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MMA Memo #153

Fitting a 12km Configuration on the Chajnantor Site

M.A. Holdaway [1], Scott M. Foster [1], K.-I. Morita [2]

April 20, 1996

Keywords: array configuration, Chajnantor, Chile, Atacama array, site topography

We present a modified version of Keto's (1992) array optimization program which finds antenna locations which most nearly produce a uniform Fourier plane coverage, subject to constraints on where the antennas can and cannot be placed. Rather than solving the abstract problem of determining a good shape for the array and then trying to fit the array shape onto a geometrically non-optimal site, we can instead seek the array shape which gives optimal Fourier plane coverage considering the details of the site. As an example, we show how a 12 km array fits onto the geometrically limiting Chajnantor site.

Antenna plane constraints, such as are present for a 12 km array on the Chajnantor site, require long (u,v) tracks, rather than a single ``snapshot'', in order to obtain good Fourier plane coverage. The array configurations we obtain from optimizing the (u,v) coverage over 4 hour tracks, for either an unconstrained antenna geometry or the constrained Chajnantor site (which has a 4 km gap which does not permit antennas), are more closely related to circles than to Reuleaux triangles. The constrained array's Fourier plane coverage is essentially as good as either the unconstrained snapshot-optimized or unconstrained 4 hour track optimized Fourier plane coverages.

[2] NRO

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Last modified: 09 December, 1999