VSA

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Images Courtesy of the Jodrell Bank Centre for Astrophysics

Overview

VSA (Very Small Array) was an interferometeric radio telescope operating in the Ka-band (26 - 36 GHz), purpose-built for the study of the CMB. The receivers, with their horn antennas, formed an aperture synthesis array to give the resolution of a much larger system - defined by the size of the array - but capable of simultaneously observing a much larger area of the sky than a single large antenna. VSA was installed at the Observatory on Mount Teide, Tenerife at a height of 2.5 km; the site was chosen for its low atmospheric water vapor compared to lower altitude sites in the UK.

The first set of CMB observations occurred during 2000-2001, with the VSA in the "compact array configuration". This configuation allowed determination of the CMB temperature power spectrum for multipoles 150 - 900, with sky regions and 34 GHz frequency channel both chosen to minimize foreground contamination. VSA was placed in the higher sensitivity "extended array" configuration for observations from 2001 - 2003. This configuration produced a synthesized FWHM beamwidth of ∼ 11 arcmin and covered an ℓ-range of 300 to 1500. The final delivered TT power spectrum was derived using a sky area of 82 sq deg. A total ℓ-range of 150 − 1500 was achieved by combining the complete extended array data with the earlier compact configuration data.

VSA was reconfigured to a 'super-extended' array in 2005, with a synthesized beam of 7 arcmin, and used for other studies.

Experiment Information:

• Experiment Date Range in Years: 2002 - 2004
• Frequency (GHz): 26 - 36
• l-min: 150
• l-max: 1500

The VSA website can be viewed HERE.