Radio source calibration for the VSA and other CMB instruments at around 30 GHz

Abstract

Accurate calibration of data is essential for the current generation of CMB experiments. Using data from the Very Small Array (VSA), we describe procedures which will lead to an accuracy of 1 percent or better for experiments such as the VSA and CBI. Particular attention is paid to the stability of the receiver systems, the quality of the site and frequent observations of reference sources. At 30 GHz the careful correction for atmospheric emission and absorption is shown to be essential for achieving 1 percent precision. The sources for which a 1 percent relative flux density calibration was achieved included Cas A, Cyg A, Tau A and NGC7027 and the planets Venus, Jupiter and Saturn. A flux density, or brightness temperature in the case of the planets, was derived at 33 GHz relative to Jupiter which was adopted as the fundamental calibrator. A spectral index at ~30 GHz is given for each. Cas A,Tau A, NGC7027 and Venus were examined for variability. Cas A was found to be decreasing at $0.394\pm 0.019$ percent per year over the period March 2001 to August 2004. In the same period Tau A was decreasing at $0.22\pm 0.07$ percent per year. A survey of the published data showed that the planetary nebula NGC7027 decreased at $0.16\pm 0.04$ percent per year over the period 1967 to 2003. Venus showed an insignificant ($1.5\pm 1.3$ percent) variation with Venusian illumination. The integrated polarization of Tau A at 33 GHz was found to be $7.8\pm 0.6$ percent at pa $=148^{\circ }\pm 3^{\circ }$.}

13 pages, 15 figures, submitted to MNRAS

References in corpus (22)

• Five-Year Wilkinson Microwave Anisotropy Probe (WMAP) Observations: Data Processing, Sky Maps, and Basic Results
• Electric Dipole Radiation from Spinning Dust Grains
• Extended Mosaic Observations with the Cosmic Background Imager
• Towards a free-free template for CMB foregrounds
• High sensitivity measurements of the CMB power spectrum with the extended Very Small Array
• A determination of the Spectra of Galactic components observed by WMAP
• First Year Wilkinson Microwave Anisotropy Probe (WMAP) Observations: Beam Profiles and Window Functions
• Detection of anomalous microwave emission in the Perseus molecular cloud with the COSMOSOMAS experiment
• Five-Year Wilkinson Microwave Anisotropy Probe (WMAP)Observations: Beam Maps and Window Functions
• Morphological analysis of the cm-wave continuum in the dark cloud LDN1622
• First results from the Very Small Array -- III. The CMB power spectrum
• First results from the Very Small Array -- I. Observational methods
• Global spectral energy distribution of the Crab Nebula in the prospect of the Planck satellite polarisation calibration
• The Crab Nebula's Moving Wisps in Radio
• First results from the Very Small Array -- II. Observations of the CMB
• CBI limits on 31 GHz excess emission in southern HII regions
• An Absolute Flux Density Measurement of the Supernova Remnant Casseopia A at 32 GHz
• An upper limit on anomalous dust emission at 31 GHz in the diffuse cloud [LPH96]201.663+1.643
• Anomalous radio emission from dust in the Helix
• The Fading of Supernova Remnant Cassiopeia A from 38 MHz to 16.5 GHz from 1949 to 1999 with New Observations at 1405 MHz
• Observations of the Corona Borealis supercluster with the superextended Very Small Array: further constraints on the nature of the non-Gaussian CMB cold spot
• Maximum-likelihood astrometric geometry calibration of interferometric telescopes: application to the Very Small Array

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