KPNO 2.1 Meter Telescope - Basic Parameters and Facts

Basic Optical Data

Primary Mirror
Radius of curvature 11168.4 mm concave
Conic constant -1.1065654
Mirror diameter 2133.0 mm (Drawing WISCO-30030)
Clear aperture diam 2124.0 mm
Central hole diam 635 mm
Central obscuration diam 870 mm (f/7.6 secondary baffle)
F/7.6 Secondary Mirror
Distance from primary 3885.0 mm
Radius of curvature 5186.0 mm convex
Conic constant -5.46905
Clear aperture diam 654.3 mm (CHECK)
Secondary to RC focus 4929.7 mm
Instrument rotator to RC focus 50.4 mm
Effective focal length 16200.8 mm
Plate Scale 12.69 arcsec/mm
Light-collecting area 2.950 m²
Focus Encoder 1.0 µ/unit (approx)
F/15 Secondary Mirror
Distance from primary 4583.0 mm
Radius of curvature 2453.9 mm convex
Conic constant -3.1227715
Clear aperture 374.7 mm (undersize)
Secondary to RC focus 5627.7 mm
Instrument rotator to RC focus 50.4 mm
Effective focal length 31950 mm [CHECK]
Plate Scale 6.46 arcsec/mm
f/15 cone diameter 156.4 mm
Light-collecting area 2.835 m² (cone installed)
Light-collecting area 3.114 m² (cone removed)

As Built Prescriptions

Telescope

Cassegrain Cage Mechanical Data

Component Weight(lb) Moment (in-lb)*
Instrument rotator 347 520
Guider 150 1200
Allowable instrument 500  
Total load 1000 30000

* datum=back of primary mirror cell

Optical Layout Figure

Dome

  • Lower shutter will vignette the beam for zenith distances greater than 62.3 degrees.
  • With the lower shutter raised, vignetting will occur for zenith distances less than 23 degrees

Gold Guider

Guider Field of View