A Fluctuating Celestial Radio Source at 242 Megacycles per Second

Abstract

DURING our recent radio mapping survey at 242 Mc./sec. of the region near the antigalactic centre, we have detected a fluctuating radio source. The fluctuations appear similar to the scintillations observed at lower frequencies as caused by the ionosphere¹. No scintillation or fluctuation effect had been observed by us on any source in all our previous observing at or near 242 Mc./sec. Accordingly, this source was regarded with great interest, since it appeared likely that scintillations at this frequency and at a high altitude (about 60°) might mean that the source was of very small angular extent, or at least smaller than the sources having scintillation at lower frequencies and smaller than any other source we have detected. In other words, the source may be of stellar dimensions, that is, a true radio star. Although the fluctuations may be due to scintillations, there is also evidence that the fluctuations may represent variations in the intensity of the source itself.