Smithsonian Astrophysical Observatory
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As a research institute of the Smithsonian Institution, the Smithsonian Astrophysical Observatory (SAO) is headquartered in Cambridge, MA, where it is joined with the Harvard College Observatory (HCO) to form the Harvard-Smithsonian Center for Astrophysics (CfA). More than 300 scientists at the CfA are engaged in a broad program of research in astronomy, astrophysics, earth and space sciences, and science education.

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SMA Optical Guidescope

The new optical guidescope consists of a Celestron-90 spotting scope, with diameter 90mm and focal length 1000mm. The CCD camera is an Electrim EDC1000N with 7.4 micron square pixels and 8-bit electron wells. Each pixel subtends 1.526 arcseconds on the sky. In comparison, at a wavelength of 500nm, the telescope can deliver an angular resolution (1.22lambda/D) of 1.39 arcseconds. Thus the camera will undersample the diffraction pattern (in most weather conditions). The camera is controlled by a diskless PC/104 80486-based computer running Redhat 6.2 Linux. Commands arrive via Ethernet (RPC) and the subsequent images acquired are relayed via an NFS-mounted disk. A small circuit board provides an interface between the CS82C55 port on the PC/104 computer and the focus motor and encoder package. All these components are housed in an aluminum tube with an optical flat, O-rings, and hermetically-sealed connectors. Temperature and relative humidity sensors are mounted inside the enclosure.

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Last modified: Fri Feb 16 13:41:51 2007