Precise Measurement of the Flux Densities of the Radio Sources Cas A and Cyg A at Metre Wavelengths

Abstract

The flux densities of Cas A and Cyg A have been measured at 38.0, 81.5 and 152.0 MHz with estimated errors of less than 4 per cent, a substantial improvement in accuracy over previous determinations in this frequency range. Results are also presented for Tau A at 81.5 and 152.0 MHz. A comparison with flux densities measured at higher frequencies shows that Cas A has a constant spectral index of 0.770 ± 0.006 between 38.0 MHz and 15.5 GHz.