Observations of OE323(4C34.13), MO758+120, and OS210(4C28.40) with the 5-km telescope


FOUR extended radio sources identified with quasars of large redshift have been observed1, they are important in defining the relationship between mean radio angular diameter and redshift and thus limiting the permissible range of q0 and cosmological evolution of the radio source population. A difficulty with such analyses is that of allowing for the variation of the physical sizes of individual sources with time, particularly if there are different types of source present in the sample. The ideal would be to restrict the analysis to a single type with a comparatively small range of the relevant properties. We have, therefore, mapped three of the four sources—those accessible to the 5-km telescope—in order to study their structures with greater angular resolution and a better beam shape. We have also re-measured the optical positions of the associated quasars from the prints of the Palomar Sky Survey. Our results remove the positional discrepancy for MO758+120 (ref. 1) and confirm the association of an optical quasar with each of the radio sources. The suggestion that the optical and radio positions of MO758+120 (ref. 3) had been accidentally interchanged seems to be incorrect, since our optical position agrees with that given by Baldwin et al.3 to within 0.25 arc s.

Access options

Rent or Buy article

Get time limited or full article access on ReadCube.


All prices are NET prices.


  1. 1

    Gearhart, M. R. & Pacht, E. Nature 266, 819–822 (1977).

  2. 2

    Riley, J. M. & Pooley, G. G. Mem. R. astr. Soc. 80, 105–137 (1975).

  3. 3

    Baldwin, J. A. et al. Astrophys. J. 206, L83–L86 (1976).

Download references

Author information



Rights and permissions

Reprints and Permissions

About this article

Cite this article

PERRYMAN, M., RYLE, M. Observations of OE323(4C34.13), MO758+120, and OS210(4C28.40) with the 5-km telescope. Nature 269, 223–224 (1977). https://doi.org/10.1038/269223a0

Download citation


By submitting a comment you agree to abide by our Terms and Community Guidelines. If you find something abusive or that does not comply with our terms or guidelines please flag it as inappropriate.