Radio source counts at 30 GHz

Abstract

We observe 1,377 NVSS point sources with the Green Bank Telescope (GBT) and Caltech Continuum Backend (CCB) at 31.25 GHz. We find the GBT+CCB provides 0.500 mJy rms sensitivity and a 28 arcsec FWHM beam in a 3.5 GHz band centered on 31.25 GHz. We combine these data with observations of 2,225 point sources by the Owens Valley Radio Observatory 40 m (rms sensitivity 2.5 mJy) to provide the most accurate present determination of the contribution of point sources to 1 cm wavelength cosmic microwave background measurements at small scales (< 5 arcmin). Point sources are the most significant contaminant of this signal, which is expected to be dominated by the Sunyaev-Zel'dovich effect from large galaxy clusters, and has been thus far hinted at, but not yet confirmed by, the Cosmic Background Imager.

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