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Telescope Performance Overview
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Caution:
some performance characteristics have yet to be determined definitively.
- Tip-tilt image quality estimates are presented as part of the observing condition
constraints. Use of wavefront sensors is assumed (see the contents list for more
details).
- Pointing, tracking and guiding, offsetting and slewing performance (e.g. precision and overheads)
have yet to be measured. The values presented are taken from the Science Requirements
Document.
- Mirror coating - a protected silver coating offers the potential for
significantly reduced emissivity in the thermal infrared and higher reflectivity at
wavelengths longer than about 400nm, compared to aluminium (see reflectance graph).
- The current primary
mirror coating is silver on Gemini South and Gemini North.
- The current secondary mirror coating is silver on Gemini South
and Gemini North.
- Chopping with the secondary mirror is capable of 2-point (a.k.a square wave)
chopping
at an arbitrary position angle on the sky, with the following constraints:
- Chop frequency: 3Hz
- Chop amplitude (on sky): 15 arcsec
- Chop duty-cycle: 87%
- Other combinations of parameters may become possible but have not been
evaluated.
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Last update June 20, 2005; Phil Puxley