NOAO >   KPNO Home >   KPNO Mountain >   2.1 Meter Parameters

Small NOAO Logo

Kitt Peak National Observatory


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)
  • Download 2.1-m f/8 ZEMAX file
  • 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)
  • Download 2.1-m f/15 ZEMAX file
  • As Built Prescriptions

    Telescope

    Cassegrain Cage Mechanical Data
    * datum=back of primary mirror cell
    ComponentWeight(lb)Moment (in-lb)*
    Instrument rotator 347 520
    Guider 150 1200
    Allowable instrument 500  
    Total load 1000 30000

    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

    NOAO >   KPNO Home >   KPNO Mountain >   2.1 Meter Parameters

    questions about this website: kpno@noao.edu