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Astro-Physics 1600GTO German Equatorial Mount

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Product Description

Thirty plus years of mount building expertise has been employed to engineer and build our new 1600GTO mount into the most robust, high-precision mount in its class. We have enhanced its design and utility by incorporating additional optional features like absolute encoders, sophisticated control systems and a new precision polar scope to exceed the needs of even the most demanding astro-imager or visual enthusiast.  Although we believe that the 1200GTO will continue to provide years of excellent performance, we felt that the time had come to improve the ease of use and add new features to take it into the future. We listened to your suggestions and added a few of our own. Some of them make the mount easier to set up for portable use, others set the standard for remote imaging. The modular design allows you to easily upgrade your mount if you build an observatory for near (backyard) or remote (halfway across the world) imaging.

We also felt that we needed to increase the size differences between the Mach1GTO, 900GTO and the 1200GTO, which were too close together and overlapping. Since the "new 1200" has greater capacity than the original 1200, we felt that it should have another name and selected 1600GTO "Sweet 16". Nevertheless, it maintains the heart of the 1200. Here are some changes that you may find useful:

  • Dec. axis gear increased to 10" for higher payloads and more stability
  • Azimuth adjusters have been repositioned to the rear of mount which allows you to make minor corrections quite easily without reaching or moving around the mount. Since the knobs are now in front of you as you look through the polar scope, the graduations can be more easily seen as you dial in your position.
  • Built-in precision-rotating pier adapter is now included and not purchased as a separate item.
  • Major altitude adjustments are extremely easy to make. Simply shift the position of the bar into a new slot without having to line up obscure holes referenced in the manual. The large hand knob is also very easy to grasp and turn. If you travel to a star party at a different latitude, you can make changes to your setup very quickly.
  • Altitude range has expanded on both ends and now extends from 0-78 degrees, which makes it suitable for most anyone except the extreme polar locations. The Hi-Low Wedge is no longer necessasry.
  • New Right-Angle Polar Alignment Scope can be used without the need for an additional adapter
  • Unobstructed Dec. opening for Polar Alignment Scope allows greater field of view for both the Astro-Physics Right-Angle or the Losmandy Style Polar Alignment Scopes.
  • Internal routing of motor cables to remove the possibility of snagging.
  • Easily route additional cables through the large openings in the R.A. and Dec. axes. The top of the Dec. axis separates so that you can add cables with large connectors.
  • Right-angle connectors are used in most locations to reduce strain on the cables.
  • Larger motors for increased torque in cold temparatures. These are the same motors as used in the current 3600GTO mount. Note: The 1200GTO mounts produced in 2011 also have these motors.
  • Automatic worm gear mesh is quick and easy. Produces the best settings on the worm teeth and repeatable settings.
  • Improved clutch system with NO clutch plugs that can potentially deform over time if they are overtightened. This issue has been eliminated.
  • Clutch can be set to any amount of engagement up to complete locking of the axes so nothing can slip.
  • Control box mounted on the side rather than the top to reduce the possibility of moisture getting into the electronics in damp environments.
  • Greater capacity to provide a rigid platform for fairly large instruments or side-by-side setups.
  • Absolute Encoder option to provide error-free tracking, software readable absolute position, customizable home and limit functions for robitic imaging. This option can be installed whenever you are ready to take advantage of its capabilities.

The 1600GTO mount is built from the ground up to be a precision imaging platform while still remaining totally user-friendly. Consider these advantages and features:


Extremely solid, rugged, high payload mount, yet the equatorial head comes apart into two components for hassle-free field setup.

Operate with 12V battery.

You can take it to the darkest skies and power it with a commonly available 12V battery. In the observatory, we suggest a minimum 5 amp filtered, regulated power supply like our 13.8V, 5-amp Power Supply (PS13V5A). For a heavy payload in cold conditions, we offer a 15V, 10-amp power supply (PS15V10AC).


Allow manual operation if power is not available. One of the truly unique features of the 1600GTO is the ability to use the clutches to help you balance your setup, then you can bolt the R.A. and Dec. axes in place so that they do not move for clutchless operation.

Image past the meridian.
The mount will track and guide well past the meridian in either direction if the object is located such that the telescope will clear the pier. This allows the user to set up the mount for a long series of exposures without stopping in the middle to flip sides. One can start the telescope under the mount while pointing at an object in the eastern part of the sky and track it all the way deep into the western sky. This is very useful for long exposure H-alpha or in cases where a large number of individual exposures are needed for stacking. This feature of our GTO mounts has been a real customer favorite.

Easy alignment for non-critical viewing.
You can align the 1600GTO using setup routines in the keypad, or with a polar alignment scope to quickly zero in on the pole for most non-critical observing or to get close before tweaking in for imaging (polar scope not included). You can even align the mount during the day with our clever Daytime Polar Alignment Routine (outlined in the Keypad Manual) for solar observing, viewing the planets at twilight, or just getting a jump start on a long night.

Multiple Options for Controlling your Mount in the Field or Your Observatory
You have your choice of the GTO Keypad (included), which is a full-featured handheld computer, PC computers using a wide variety of software with or without our ASCOM driver, Mac computers or even your mobile smart device (like your iPhone or iPad). The Astro-Physics command language is available to those who need to write their own software.

Mechanical Features

Precise Mechanical Fabrication
Using modern CNC machining techniques, we make all components to a high precision level, which results in a final package that is solid and accurate in all respects. The critical angles are accurately machined so that the mount is orthogonal to a very high degree. This results in pointing accuracies well below 1 arc minute for a properly aligned mount. Massive thrust bearings and preloaded shaft bearings provide excellent stability under all imaging situations.

Easy to Adjust and Maintain
The design of the Mach1GTO is straightforward with modular construction and no complicated internal wiring. We provide information in the Technical Support section of our website pertaining to typical adjustment issues.

Components are modular.
All electronics including the GTOCP3 control box, motors, gearbox or cables can be removed for servicing. The RA and Dec axes can be shipped separately, if needed.

Mechanical Specifications

Construction 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. 10.3" (262 mm), 225 tooth aluminum
Worm gear - R.A. & Dec. 1.22" (31 mm) diameter brass
Axis shaft - R.A. & Dec. 3.74" (95 mm) diameter
Shaft axis bearings - R.A. & Dec. 5.71" (145 mm) diameter
Latitude range 0 to 78 degrees
Azimuth adjustment Approximately 13 degrees (+/- 6.5 degrees from center)
Counterweight shaft 1.875" (47.6 mm) diameter x 19.5" (495 mm) long [18.5" (470 mm) useable length], incl. large machined safety stop knob. Optional 9" (229 mm) shaft extension available.
Weight of mount

Total: 115.5 lb. (52.5 kg)
R.A. axis/polar fork: 58.5 lb. (26.6 kg)
Dec. axis: 40.5 lb. (19.5 kg)
Dec. top plate 2.5 lb. (1.1 kg)
Counterweight shaft: 14 lb. (6.4 kg)

Capacity Approximately 200 lb. (90.9 kg) scope and accessories (not including counterweights), depending on length. Recommended for refractors up to our 250 mm, 18-20" Cassegrains, Ritchey-Chretiens and CDKs.
These are only guidelines. Some telescopes are very long for their weight or heavy for their size and will require a larger mount. Remember also that imaging requirements are more rigid than visual observation.
Instrument mounting interface Refer to list of suitable mounting plates below
Pier adapter base diameter 9.775" (248.3 mm) Base. The base is an integral part of the mount and azimuth adjuster.
  • Polar Fork/ Right Ascension Axis (R.A.) Assembly
  • Declination Axis (Dec.) Assembly
  • GTO Servo Control Box (GTOCP3)
  • GTO Keypad with 15' Coiled Cable and Keypad Protector (KEYVFK)
  • 19.5" Stainless Counterweight Shaft, 1.875" diameter (M12601-D) and Safety Stop (M12676)
  • R.A. and Dec. Cables
  • 8' Power Cable (CABLPF)
  • 15' Straight-through Serial Cable (CABSER15)
  • Allenhead wrench set
  • Astro-Physics Keystrap and Velcro Cable Ties
  • CD containing: PEMPro v2 Software and PulseGuide Software, both written by Ray Gralak of Sirius Imaging. Also, PDF of 1600GTO and GTO Keypad instruction manuals
  • Manual: 1600GTO German Equatorial
  • Manual: GTO Keypad
  • Registration Card

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