20-inch PlaneWave Telescopes

SBO Artemis 20-inch Telescope

We installed two 20-inch PlaneWave Telescopes (CDK20, 20-inch, 0.51 meter, f/6.8 Corrected Dall-Kirkham Astrographs) on Software Bisque Taurus 500 mounts in the spring of 2017.

The telescopes are mounted in the covered observing deck. The telescope on the west side of the deck is named Apollo and Artemis is mounted on the east pier.

The CDK20s have dual carbon-fiber truss design, with 3 cooling fans ejecting air from the back of the telescopes. The CDK20s cover a 52mm field of view without any field curvature, off-axis coma, or astigmatism.

Observing Limits

  • Artemis
    • Maximum Declination at the Meridian
      • No Obstruction:  +71.5 deg
      • 50% Obstruction: +79 deg
    • Minimum Declination at the Meridian
      • No Obstruction:  -40 deg
      • 50% Obstruction: -37 deg
  • Apollo
    • Maximum Declination at the Meridian
      • No Obstruction: 74.5 deg
      • 50% Obstruction: 82 deg

Optical System Specifications

  • Aperture: 20 inch (508 mm)
  • Focal Length: 3454 mm (135.98 inch)
  • Focal ratio: F/6.8
  • Central Obstruction: 39% of the Primary Mirror Diameter
  • Effective Collection Area is 70.41% of the B&C 24" Telescope
  • Back Focus from Racked in Focuser: 5.8 inch (147 mm)
  • Weight: 140 lbs (63.5 kg)
  • OTA Length: 47 inch (1,194 mm)
  • Upper Cage: Carbon Fiber Truss
  • Lower Cage: Carbon Fiber Truss with Carbon Fiber Light Shroud

Primary Mirror Specifications

  • Optical Diameter: 20 inch (508 mm)
  • Outer Diameter: 20.5 inch (521 mm)
  • Shape: Prolate Ellipsoid
  • Material: Precision Annealed Borosilicate or Fused SIlica
  • Coating: Enhanced Aluminum - 96%

Secondary Mirror Specifications

  • Diameter: 7.5 inch (191mm)
  • Material: Precision Annealed Borosilicate
  • Shape: Spherical
  • Coating: Enhanced Aluminum - 96%

Lens Group Specifications

  • Diameter: 90 mm (3.54 inch)
  • Number of lenses: 2
  • Coating: Broadband AR Coatings (less than .5% reflected from 400 to 700nm) 

Primary Detector

  • ZWO ASI6200MM Pro
  • Detector Size: 36mm x 24mm
  • Resolution: 9576 x 6388
  • Pixel Size: 3.76μm
  • Maximum Quantum Efficiency: 80%

Currently Installed Filters

  • Apollo (West)
    1. UV/IR Cut
    2. Sloan g'
    3. Sloan r'
    4. Sloan i'
    5. H-Alpha
    6. OIII
    7. SII
  • Artemis (East)
    1. UV/IR Cut
    2. Sloan g'
    3. Sloan r'
    4. Sloan i'
    5. H-Alpha
    6. H-Beta
    7. UHC-L / Skyglow Suppresion