Measuring and Correcting Wind-Induced Pointing Errors of the Green Bank Telescope Using an Optical Quadrant Detector

Paul Ries; Todd R. Hunter; Kim T. Constantikes; Joseph J. Brandt; Frank D. Ghigo; Brian S. Mason; Richard M. Prestage; Jason Ray; Frederic R. Schwab

doi:10.1086/660677

arXiv · 1104.1593

Measuring and Correcting Wind-Induced Pointing Errors of the Green Bank Telescope Using an Optical Quadrant Detector

Paul Ries·Todd R. Hunter·Kim T. Constantikes·Joseph J. Brandt·Frank D. Ghigo·Brian S. Mason·Richard M. Prestage·Jason Ray·Frederic R. Schwab

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Abstract

Wind-induced pointing errors are a serious concern for large-aperture high-frequency radio telescopes. In this paper, we describe the implementation of an optical quadrant detector instrument that can detect and provide a correction signal for wind-induced pointing errors on the 100m diameter Green Bank Telescope (GBT). The instrument was calibrated using a combination of astronomical measurements and metrology. We find that the main wind-induced pointing errors on time scales of minutes are caused by the feedarm being blown along the direction of the wind vector. We also find that wind-induced structural excitation is virtually non-existent. We have implemented offline software to apply pointing corrections to the data from imaging instruments such as the MUSTANG 3.3 mm bolometer array, which can recover ~70% of sensitivity lost due to wind-induced pointing errors. We have also performed preliminary tests that show great promise for correcting these pointing errors in real-time using the telescope's subreflector servo system in combination with the quadrant detector signal.

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BibTeX RIS

Paul Ries, Todd R. Hunter, Kim T. Constantikes, Joseph J. Brandt, Frank D. Ghigo, Brian S. Mason, Richard M. Prestage, Jason Ray, Frederic R. Schwab. 2011-04-08. Measuring and Correcting Wind-Induced Pointing Errors of the Green Bank Telescope Using an Optical Quadrant Detector. https://doi.org/10.1086/660677

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