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Proceedings Paper

Proposed conversion of the McMath Telescope to 4.0-meter aperture for solar observations in the IR
Author(s): William Charles Livingston
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Paper Abstract

Located on a 2076 m summit in Arizona, the present all-reflective McMath optical system consists of a 2.0-m CERVIT flat mounted as a heliostat to follow the sun, a 1.6-m 86.4 m focal-length quartz concave positioned within an inclined underground tunnel, and a 1.5-m CERVIT flat which directs the image to different fixed instrument stations. The building is adequate to accommodate a 6.0-m tracking feed and a 4.0-m concave, resulting in an f/22 beam. A 4.0 m aperture is desirable for adequate flux and resolution at 12 microns where a number of Zeeman sensitive atomic lines are found, lines which are a diagnostic for solar magnetism. At 12 microns, the diffraction limit is 0.75 arcsec, and this resolution might be realized a significant fraction of time because of improved seeing at these IR wavelengths. Direct vector measurements of solar magnetic fields would become possible because effective Zeeman splitting is proportional to wavelength, both the linear and circular Stokes amplitudes are proportional to their vector field components, and instrumental polarization becomes negligible at 12 microns. The telescope would also be used at night by the solar/stellar community.

Paper Details

Date Published: 1 September 1991
PDF: 5 pages
Proc. SPIE 1494, Space Astronomical Telescopes and Instruments, (1 September 1991); doi: 10.1117/12.46747
Show Author Affiliations
William Charles Livingston, National Solar Observatory (United States)

Published in SPIE Proceedings Vol. 1494:
Space Astronomical Telescopes and Instruments
Pierre Y. Bely; James B. Breckinridge, Editor(s)

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