Recognition and classification of galaxies with optical jets.

Deep images and spectra are presented for galaxies reported in various catalogs to have jets, as well as in a search of the SRC J survey plates in a region near the south galactic pole. Most of these are shown to be superpositions, polar rings, tidal features, or artifacts of the original plate material. Examples are shown of ten ways that false jets can be produced, with more detailed case studies for several systems. Based on this experience, several criteria for the brightness, location, and symmetry of genuine optical jets are suggested, which should yield survey samples much less contaminated by 'false alarms' than existing ones. Among the objects that remain as optical-jet candidates, ESO 0610-23 shows a linear, radial chain of H II regions on the outskirts of an amorphous system with complex internal structure, UGC 3995 is a close pair of spirals, one of which has a type 2 Seyfert nucleus and apparent knotty jet, and NGC 1598 has the radial features previously reported, but considerable chaotic outer structure as well. Several systems (such as AM 0207-49 and ESO 2330-38) illustrate the intrinsic difficulty of separating jets and tidal tails on morphological grounds alone in certain cases.