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IT has been suggested recently1–4 that two classes of radio-loud extragalactic object, narrow-line radio galaxies and quasars, are intrinsically similar, differing only in the angle from which they are seen by the observer. In the simplest version of such models, one would expect that the [O III] 5,007-A line luminosities of the two types of object would be similar for a given extended radio luminosity and redshift. In spectroscopic observations of a sample of radio galaxies and quasars selected so as to be otherwise comparable, we find that this is not the case: the quasar [O III] luminosities exceed those of radio galaxies by factors of 5–10. Extinction by at least two magnitudes as a result of orientation differences is necessary for these observations to remain consistent with the radio galaxy/quasar unification hypothesis; we suggest that evidence for such extinction may exist in the form of high Hα/Hβ ratios in radio galaxies5–8.

Very long baseline interferometry (VLBI) observations of the double QSO 0957 + 561 have revealed radio fine structure in the two ‘image’ components A and B. The structures are similar, both of the ‘core–jet’ type typical of many compact extragalactic radio sources. The shapes of the images put strong constraints on the mass distribution responsible for the gravitational imaging.

The radio source 0957 + 561 has at least four components. Two coincide with the optical QSOs, which is in accordance with the hypothesis that the QSOs are images of a single object due to a gravitational lens. There are details of spectra and structure which are more difficult to reconcile with the hypothesis.

Powerful extragalactic radio sources may all be members of a single family in which those showing superluminal behaviour are the ones in which a relativistic jet is directed towards the observer. The superluminal sources are shown to have extended radio structures the form of which is consistent with such a unified scheme. This interpretation requires that the Hubble constant H0 should be nearer to 100 than to 50 km s−1 Mpc−1.

Evidence concerning the associations between QSOs and galaxies with similar redshifts, and pairs with very different redshifts is reviewed. It is concluded that both kinds of associations are likely to be real.

WE present twenty-four identifications of radio sources with neutral coloured objects of stellar appearance. We consider these objects to be of special interest because they do not fall into the two normally accepted categories for identification; that is, galaxies or blue stellar objects. Two of them have recently been found to have exceptionally high redshifts1,2, and it is hoped that further optical measurements on the others will produce equally interesting results.

IT is of fundamental importance in the study of quasars to understand whether or not their continuum emission is isotropic, because this affects the overall energy budget and can also help to distinguish between the different models proposed for their central regions1. The reported small range of emission-line equivalent widths in quasars have earlier been used to argue against a relativistically beamed or anisotropic continuum2,3. Here we use recent spectroscopic observations of 46 radio-loud quasars to show that the equivalent width of the [O III] 5,007-A emission line is strongly anticorrelated with the degree of radio core prominence R, which has been found to be a statistical indicator of orientation relative to the line of sight4–6. This observed anticorrelation shows that the quasar continuum is anisotropic and provides important evidence in favour of relativistic-beaming unified schemes4,7,8. We also show that the strength of the [O III] emission line is independent of R, consistent with unified schemes.

A VARIETY of interesting objects have been discovered in recent years within several arc min of the galactic centre. These include the main (east and west)1 components of the radio source Sgr A, a compact radio source2 at the centre of Sgr A West which may be the galactic nucleus, and a group of infrared sources3 in a region of ∼ 20″ diameter surrounding this compact radio source. In February 1975 Eyles et al.4 discovered the transient X-ray source A1742–28 near the galactic nucleus. We report here the detection of a radio transient source which we believe is very likely to be associated with this X-ray source. Although we have evidence that this transient radio source lies close to the centre of the Galaxy, it is clearly not to be identified with the nucleus itself.

Walsh et al.1 originally suggested that the double QSO 0957 + 561 A, B might be images of the same object formed by a gravitational lens because of their remarkably similar optical spectra. Additional optical spectral data2 strengthen the evidence for a gravitational lens. Radio data at 5 GHz have shown a complex structure3,4. There are compact (

WE have completed a series of observations at Jodrell Bank on the radio structures of a complete sample of QSO candidates identified from the Parkes ±4° equatorial survey. Four sources are of particular interest in that they have properties which lead us to suggest that they may be QSOs of unusually high redshift.

ELEVEN radio sources have been identified with stellar objects which, although they appear definitely blue on the Palomar Sky Survey prints, do not show the characteristic ultraviolet excess normally associated with quasistellar radio sources. The RRE Malvern interferometer1 was used to measure accurate radio positions for most of the 340 sources in the Parkes 2,700 MHz survey2, which have flux densities greater than 0.35 f.u. at 2,700 MHz. These accurate positions were used to improve the optical identifications reported by Wall et al.2.

TWO neutral-coloured stellar objects, OH471 and OQ172, have been shown to be QSOs with redshifts of 3.40 and 3.53 respectively1,2. This has stimulated interest in other radio sources identified with stellar objects which lack the ultraviolet or blue colour excesses normally associated with quasars. Browne and McEwan3 have published a list of objects which, though blue, show no ultraviolet excess; I. W. A. B., J. H. Crowther and R. L. Adgie have prepared a list (unpublished) of sources identified with neutral coloured objects, which includes both OH471 and OQ172. Sources of both types have been put forward as possible high redshift QSOs. We have measured the radio angular diameter of the sources on both lists, and of four further objects which may possibly be similar. These objects4,5, OJ287, W Com, ON235 and BL Lac, show no spectral lines but resemble OH471 and OQ172 in colour.

A 2,695 MHz survey of radio sources in a narrow strip of declination has recently been completed with the Jodrell Bank Mk II radio telescope (full details will be published later). Accurate positions for all the 74 sources have been measured with the RRE Malvern 2,695 MHz interferometer. Using these positions and a transparent overlay technique of identification the relative positions of radio and optical objects were located on the National Geographic‐Palomar Sky Survey prints with an r.m.s. error of 4 arc s. In the 24 h of right ascension covered by the survey, twenty-three identifications with stellar objects have been made; among these are two remarkably bright (14.5 magnitude) objects, separated by less than two degrees in the sky, which may be worthy of special attention. Finding charts for these two objects are shown in Fig. 1.