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Astro-Physics Mach1GTO Computerized German Equatorial Telescope Mount

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Astro-Physics Mach1GTO Computerized German Equatorial Telescope Mount

There is much to admire in the Mach1GTO. It is beautifully machined, intelligently designed, precisely fabricated and assembled, and it has sophisticated electronics and servo drive controls. But the bottom line is performance and results.

Sky & Telescope Magazine published a test report of the Mach1GTO with the GTOCP3 Control Box (prior version) in the December 2007 issue entitled "Staying on Track". Earlier that year, Dennis di Cicco, Sky & Telescope Senior Editor, had tested Televue's TV-NP127is refractor, Apogee's Alta U9000 CCD camera and theMach1GTO together over a number of imaging sessions. Based on his experiences, Dennis wrote three different reviews. The December article focuses on theMach1GTO (PDF is linked with permission).

"The mount just faded into the background as I worked with the scope and camera. Each night I'd turn it on; press a few buttons to slew to a bright star (usually before sunset), confirming that the mount was still synced with the sky; and go about my observing. Night after night the Go To pointing, sidereal tracking, and autoguiding remained virtually flawless. The fact that the mount proved so unobtrusive as I busied myself otherwise is, in my opinion, one of its greatest qualities especially since its setup had been so easy."

If you're in the market for a quality, midsize German equatorial mount that's highly suited to portable and permanent installations, you should definitely consider the Mach1 GTO. I can't imagine anyone being disappointed with its performance. The nameplate says Astro-Physics," and after months of using it, I know it's good."

The Astro-Physics Mach1GTO was the first, compact, light-weight mount that was designed for utmost portability while maintaining extreme rigidity and excellent tracking accuracy. No shortcuts were taken to achieve these goals. From the highly-accurate fine-pitch gearbox to the precision-machine tool bearings, to the innovative worm wheel and clutch design, this mount represents an approach that is a vital part of the overall imaging train.

There is much to admire in the Mach1GTO. It is beautifully machined, intelligently designed, precisely fabricated and assembled, and it has sophisticated electronics and servo drive controls.

Whether your Mach1GTO makes a permanent home in your observatory, explores your favorite observing sites or travels to the ends of the earth with you, it will allow you to optimize your observing sessions to the max. Ideal instruments include: Astro-Physics and similar fast refractors up to 160 mm, 8-11" SCTs, 6-8" Maks or any scopes of a similar size.

Astro-Physics Mach1GTO Highlights...

Portable Enough for Airline Travel

Transport this rigid observing platform to your dream destination. The entire mount will fit into a single rugged case that will roll easily through airports or to your car. If needed, the R.A. and Dec. axes split easily into two pieces to fit into a more compact case.

Operate with 12V battery or Regulated Power Supply

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.

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.
Dennis di Cicco had this to say about the "powerful meridian delay feature" in his 2007 review:

". . . makes it easy to set up photographs that track across the meridian without interruption. It may sound like a small feature on paper, but I found it extremely useful in the field . . ."

Easy Alignment for Non-critical Observing

You can align the Mach1GTO using setup routines in the optional keypad to quickly zero in on the pole for most non-critical observing or to get close before tweaking in for imaging. Our optional Right-Angle Polar Alignment Scope will allow you to quickly zero in on the pole or the polar alignment routine in PEMPro (optional) will guide you through the process. 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 using the GTO Keypad (optional), which is a full-featured handheld computer, PC computers using a wide variety of software with or without our ASCOM driver, Mac computers using a nice choice of software, 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.

AP Mach1GTO 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.

Although the Mach1GTO is very light for its size and load rating, it has been machined out of solid aluminum to withstand the high axial and thrust loads that a medium-sized telescope places on the mount under real-world observing conditions. The mount is solidly built and will withstand gusting winds without excessive shake or vibration. We used high-quality machine tool bearings, rated in excess of 400 lb. static and dynamic load, on the main axis shafts. Both worm wheels turn smoothly with no runout throughout their 360-degree range.

Dennis di Cicco had this to say about the Mach1GTO's performance:
"The mount's tracking and Go To pointing are among the most accurate I've ever tested. At the end of each night, I'd park the scope and turn off the power. Whether an hour, day, or week elapsed until I'd power up the mount again and resume from park, it would have perfect sync with the sky even to the point of hiding stars behind my finderscope's crosshairs when I'd check the alignment by slewing to them in a bright twilight sky . . .
Such Go To pointing precision comes in handy when shooting photographic mosaics, making a sequence of deep exposures of the same field on multiple nights, or hunting difficult targets by eye."

Precision-Adjust Rotating Pier Base / Hi-Res Azimuth Adjuster:

Precision-Adjust Rotating Pier Base / Hi-Res Azimuth Adjuster
The Precision-Adjust Rotating Pier Base / Hi-Res Azimuth Adjuster offers the same smooth and precise rotation as experienced when using the precision-adjust rotating pier adapters with our larger mounts. Regardless of the mount's load, hi-res adjustments can be made in azimuth with no lockdown needed, which could shift your position.

The azimuth adjuster knobs are now at the rear of the R.A. axis, which provides easier access and nearly doubles the precision of their adjustments. An etched line on the adjuster housing corresponds with the ridges of the knobs to provide a measured adjustment of 0.7021 degrees (42 arcminutes) per rotation or 0.05 degrees (3 arcminutes) per ridge.

These features were introduced in June 2011. If you own a mount shipped in prior years, the base can be easily removed and upgraded.

Clutches and Interchangeable Motor / Gear Boxes

Clutches allow manual operation if power is not available.

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. All electronics including the GTOCP4 control box, motors, gearbox or cables can be removed for servicing. The R.A. and Dec. axes can be shipped separately if needed.

Route your cables through the mount for tangle-free operation and peace of mind.
Both axes have 2-inch clearance holes down the center with no shafts protruding into the holes. Wires from CCD cameras and accessories can be inserted from the bottom of the RA axis to emerge from the top of the Dec axis. Channels have been machined to allow the cables to be routed under the mounting plates. There is no restriction of rotation with the wires inserted - one can rotate both axes more than 360 degrees without catching the wires on any parts. The mounts shipped starting in June 2011, have a larger cable channel at the top of the Dec. axis than the earlier mounts.

Use Accessories you May Already Own
If you already own our previous 400 or 600E German Equatorials or other Astro-Physics mounts, you will be pleased to learn that many of the same accessories can be used with the Mach1GTO. These include counterweights, mounting plates, polar alignment scope, piers and tripods.

Fast and Precise Polar Alignment:

The CNC machined Right-Angle Polar Alignment Scope (RAPAS, sold separately) allows you to polar align the Mach1GTO in record time and with a precision that permits you to immediately begin imaging. Its revolutionary right-angle design will immediately win you over. No longer will you be kneeling on the ground, straining your neck to try to polar align. Instead, you will comfortably look down into the scope. The first thing you will notice is that it is only necessary to position Polaris on the circular grid pattern of the reticle. This can be done even in light polluted skies. All that is necessary is to be able to see Polaris, a 2nd magnitude star.

There are several ways to know where to position Polaris on the circular reticle grid. The Astro-Physics ASCOM V2 driver includes the Astro-Physics Polar Alignment Scope Utility that duplicates the grid and provides a continuously updated positioning of Polaris. Similarly, one can use the Astro-Physics PolarAlign App for iPhone/iPad/iPod Touch, or a soon-to-be-released Android App. Those of you who wish to do it the old-fashion way can calculate Polaris' position in local sidereal time.

GTOCP4 Servo Drive System:

Like the previous GTO mounts, the GTOCP4 drive system uses a high-quality Swiss DC servo motor controlled by a microprocessor to an accuracy of 0.05 arc-seconds per step. Tracking is very smooth, noticeably smoother than any stepper motor drive or inexpensive servo motor. The system can be accurately controlled over a speed range of 4800:1, which allows 0.25x sidereal for manual guiding to 1200x sidereal for 5 degrees per second slewing. The circuit draws only 0.4 amps when tracking the stars, 2 amps with both motors slewing and requires only 12 volts to operate. The servo drive will satisfy the requirements of the sophisticated, advanced astrophotographer, yet is easy for the casual, visual observer to use.

Gear Accuracy and PE Performance:

The heart of this mount is a precision gearbox using custom high-quality fine-pitch gears, coupled to a highly accurate worm and worm wheel. These parts are manufactured and assembled at the Astro-Physics facility and individually tested to meet or exceed a periodic error specification of 7 arc seconds (+/- 3.5 arc sec.) before introducing any periodic error correction. The PE is smoothly variant with extremely low ripple or moment to moment error. In contrast, mounts that use integral gearboxes have very small spur gears with tiny teeth and too few of them. This generally causes ripples in the tracking rate which are difficult to guide out.

Each mount is rigorously tested on a specialized periodic error tester. Only mounts that provide an accuracy of 7 arc seconds or better will pass this inspection. If the mount exhibits greater error, the sub-standard part is identified, replaced and the mount is re-tested.

GTOCP4 Control Box:

The GTOCP4 Control Box contains all of the circuitry to drive the two servo motors and the logic required to navigate the sky. It can be easily removed from the mount if required. TheMach1GTO uses the same GTOCP4 Control Box (with the exception of the completely black-anodized exterior), as its big brothers - the 1100GTO and 1600 GTO mounts. In fact, the control boxes for all three mounts are interchangeable with one another in an emergency.

GTO Keypad:

The Keypad is a self-contained computer that allows you to control all essential telescope functions and includes an extensive database of objects. AP has designed the interface and firmware to be as intuitive and easy to use as possible while filling it with terrific features to make your observing session productive and pleasurable.

Items that You will Need for Your Mount

  • Mounting Plates: FP1500, 900RP, DOVE15, DOVELM2, DOVELM162, and DOVE08 (requires Q4047)
  • Pier or Tripod: Astro-Physics Portable Pier - 6" diameter, heights 24", 32", 42", 48", 54", 60"; or Berlebach Planet Tripod. If you choose the Berlebach tripod, be sure to include the Control Box Extension Adapter.
  • 12V Battery or Power Supply that convert 110VAC to suitable DC
  • Counterweights: Stainless Steel Counterweights - 6, 9 lb.


DEC Worm150mm Diameter 225 Teath
Drive TypeSwiss DC servo motor
Encoder Resolutionseconds per step
Encoder Type2000 tic quadrature
Head DesignGerman Equatorial
Instrument Capacity65 lbs
Latitude Range0 to 70 Degrees
ManufacturerAstro Physics
Mount Head Weight28lbs
Pointing Accuracy+/— 3 Arcseconds
Pointing Accuracy<1 Arcsecond
PortsUSB 2.0
RA Worm150mm Diameter 225 Teath
Slew Speed5 degrees / second