Astro-Physics Mach2GTO Mount (various versions available)

More Views

Images uploaded by Customers

No customer Image uploads yet. Add Your Review with Images
Astro-Physics Mach2GTO Mount (various versions available)

Please choose product variant below to see price and SKU number

Regular Price: € 16,750.00

Special Price Incl. Tax: € 14,237.50

Price excl. German VAT tax (19%): € 11,964.29

  • German Equatorial Mount with brushless Micro-step Servo System and
  • Renishaw Absolute Encoder for the ultimate in precise tracking
  • Precision-Adjust Rotating Pier Base / Hi-Res Azimuth Adjuster
  • Ideal for 6-7” refractors, 8-12” SCTs and Maks
  • With GTOCP5 Control System and Auto-Adjusting Motor/Gearboxes
  • Extended Temperature option available - various versions at the dropdown below
  • Astro-Physics GTO Keypad with Keypad Protector for all GTO-Mounts (optional) (#1401200 , € 1300,-) available
Important note: This product is not available online. If you are interested, please send us a formal inquiry incl. contact data by email. We shall gladly provide a detailed offer.

* Required Fields

Regular Price: € 16,750.00

Special Price Incl. Tax: € 14,237.50

Price excl. German VAT tax (19%): € 11,964.29

Product Questions and Answers

No questions yet. Be the first to ask a question about this product - it will be answered by other customers or an Admin.


Astro-Physics Mach2 GTO Universal Robotic Mount

Astro Physics’ Mach2 GTO Universal Robotic mount sets a new standard for portable telescope mounts. The mount is remarkably easy to use and quiet in operation. The Mach 2 GTO replaces the long proven Mach 1 GTO of Astro-Physics.

Universal Robotic means that Mach2 fulfills all of the requirements of a robotic mount for automated operation for imaging, satellite tracking, comet tracking, star survey work and others.

This advanced equatorial mount features Renishaw Absolute Encoders, brushless dual servo motors and the GTOCP5 Servo Control System for a seamlessly accurate mount. In addition, the clutches allow it to be used manually for star sweeping. It is so easy to use that it can be set up quickly in the field with minimal effort and no complicated startup routines. The encoders keep track of the axis positions at all times whether parked, unparked, power on or power off.


  • Renishaw Absolute Encoder for the ultimate in precise tracking - no SDE or random errors above 1/4 arc sec. Extended Temperature option available.
  • Absolute encoder provides near zero tracking error and resists outside influences such as wind and cable drag
  • Precision balancing via the clutches without taking the worm gears out of mesh
  • Brushless Micro-step Servo System for precise and whisper-quiet slewing and tracking
  • Dual-model pointing and tracking rate correction even with the telescope in the counterweight UP position. using Astro-Physics Command Center (APCC) in der Pro version, included
  • Custom tracking rates in both axes (for asteroids, comets, satellites)
  • Auto-Adjusting gear mesh
  • Image all night without meridian flip, as long as your scope clears
  • Daytime polar alignment is now simplified since we have encoders to set the positions
  • Precision azimuth adjuster with rotating base
  • Built-in bubble level
  • Right-angle polar alignment scope (optional)
  • Internal USB 3.0 cable
  • Fully supported enhanced ASCOM driver
  • Threaded for QHY Polemaster AP900 adapter
  • Portable – under 42 lbs
  • Operate with 12V battery or up to 24V power supply
  • Ideal for 6-7” refractors, 8-12” SCTs and Maks

GTO CP5 Control System

Astro-Physics has developed a new control system which combines the precision performance of the Renishaw Resolute Absolute Encoder with the whisper-quiet motion of brushless micro-step servo motors to produce a very accurate observatory-grade mount that can also be set up in just a few minutes in the field. The mount can be operated manually via the clutches or electronically with the encoder loop providing the pointing and tracking functions.

  • Use of Absolute Encoders means that the mount always knows where the axes are pointing and don't need to establish home on power-up.
  • The mount can be operated manually via the clutches or in full GoTo mode via keypad or external software.
  • Absolute Encoders are extrememly accurate in slewing, pointing, tracking, guiding. Periodic error and backlash, reversal delays in Dec are eliminated.
  • Rapid feed-forward servo loop stiffens the axes against outside disturbances such as cable drag and wind loading.
  • Both axes can be run at custom tracking rates from sub-arc second motions per hour to 1000x sidereal.
  • The GTOCP5 brushless servo system can be run from 12 volts to 24 volts with max slewing from 1200X (5 deg/sec) to 1800X (7.5 deg/sec).
  • The power to the motors is self-limiting and cannot cause any kind of damage to the windings or the electronics, even when in a stalled state.

Mach2 GTO and Renishaw Absolute Encoders

Mach2 Tracking Performance with Absolute Encoders - PE = 0.21 arc seconds

Mach2 Tracking Performance with Absolute Encoders - PE = 0.21 arc seconds

All of Astro-Physics GTO-1100 und GTO-1600 Mounts with Absolute Encoders have always used the Renishaw Resolute Absolute Encoders for precise positioning and tracking.

General Information about the Renishaw absolute encoder in our mounts

Lab Certified Accuracy! 
The Renishaw encoder accuracy is verified against a laboratory standard. Each ring comes certified with its own calibration measurement. The maximum guaranteed error on these rings translates to less than 1/2 arc second per hour tracking error.

Highest Resolution for Unparalleled Tracking Accuracy!
The Renishaw Resolute read-head interpolates a special barcode that is engraved on the matching stainless steel ring into 67 million individual addresses. Every address is unique and fully reproducible down to sub-arc second levels. This is not possible with any relative encoder system.

Ripple and Resonances – NOT with Astro-Physics!! 
Relative encoders use a simple ring that has engraved marks with separations on the order of 60 to 100 arc seconds between ticks. In order to achieve sub-arc second resolution, the gaps between these marks are filled in electronically by a method known as interpolation. Even the best interpolation methods have errors on the order of 5% (3 to 5 arc seconds). When used in a telescope drive system these relative encoders introduce a fast moving ripple in the RA tracking rate of 3 to 5 arc seconds, although the average or RMS value of this error can be quite low.

These peak excursions cause stars to move slightly back and forth in the RA direction during sidereal tracking. This tracking ripple can remain hidden when imaging with short wide-field scopes, but will manifest itself when using long focus instruments for high resolution work. It is generally a fast moving error, so it cannot be guided out.

No Sub-divisional Error! 
Because of the ever present interpolation error (SDE) with low cost relative encoders, we decided long ago that we would not use them for tracking. Renishaw absolute encoders use a different type of interpolation system that smooths out the SDE to a level that is not detectable. There is no mechanism for a relative encoder to remove the SDE.

Never Needs Homing. Simply Polar Align; Power Up; and GO!! 
An absolute encoder never needs to be homed. It is always home the minute power is applied. It always knows where it is and transmits the exact shaft position to the control box at all times.

Dependability to Astro-Physics Standards!
We have used Renishaw encoders for many years on our larger mounts, both in portable setups and in observatory remote installations. They have been totally reliable. Renishaw encoders are also considered to be the gold standard in the machine tool and robotics industries where precision is required. Yes, they are much more expensive than a simple relative encoder, but for the type of accuracy required in a telescope mount, there is nothing out there that comes close. We know, we have been evaluating options for years.

Benefits of Absolute Encoder

The utility of absolute encoders varies from brand to brand. Some manufacturers make very limited use of encoders and use relative (not absolute) encoders to provide a potential benefit to tracking and nothing else. In regards to premium mounts, assuming dual on-axis absolute encoders, the benefits may be:

  • The mount always knows where it is pointed regardless of power loss, movement of the axes when the power is off, bumping the mount or wind movement. 
  • Homing positions can be set to whatever orientation a user wants, without limitation.
  • No rehoming is required for remote locations should there be a power loss.
  • Periodic error is fully corrected. No need for occasional PE measurement curves.
  • Zero backlash in both axes for precision guiding.
  • Dual axis absolute encoders allow for variable tracking that automatically adjusts for refraction parameters.
  • Very accurate pointing makes it easy to find very faint objects.
  • Very precise tracking such that unguided imaging may be accomplished with an appropriate optical/imaging setup.
  • Very precise guiding, if needed, with instant response in both axes.  Guiding is only needed to correct for optical/imaging train issues, not mount issues.
  • Corrects for polar misalignment and repeatable mechanical flexures.
  • Very precise dual-axis tracking is very important for high precision tracking on objects like comets, asteroids, artificial satellites, where the mounts use a "self-guiding" function based on orbital elements.

We invite you to review the additional technical information regarding the encoders to find out what they can do for you. 

GTO CP5 Servo Drive Specification

Electronic components Rated for industrial and automotive applications
Motoren RA/DEC Brushless micro-step servo system, enclosed in machined aluminum housing
Absolute Encoders R.A. and Declination axes
Servo Motor Control Box GTOCP5 Control Box, removable
Hand held computer (optional) GTO Keypad to control all mount functions. Includes extensive databases and tour features in a simple, intuitive interface. Firmware updates via the internet
Power requirements Nominal 12 to 24 Volt DC supply, minimum of 5 amps continuous
12 Volts: Tracking - 1.5 amps DC,  Slewing - 3.5 amps DC, 4.2 amps (50 watts), both axes slewing
24 Volts: Tracking - 0.8 amps DC,  Slewing - 3.5 amps DC, 3.6 amps (86 watts), both axes slewing
Periodic error (native) 0.25” arc seconds peak-to-peak, 0.05 RMS
Maximum slew speed 5 degrees / second at 12V
7.5 degrees / second a 24V

CP4 Control

Flexible Control with Your Keypad, Computer or even your Mobile Smart Device!

As this chart shows, there are many options available for controlling your mount. For detailed information about the Mach2 GTO please visit the original website of Astro-Physics. If you have any further questions, please send us an email to kontakt (at) or call us.

What's included:

  • Mach2GTO Equatorial Head with Dual Absolute Encoders 
  • GTO Servo Control Box
  • Control Box Adapter
  • 13.675" Stainless Steel Counterweight Shaft, 1.875" (47.6 mm) diameter with Machined Safety Stop Knob
  • 6' Cable with PowerPole Connector and Clip
  • 15' Straight-through Serial Cable
  • 1/4-20 Machined Knob Kit
  • Allenhead wrench set
  • AC-DC Power Supply, universal 85-240V to 24V DC at 10 amps
  • ASCOM driver, available by download
  • APCC Software, Pro version
  • Thumb Drive containing: PDF of Mach2GTO and Keypad instruction manuals
  • Manual: Mach2GTO German Equatorial and GTOCP5
  • Registration Card

Payload Capacity Mach 2

Payload Capacity Astro-Physics Mach2
To enlarge, please click on the graphic.

The payload capacity of an astronomical mount (which includes the telescope and accessories, but not the counterweights) depends on the mechanical dimensions of the telescope setup. The maximum load capacity indicated by the manufacturer refers to the loads at which the specifications given in the technical data can be adhered to, especially the specifications for the stability and precision of the RA drive.

It is logical that the larger the mechanical dimensions of the payload are, the less the telescopic configuration should weigh, because the centre of gravity moves farther away from the intersection of the axis cross as the dimensions (diameter and length) increase.

The right ascension axis is mainly affected by the telescope weight and the mass of the counterweights, while the declination axis is mainly affected by the overall length of the telescope. The longer the length, the more the axis is stressed by torsion and wind load.

The graph shows the recommended instrument load for a Mach 2 depending on the mechanical dimensions. It shows the relationship between weight and tube diameter. The vertical axis shows the weight from 17 to 40kg, while the horizontal axis shows the tube diameter (height) from 4 to 20 centimeters. All telescope combinations in the green range are recommended, those in the yellow range are in the range of limited conditions. Combinations in the red area should be avoided, it is to be assumed that the mount will be permanently damaged during longer operation (mainly the worm wheel drives and the drive motors).

The diagram below shows recommended combinations of overall length and telescopic weight. On the vertical axis are weights between 10 and 40kg, and on the horizontal axis are lengths between 900 and 1800mm.


Applies to all mounts which are controlled through plug connections of hand controllers and / or through plug connections with electronic accessories.

Again and again, we receive mounts for repair work, which have malfunctions due to corroded connections. Therefore, the following note:

The plug-in connections at all contact points in astronomical telescopes are generally exposed to humidity and dirt. For the current transmission on such plug-in connections there is often a higher risk of damage due to humidity or corrosion as is ussually the with plug-in connections in the household.

It is advisable to spray the connectors of all cable connections generously with contact spray and then plug in the respective plug several times. In this way, the contact is cleaned and at the same time corrosion and the accumulation of condensation water are prevented. Please do not spray into the socket! In this way, short circuits can be produced if contact liquid is used too generously and runs through electronic components inside the device.

In any case, if there are undefined malfunctions during the electricity or signal transmission, it is first of all advisable to clean the plug-in connections by means of contact spray.

Related Articles

Additional Information

Technical Data not yet specifiedPlease choose product variant from dropdown above to see technical data of your chosen product

You may also be interested in the following product(s)

Tell us what you think about this item!

Write A Review
    Please, wait...