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Proceedings Paper

Robust guide-star tracking algorithm proposed for Gravity Probe-B relativity mission
Author(s): Dz-Hung Gwo
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Paper Abstract

The gravity probe-B cryogenic star-tracking telescope provides the inertial pointing reference, as established by a distant guide star, with milli-arc-second resolution for the NASA/Stanford relatively gyroscope experiment. The star image of the f/27 Cassegrainian telescope is split onto two focal planes by a 50/50 intensity splitter, with each resultant image further divided by a roof prism reflector to generate the quadrant pointing information within few arc-seconds about the guide-star direction. Conventionally, the quadrant pointing information can be derived through the difference- and-sum algorithm. In this article, an alternative simple, yet robust algorithm is proposed and compared with the conventional one in the following aspects: (1) requirements on near perfect star-image division, (2) optimization in selecting null direction, (3) compensation of null-direction drift due to differential aging of photon detectors, (4) operational definitions of response sensitivity, linearity, and linear range of motion measurement, (5) robustness in system redundancy in terms of options in single-detector pointing per axis.

Paper Details

Date Published: 18 September 1997
PDF: 8 pages
Proc. SPIE 3112, Telescope Control Systems II, (18 September 1997); doi: 10.1117/12.278834
Show Author Affiliations
Dz-Hung Gwo, Stanford Univ. (United States)

Published in SPIE Proceedings Vol. 3112:
Telescope Control Systems II
Hilton Lewis, Editor(s)

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