis, and orientation of these condensations have been estimated.