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Proceedings Paper

Telescope design study for the NASA stratospheric observatory for infrared astronomy (SOFIA)
Author(s): George W. Sutton
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Paper Abstract

A conceptual design study was performed for the proposed "SOFIA" project, which is a 2.5+ meter primary telescope to bemounted in an open port on the side of a Boeing 747 aircraft, aft of the wing. Among the requirements are pointing stabilityof 0.14" per axis and a blur circle of 1.5" for the telescope in the visible portion of the spectrum. The wavelength band isfrom 0.3 µm to 1600 Rm. The telescope is to be a Nasmyth type so that the instrument package extends into the pressurizedcabin for easy access to the experimenter. The designs studied included a centered bearing telescope, a dumbbellconfiguration similar to the Kuiper Airborne Observatory, and an off-axis configuration with no obscuration. Both attachedand unattached Nasmyth tubes were considered. The latter requires an articulated tertiary, so scan noise was calculated. Anonlinear tracking model was used to determine the closed loop pointing stability. Observable star magnitudes werecalculated. A survey of primary mirrors was performed, with the spin-cast borosilicate honeycomb sandwich mirror havingthe best overall qualities. The remaining major issues were identified, including fabricating the air bearing and a laboratorydemonstration of the pointing stability in the presence of the aircraft vibration spectra.

Paper Details

Date Published: 30 November 2017
PDF: 2 pages
Proc. SPIE 2104, 18th International Conference on Infrared and Millimeter Waves, 21048I (30 November 2017); doi: 10.1117/12.2298738
Show Author Affiliations
George W. Sutton, Kaman Aerospace Co. (United States)

Published in SPIE Proceedings Vol. 2104:
18th International Conference on Infrared and Millimeter Waves
James R. Birch; Terence J. Parker, Editor(s)

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