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The discovery by Hey, Parsons and Phillips1,2 of a variable source of radio-frequency radiation in the constellation of Cygnus suggested that at least part of the galactic radiation was due to very intense discrete sources. Afterwards a detailed study of this region was made by Bolton and Stanley3, using an interference system of greater resolving power; their results showed that the angular diameter of the source was smaller than the resolving power of their apparatus (8 minutes of arc), and the more precise determination of its position enabled them to show that the source does not coincide with any outstanding star. In a more recent note Bolton4 describes the extension of this work and the discovery of other discrete sources.

DURING mapping observations of radio source HB21 at 600 Mc/s using the new 260-ft. radio telescope1 here, a highly complex region of radio radiation was revealed between declination −49° and +51° extending from right ascension 20 h 30 m to 21 h 50 m. The region is situated about 8° north-east of the well-known radio source2 Cygnus X. The new region, like Cygnus X, contains an unusual number of separate discrete radio sources of various sizes, and will be referred to as Cygnus Y.

A RECENT radio survey of the galactic anti-centre region, made at 242 Mc./s. with the Ohio State University radio telescope, has revealed an intense extended radio source in the constellation of Monoceros. The co-ordinates of the radio source agree closely with the position of the Rosette nebula surrounding the galactic cluster NGC2244. Also the width in right ascension of the radio source is comparable with the diameter of the nebula. Thus, it is presumed that the radio source may be identified with the Rosette nebula.

THE experiments of Bolton and Stanley1, and of Ryle and Smith2,3, using a radio interferometer have shown that a significant part of the extra-terrestrial radio noise is associated with point sources with diameters of less than 6 minutes of arc. Although the majority of these sources are unidentified with visual objects, their distribution indicates that they lie in our own galaxy. Attempts to detect radio emissions from specific extra-galactic objects have hitherto been unsuccessful. In this communication we describe the results of an experiment to detect radio emissions from the Andromeda Nebula (M.31) using a narrow pencil-beam aerial and high-sensitivity receiving equipment.

IN a recent communication1 an account was given of the discovery of a number of discrete sources of galactic radio-frequency radiation. Accurate measurements of the position of three of these sources have since been made from sites on the east and west coasts of New Zealand and on the east coast of Australia. The technique employed was to observe the sources at rising or setting, with an aerial on a high cliff overlooking the sea. These observations, when corrected for atmospheric refraction, allow the path of a source above the horizon to be plotted, and the time of its rising and setting—and hence its celestial co-ordinates—to be determined.

SINCE the discovery of localized sources of extraterrestrial radio-frequency radiation in 19481, surveys have been carried out over the whole sky2,3, and the positions and intensities of about one hundred sources are now known. Although a few of these sources have been identified with extra-galactic nebulae3–5 it is generally considered that the majority must lie within the Galaxy with a distribution, and perhaps a density, similar to that of the common visual stars6. However, it has not yet been possible to associate the radio sources with any class of visual objects in the Galaxy, and in only one instance has an identification been made, namely, the identification of a source in Taurus with the Crab nebula7. As the Crab nebula is believed to be the remnant of the supernova of 1054, it is to be expected that the remnants of other supernovae are also sources of radio radiation. The other supernovae known to have occurred in the Galaxy are those of 1572 and 1604, but the published surveys show no radio source in either of these positions.