CFHT operating manual - Homepage Usask

CFHT Observatory Manual - Observatory (Sec.4) http://www.cfht.hawaii.edu/Instruments/ObservatoryManual/CFH...
glass plate in the optical beam in front the camera can be
tilted and its produces a displacement of the image
proportional to the small angle of the tilt.
Tip-tilt plate: fused silica
Diameter: 480 mm
Overall weight (including electronics): 55 kg
Motion amplitude: +/- 1.2 degrees (or +/- 1 arcsecond
on the focal plane)
Image correction bandwidth: up to 5 Hz
Internal loop frequency: 50 Hz
Focus Stage/Guiding Focus Sensing
The Focus Stage Assembly (FSA) is supporting the camera
and allows its motion along the optical axis in order to
accommodate the focus variation due mainly to filter
changes and temperature induced telescope dilatation. Two
guiders (GFSU) located under the top plate of the FSA give
a position and focus information from two guide stars on the
North and South edges of the MegaCam field of view.
The FSA and GFSU hardware have been designed and built
at HIA, while the the control has been designed and realized
at CFHT.
MegaCam
Focus stage
Weight of the FSA itself: 260 kg
Weight supported (camera, shutter and
cryogenics): up to 250 kg
Repeatability of the motion along the
optical axis: 0.01 mm
Motion speed: 1mm/second
Guiding/focus sensing
Limiting magnitude: ~15th magnitude
Guiding field area: 20’ x 7’ for each guider
At the heart of MegaPrime is MegaCam, a unique camera
built by the "Département d’Astrophysique, de Physique
des Particules, de Physique Nucléaire et de
l’Instrumentation Associée" at the French "Commissariat à
l’Energie Atomique" (CEA). In addition to a cryostat
housing the mosaic, and its criogenics system to maintain it
cold, CEA built the camera shutter, the filter jukebox and
the electonics to acquire the image and and send it to a
computer through fiber optics cables.
Overall mass: 350 kg
Mobile mass (moving with the FSA): 230 kg
Cryostat
Cold plate temperature: -130 degrees Celsius
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