Position and Flux Density Calibration at Molonglo

Abstract

When the Molonglo Cross was brought into full operation its higher angular resolution and greater pointing accuracy posed special problems for position calibration. The development of a southern radio calibration grid is described, together with its extension for the MOST. The techniques developed in this program have found wide applicability in radio-source identification searches at other observatories. Calibration in flux density was based on absolute measurements at 408 MHz and transferred via secondary standards; at 843 MHz, the flux density calibration was based partly on absolute measurements and partly on the earlier 408 MHz data. The collection of data spanning several years led to the discovery of significant time variability at 408 MHz.