Abstract
THE most extensive lists of radio sources have been compiled from surveys at frequencies below 1.5 GHz. Observations1,2 of some of these sources at 8 GHz (3.8 cm) have revealed the existence of a class of extragalactic sources with upturning or inverted spectra, indicating the presence of separate high-frequency components within the sources. The extragalactic sources which vary in flux density3,4 and polarization5,6 are found among this class of objects. These sources have also been discussed7–9 as a possible explanation of the microwave background radiation.
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BRANDIE, G. Physical Science: Excess Surface Density of Extragalactic Radio Sources at 8 GHz. Nature 225, 352–353 (1970). https://doi.org/10.1038/225352a0
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DOI: https://doi.org/10.1038/225352a0
