An Accurate Flux Density Scale from 50 MHz to 50 GHz

TL;DR

This paper extends the flux density scale from 50 MHz to 50 GHz using recent VLA observations, providing polynomial expressions for 20 sources with 3-5% accuracy and corrections to previous scales.

Contribution

It introduces an extended flux density scale from 50 MHz to 50 GHz based on new VLA data and updates previous standards with improved accuracy and corrections.

Findings

Flux density scale extended down to 50 MHz.

Polynomial expressions for 20 sources provided.

Scale accuracy limited to 3-5%.

Abstract

The flux density scale of Perley and Butler (2013) is extended downwards to ~50 MHz by utilizing recent observations with the Karl G. Jansky Very Large Array (VLA) of 20 sources between 220 MHz and 48.1 GHz, and legacy VLA observations at 73.8 MHz. The derived spectral flux densities are placed on an absolute scale by utilizing the Baars et al. (1977) values of Cygnus A (3C405) for frequencies below 2 GHz, and the Mars-based polynomials for 3C286, 3C295, and 3C196 from Perley and Butler (2013) above 2 GHz. Polynomial expressions are presented for all 20 sources, with accuracy limited by the primary standards to 3 -- 5% over the entire frequency range. Corrections to the scales proposed by Perley and Butler (2013) and by Scaife and Heald (2012) are given.