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Proceedings Paper

Attitude intercalibration of the star imager and the spherical compact sensor magnetometer for the Oersted geomagnetic satellite mission
Author(s): Torben Risbo; Nils Olsen
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Paper Abstract

The main instrument for mapping of the Earth's magnetic field onboard the Danish geomagnetic satellite Orsted is the 'gondola' consisting of a compact spherical coil fluxgate vector magnetometer (CSC) and a star imager (SIM). The SIM gives the attitude relative to the rectascension-declination system by taking a snapshot of the sky, the CSC measures the magnetic field vector in the instrument coordinate system. The attitude relation (gondola quaternion) between the star camera system and the magnetometer system is a fundamental instrument constant to be determined by calibration with arc seconds accuracy. This intercalibration has been carried out at the geomagnetic observatory at Brorfelde, Denmark. Snapshots of the sky were taken simultaneously with measurements of the Earth's magnetic field made by the CSC magnetometer and the observatory variometer. The SIM attitude obtained in the celestial coordinate system is transformed to the local terrestrial system. The observatory magnetic field observations are transformed to the SIM coordinate system. By comparisons with the CSC readings the orthogonal transformation between the two instrument systems is determined. If the instrument assembly is turned around in the known ambient geomagnetic field the procedure is equivalent to a thin shell calibration in a test coil system, and hence the magnetometer constants can be determined, too. Results from the calibration of the Orsted magnetic instrument are presented.

Paper Details

Date Published: 28 October 1996
PDF: 9 pages
Proc. SPIE 2810, Space Sciencecraft Control and Tracking in the New Millennium, (28 October 1996); doi: 10.1117/12.255145
Show Author Affiliations
Torben Risbo, Copenhagen Univ. (Denmark)
Nils Olsen, Copenhagen Univ. (Denmark)

Published in SPIE Proceedings Vol. 2810:
Space Sciencecraft Control and Tracking in the New Millennium
E. Kane Casani; Mark A. Vander Does, Editor(s)

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