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Proceedings Paper

LSST Telescope guider loop requirements analysis and predicted performance
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Paper Abstract

The LSST Telescope has critical requirements on tracking error to meet image quality specifications, and will require closing a guiding loop, with the telescope servo control, to meet its mission. The guider subsystem consists of eight guiding sensors located inside the science focal plane at the edge of the 3.5deg field of view. All eight sensors will be read simultaneously at a high rate, and a centroid average will be fed to the telescope and rotator servo controls, for tracking error correction. A detailed model was developed to estimate the sensors centroid noise and the resulting telescope tracking error for a given frame rate and telescope servo control system. The centroid noise depends on the photo-electron flux, seeing conditions, and guide sensor specifications. The model for the photo-electron flux takes into consideration the guide star availability at different galactic latitudes, the atmospheric extinction, the optical losses at different filter bands, the detector quantum efficiency, the integration time and the number of stars sampled. A 7-layer atmospheric model was also developed to estimate the atmospheric decorrelation between the different guide sensors due to the 3.5deg field of view, to predict both correlated and decorrelated atmospheric tip/tilt components, and to determine the trade-offs of the guider servo loop.

Paper Details

Date Published: 4 August 2010
PDF: 12 pages
Proc. SPIE 7738, Modeling, Systems Engineering, and Project Management for Astronomy IV, 77381U (4 August 2010); doi: 10.1117/12.858287
Show Author Affiliations
Michael Warner, Cerro Tololo Inter-American Observatory (Chile)
Vincent Riot, Lawrence Livermore National Lab. (United States)
Jacques Sebag, National Optical Astronomy Observatory (United States)

Published in SPIE Proceedings Vol. 7738:
Modeling, Systems Engineering, and Project Management for Astronomy IV
George Z. Angeli; Philippe Dierickx, Editor(s)

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