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ALMA MEMO #419
THE Y+ LONG-BASELINE CONFIGURATION TO ACHIEVE HIGH RESOLUTION WITH ALMA
Angel Otárola (ESO) & Mark A. Holdaway (NRAO)
2002/04/12
The ALMA array configuration design has been split into a compact array, an extended array, and a “zoom” spiral array which aims to connect them. The currently accepted extended array is a 14 km ring around Chascón. Based on Fourier plane coverage, resolution, operations, engineering, and environmental arguments, we present an alternative to the extended configuration: a Y-shaped set of zooming configurations, which naturaly grows out of the spiral zoom configurations. This set of preliminary configurations indicates a savings of about 20 km in roads and cables, and 35 fewer pads compared to the current ring design. It has smoothly varying resolution, which permits the observer to tailor the resolution to his requirements. Reconfiguration is much smoother with the Y configuration than the 14 km diameter ring. The most extended Y configuration obtains the same resolution as the 14 km ring array. However, in order to achieve these advantages, together with the highest possible resolution for the ALMA interferometer, we need to explore the possibility of extending the Science Preserve by at least two kilometres to the west of its current western boundary.
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Last modified: 2002-04-12
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