Planewave 20 Inch Ritchey-Chrétien Optical Tube Assembly

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Part Number: 200125Q
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Optical Design Ritchey-Chrétien (RC)
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
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
Diameter 7.5 inch (191mm)
Material Precision Annealed Borosilicate
Shape Hyperbolic
Coating Broadband AR Coatings (less than .5% reflected from 400 to 700nm)
Optical Diameter 20 inch (508 mm)
Outer Diameter 20.5 inch (521 mm)
Shape Hyperbolic
Material Precision Annealed Borosilicate or Fused Silica
Coating Enhanced Aluminum – 96%
Carbon Fiber Truss Design Minimizes thermal expansion which causes focus shift with changes in temperature
Dovetail expansion joint Allows for the difference in thermal expansion between carbon fiber and aluminum. The expansion joint allows the aluminum dovetail expand and contract without stressing the carbon fiber lower truss
Cooling Fans Three cooling fan blow out of the optical tube pulling air though the telescope and pass the primary mirror. This helps the telescope to reach thermal equilibrium quickly. The fans are conrolled by a computer if the optional Electronic Focus Accessory (EFA Kit) is purchased.
Crated Shipping Weight 291 lbs   (132.0 kg)
Crate Width 32 inch   (813 mm)
Crate Height 36 inch   (914 mm)
Crate Length 59 inch   (1,499 mm)
RONCHI SPACER This spacer sits in place of a focuser and is used for setting the primary to secondary spacing. It has an 1.25”  inner diameter and may be used with 1.25” oculars for collimation.
RONCHI OCULAR This ocular is a Ronchi screen used for setting the primary to secondary spacing.
PRIMARY MIRROR COVER  The Primary Mirror Cover protects the primary mirror.
PRINTED INSTRUCTIONS  For Collimation and Spacing
12VDC POWER SUPPLY  Provides power for the fans (Not included for European Orders)
WRENCH SET  English Hex Wrenches (European Orders Only)
(5812A35 )
Item 200125Q

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