One Centimetre Receiver Array-prototype observations of the CRATES sources at 30 GHz

TL;DR

This paper presents 30 GHz flux density measurements of 605 radio sources from the CRATES survey using the OCRA-p instrument, aiding understanding of radio source effects on CMB measurements and identifying spectral characteristics.

Contribution

First measurements of 30 GHz flux densities for CRATES sources using OCRA-p, providing valuable data for CMB studies and radio source spectral analysis.

Findings

Good agreement with WMAP and previous OCRA data for overlapping sources.

Identification of variable sources and correlation with gamma-ray flux.

Discovery of Gigahertz-peaked and inverted spectrum sources.

Abstract

Knowledge of the population of radio sources in the range ~2-200 GHz is important for understanding their effects on measurements of the Cosmic Microwave Background power spectrum. We report measurements of the 30 GHz flux densities of 605 radio sources from the Combined Radio All-sky Targeted Eight-GHz Survey (CRATES), which have been made with the One Centimetre Receiver Array prototype (OCRA-p) on the Torun 32-m telescope. The flux densities of sources that were also observed by WMAP and previous OCRA surveys are in broad agreement with those reported here, however a number of sources display intrinsic variability. We find a good correlation between the 30 GHz and Fermi gamma-ray flux densities for common sources. We examine the radio spectra of all observed sources and report a number of Gigahertz-peaked and inverted spectrum sources. These measurements will be useful for comparison to those from the Low Frequency Instrument of the Planck satellite, which will make some of its most sensitive observations in the region covered here.