CFHT operating manual - Homepage Usask

CFHT Observatory Manual - Observatory (Sec.4) http://www.cfht.hawaii.edu/Instruments/ObservatoryManual/CFH...
The optical configurations are altered by interchanging three upper
ends:
Prime Focus and Coudé
Cassegrain f/8 (CAFE - fiber fed Coudé operates in the Cassegrain configuration)
Cassegrain f/35 (infrared) - This focus is no longer available (Decommissioned in
2000)
Interchange takes at least 3 hours and cannot be done at
night.
While observing, the dome slit is aligned automatically with respect to the telescope. The shutter is
normally fully opened during
the night but can be closed partially to reduce wind loads. A windscreen can also be raised.
Observers are warned that dome
rotation is quite slow, with a maximum speed of 45 degrees per minute of time.
The telescope area is maintained at the proper temperature by a chilled floor system. The floor
cooling normally operates
24 hours a day. It will be shut down, however, during summit storms and takes roughly a day to
stabilize once turned back on.
Experience has shown that the seeing is degraded if the floor cooling is shut off. Alternatively,
during high humidity conditions, the
floor cooling can cause severe icing, detrimental to electronic equipment and optics.
The telescope is controlled during the night by the Observing Assistant (or OA) only. This
includes all aspects of telescope
opertation, support systems (computer, electronic, and mechanical), and telescope orientation,
slewing and guiding on the field
requested by the observer.
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