A Catalog of Seyfert, Nuclei, N Systems and Active Galactic Nuclei

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Information on objects that resemble quasi-stellar objects (QSOs) such as Seyfert nuclei and N systems has been collected for many years. In classifying objects for the recently published QSO catalog, many recently discovered objects with comparatively small redshifts, which clearly resemble QSOs in as far as their continuum and line spectra are concerned, have been found. Many of the extragalactic sources found by X-ray techniques, often called Active Galactic Nuclei (AGN), fall into this category. Sometimes they are clearly parts of normal galaxies, and in other cases their environment is less clear. To look at the general properties of these phenomena, a comprehensive list of such objects is required. A catalog similar to the previous QSO catalog will be prepared. Objects to be included in the catalog must have a nucleus that is the most dominant feature and a spectrum that shows evidence of violent activity clearly not due to the evolution of normal single stars, i.e. the spectrum must show evidence for a nonthermal continuum, sometimes variable, and an emission line spectrum dominated by broad lines. The nucleus may often be a radio source or an X-ray source. As in the case for QSOs, the objects have been found by a variety of techniques: colors; morphology; low dispersion spectroscopy, including the grism-objective prism techniques; and optical studies following identification by radio or X-ray techniques. The Principal Investigator estimates that this catalogue will contain between 500 and 1000 objects. He plans to publish the catalog in 1988.