Improved Positions and Some Optical Identifications for 451 4C Radio Sources Between Declinations 4° and 20°

Abstract

SummaryAccurate positions have been measured at Parkes for 451 40 radio sources between declinations 4° and 20°. For most of the sources the r.m.s. uncertainty is ± ION arc in each coordinate. Optical identifications are suggested for 94 sources, of which 22 are galaxies and 72 are possible quasi.stellar objects.

Some Identifications for Weak Sources in the Parkes Catalogue for Declinations +20° to ?20°

“…These observations were made at intervals of about Ii hr throughout the observing period. Pointing corrections were determined in the manner described by Merkelijn (1969) and Wills and Bolton (1969) and applied to the measured positions.. The accuracy of the present measurements is believed to be similar to that of the measurements of Merkelijn and of Wills and Bolton.…”

“…8 408 (f.u.) 3-0 2-5 3-4 3-0 1-9 2-3 3-2 2-5 2-8 2-6 2-8 2-5 2-5 2-7 2-6 3-3 3-0 3-0 3-7 2-3 2-1 5-2 5-7 2-9 3-1 4-3 3-3 2-4 3-6 4-6 6-4 Wills and Bolton (1969) and the identification has been confirmed by Wills (personal communication) from photometry. The present position is in closer agreement with that of the optical counterpart than the position given by Wills and Bolton. B.0348+17•6.…”

“…More accurate positions for the sources between declinations +4 0 and _4 0 are contained in the Parkes 2700 MHz catalogue for this zone (Wall, Shimmins, and Merkelijn 1971). Some of the weakersourc6:3 for which possible identifications had been suggested were measured by Bolton, Shimmins, and Merkelijn (1968), and many of the weaker sources between declinations +4 0 and +20 0 which are common to the 4C catalogue were reported by Wills and Bolton (1969). Finally, Merkelijn (1969) has determined accurate positions for all the weaker sources where galaxies had been noted on the Palomar Sky Survey prints within a few minutes of arc of their catalogue positions.…”