ASA AZ800 Alt-Az Telescope

ASA AZ800 Alt-Az Telescope


The ASA AZ800 is an azimuth mounted 0.8 meter telescope with Nasymth focus.

AZ800 Features

  • Optic design by Dipl.-Phys. Philipp Keller
  • Ritchey-Chrétien f/7 or Harmer Wynne f/5 optics
  • Quartz glass optics by ASA
  • ASA field flattener or ASA reducer with corrected field >100 mm (optional)
  • Absolute encoders on all axes
  • Motorized switch between multiple Nasmyth ports
  • Motorized primary mirror cover
  • Motorized secondary mirror focusing
  • ASA Direct Drive technology
  • Suitable for remote observing
  • Manufactured with the latest CNC technology in conjunction with high strength carbon fiber
  • Compact size with a moderate weight of 800 kg (1,765 lb.)
  • Heavy equipment can be loaded on both Nasmyth without changing the center of gravity

AZ800 Benefits

Compact Size: The azimuth design allows a very compact telescope, fitting in smaller domes compared to an equatorial telescope.

User Friendly: The Nasmyth focal point can be switched between the left and the right focus side by a mouse click within a few seconds. A direct drive motor in combination with a 0.1 arc second encoder and reference switch is used to turn the tertiary mirror. You could use one focus for visual observations while leaving your CCD camera installed on the other side. If you want to take an image of that object, all it takes is a mouse click. Of course you could also use 2 different CCD cameras, one installed with a ASA reducer for wide field imaging, the other one with a barlow lens for planetary work. Since all accessories are mounted in the center of gravity, there is no change in telescope balance when something is mounted or removed on the Nasmyth-Focus. Since there is also no focuser directly at the focus (focusing for both foci is done with the secondary), the weight of the CCD or accessories can be very heavy. The comfort in visual observing is stunning compared to a classical Alt-Az or an equatorial telescope because with the Nasmyth design the focus position and thus the view point is always at the same height.

Precise: With the AZ800 we have reached a new dimension of pointing and tracking accuracy. This is done with the direct drive and an ultra high resolution encoder with a readout of better than 1/100 arc second directly on the telescope axis. Zero backlash, zero periodic error. ASA has sold more direct drive mounts than any other telescope manufacturer. The azimuth design is also supporting overall better accuracies compared the equatorial telescopes because hysteresis effects, caused by optic shifts can be avoided. The ASA derotator is correcting the field rotation that is existent in Alt-Az telescopes. Even with 8m focal length, seeing limited exposures without any autoguiding is five minutes or more.

Perfect Optics: When it comes to optics, ASA doesn’t compromise. The optics are Harmer Wynne or Ritchey-Chrétien with optional correctors.


Starting at $200,000
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Item Number: Cassegrain: AZ800CA-TR; Ritchey-Chrétien: AZ800RC-TR

Aperture: 800 mm (31.50 inch)

Focal Length: Cassegrain: 7200mm (283.46 inch); Ritchey-Chrétien: 6400mm (251.97 inch)

Focal ratio: Cassegrain: f9; Ritchey-Chrétien: f8

Back Focus: 250 mm (9.84 inch)

Field of View: Cassegrain: 38 arc mins; Ritchey-Chrétien: 43 arc mins

Image Quality: 1.8 micron RMS spots [25mm on-axis] (400 to 900nm) 4.4 micron RMS spots [21mm off-axis] (400 to 900nm) 6.8 micron RMS spots [35mm off-axis] (400 to 900nm) (Spot and Diffraction Diagrams)

Mechanical Specs

Material: High-end Aluminum parts and carbon fiber

Workmanship: CNC Manufactured

Fork: U-shaped fork with high stiffness

Primary Mirror Blank Spec

Optical Diameter: 800 mm (31.50 inch)

Mirror Diameter: 815 mm (32.09 inch)

Material: AstroSitall

Coating: Al+SiO2 with 91% Reflectivity

Surface Quality: L/8 PtV Wavefront >95 strehl

Thickness: 90mm (3.54 inch)

Cell: 18 point floating

Secondary Mirror Blank Spec

Optical Diameter: Cassegrain: 250mm (9.84 inch); Ritchey-Chrétien: 287mm (11.30 inch)

Mirror Diameter: Cassegrain: 256mm (10.08 inch); Ritchey-Chrétien: 293mm (11.54 inch)

Material: AstroSitall

Coating: Al+SiO2 with 91% Reflectivity

Thickness: 40 mm (1.57 inches)

Third Mirror Spec

Optical Diameter: 150 mm (5.91 inches) on the minor axis with 97% Reflectivity

Thickness: 21 mm

Motor and Encoder

Azimuth Motor: ASA Direct Drive Motor

Altitude Motor: ASA Direct Drive Motor

Encoder: High resolution Renishaw encoder

Motor Torque: Ca. 120 Nm

Control Software: Autoslew — ASCOM compatible; Pointing model calculates all repetable faults; Extremly accurate tracking without external guiding; Very accurate Positioning; Automated motor tuning; Home position; 2 Park positions.

ASA Software: Sequence — MLPT for local pointing models; Auto created pointing models.

System Performance

Voltage: 24 V

Tracking Power Consumption: 0.5 - 4 amps

Absolute Current Peak: 15 amps

Pointing: < 8" RMS with Pointing File

Tracking Accuracy: < 0.25" RMS in 5 minutes

Encoder Resolution: 0.007" on the Axis

Moving Speed: 13°/sec

Cooler: Computer controlled fans

Focuser: Computer controlled motorized secondary mirror focuser

Baffle: Main mirror baffle