Investigations of the optical fields of 3CR radio sources to faint limiting magnitudes - IV

Abstract

A deep optical survey of the fields of 18 3CR radio sources has been carried out with the Hale 5-m telescope, using a prototype charged coupled device as a detector. These sources were among the few 3CR objects which were either previously unidentified or associated with very faint images at the plate limit for which confirmation was required. Ten new identifications are proposed (3C 65, 3C 68.2, 3C 175.1, 3C 239, 3C 241, 3C 267, 3C 272, 3C 289, 3C 469.1 and 3C 470), and candidates for the remaining eight sources are confirmed (3C 34, 3C 61.1, 3C 184, 3C 220.3, 3C 250, 3C 280, 3C 324, 3C 368). Of these identifications, those for 3C 68.2, 3C 175.1, 3C 250 and 3C 470 are considered provisional, since they are displaced from the radio source axes. In addition, the candidate for the 3C 61.1 is classed as a confirmed identification, although the optical field is crowded and an unambiguous identification cannot be made on positional arguments alone. A subsample of 60 sources from the 3CR catalogue, considered by previous workers, is now (provisionally) completely identified. These new results are used to construct luminosity distributions at S(l78) ≥ 20 Jy and S(178)≥ l0Jy, and the implications of the complete identification rate for models of source evolution formulated by other workers are examined.

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