With the exception of the nonobjective mountings, the discussion in this
chapter has made Httle mention of the appropriate telescope focus for each
instrument type. Instruments of smaller size are usually used at the Cassegrain
focus,
while large-beam spectrometers are usually placed at a Nasmyth focus on a
platform that rotates with the telescope. Fiber-fed spectrometers are generally
placed on a fixed platform near the telescope.
Older telescope facilities often included a Coude room below the telescope,
with a three-mirror system redirecting the light from a Cassegrain telescope along
the polar axis ...
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