Planewave, CDK24


24 inch   (610 mm)

Focal Length

3962 mm   (155.98 inch)

Focal Ratio


Central Obstruction

47% of the Primary Mirror Diameter (11.38")

Back Focus from Mounting Surface

14.1 inch   (358 mm)

Back Focus from Racked in Hedrick Focuser (including front spacer)

5.81 inch   (148 mm)

Back Focus from Racked in IRF90 Rotating Focuser (including front spacer)

5.30 inch   (135 mm)


240 lbs   (108.9 kg)

OTA Length

56 inch   (1,422 mm)

OTA Width

31 inch   (787 mm)

OTA Height

35 inch   (889 mm)

Upper Cage

Carbon Fiber Truss

Lower Cage

Carbon Fiber Truss with Aluminum Light Shroud

Optimal Field of View

70 mm (58 arcminute)



24.5 inch   (622 mm)


24 inch   (610 mm)

Focal Ratio          



Laser Collimated and Permanently Fixed


Precision Annealed Borosilicate


Prolate Ellipsoid


Enhanced Aluminum - 96%



9.45 inch   (240 mm)


Precision Annealed Borosilicate




Enhanced Aluminum - 96%



135 mm   (5.31 inch)

Number of lenses          



Broadband AR Coatings (less than .5% reflected from 400 to 700nm)


Carbon Fiber Truss Design

Minimizes thermal expansion which causes focus shift with changes in temperature

Lower Light Shroud

Protects the primary mirror from damage and stray light

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

3.5 inch Hedrick Focuser

Heavy duty no-slip focuser. The focus tube runs on 5 bearings and is driven by a

leadscrew so there is no chance of slipping. Focus may be automated through a

computer using PlaneWave's EFA Kit add-on. The draw tube travel is 1.3 inch.

Cooling Fans

The CDK24 has two different cooling schemes. First, there are three fans behind

the primary mirror that blow air out of the optical tube pulling air though the telescope

and by the primary mirror. This helps the telescope to equilibrate quickly. Second,

there are 4 fans placed around the face of the primary mirror to equilibrate the

face of the mirror and to keep a laminar air flow above the telescope's light path.

The fans can be controlled with a manual switch on the optical tube or by a computer

if the optional Electronic Focus Accessory (EFA Kit) is purchased.

cdk24 a200 wide

Planewave, CDK24


Astro-Physics, 3600GTO

Mechanical Specification


All CNC machined aluminum bar stock, stainless steel, brass; stainless steel fasteners

Finishing and Assembly

Every part is hand-finished and inspected. All assembly is done by hand, by highly

skilled mount assembly staff.

Worm wheel - R.A./Dec.

13.0" (330 mm), 256 tooth aluminum

Worm gear - R.A./Dec.

Brass, 1.41" (35.8 mm) diameter

Axis shaft - R.A./Dec.

4.72" (120 mm) diameter with 4.02" (102 mm) clear inside diameter

Shaft axis bearings - R.A./Dec.

7.09" (180 mm) diameter deep groove ball bearings

Worm gear bearings

1.57" (40 mm) angular contact ball bearings

Latitude range

15-70 degrees

Azimuth adjustment

Approximately 14 degrees (+/- 7 degrees from center)

Counterweight shaft

2.5" (64 mm) diameter x 31.5" (800 mm) long [30" (760 mm) useable length], incl.

large machined safety stop knob. Will fit 12 optional 30 lb. (13.6 kg) counterweights.

Optional 10" (254 mm) shaft extension available.

Weight of mount

Total: 247 lb. (112.3 kg); R.A. axis/polar fork: 121 lb.lpadding="0" cellspacing="1"

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Electronic components

Rated for industrial and automotive applications


High-torque, zero-cogging Swiss DC servo motors, enclosed in machined aluminum housing

Motor encoder

2000 tic quadrature yielding an effective resolution of 0.044 arcseconds per tic

Motor reduction gear train

57.6:1 gear reduction through a custom built set of large diameter, fine-toothed, precision,

spur gears for vastly superior performance

Servo Motor Control Box

GTOCP3 Control Box, removeable

Hand-held computer

GTO Keypad to control all mount functions. Includes extensive databases and tour features

in a simple, intuitive interface. Firmware updates via the internet

Power consumption

~ 0.4 to 0.8 amps at 15 volts - tracking
~ 1.5 to 3.0 amps at 15 volts - both motors slewing at top speed of 600x

Power requirements

Nominal 15 volt DC supply at 10 amps recommended

Periodic error

5 arc seconds peak-to-peak (+/- 2.5 arc seconds) or less in one worm cycle (5.6 minutes);

native, prior to any error correction

Maximum slew speed

2.5 degrees / second


Astro-Physics, 3600GTO