Mach1GTO German Equatorial Mount
with GTOCP3 Control Box

Observatory Performance in a Small Package!

Includes GTO Keypad and PulseGuide software CD





Read the Test Report from the December, 2007 Sky & Telescope Magazine!
"Staying on Track" by Dennis di Cicco
(PDF - linked with permission)

New in 2007

After we completed our lengthy testing on the prototype and units from the first production run, there wasn't much that we needed to upgrade. The Mach1GTO is proving itself to be a solid, reliable performer both in the field and permanently mounted in an observatory. These are the only significant changes in the next production run:

Why a Mach1GTO?

Design Goals:

This is the first, compact, light-weight mounting 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 a new approach to this vital part of the overall imaging train.

The advent of modern CCD cameras and telescopes with high resolution optics has placed greater demands on the ability of mountings to do their part to achieve precision tracking and guiding. At the same time, the mounting should be easy to use with adjustments and setups that are straight forward and accurate. We have done everything possible to eliminate the frustrations and limitations inherent in a lesser mounting and so put the fun back into the hobby of amateur astronomy.

Principal features of the Mach1GTO Equatorial Mount:


Portable Enough for Airline Travel
Transport this rigid observing platform to your dream destination. The mount will fit into a rugged carry-on case and will roll easily through airports or to your car.

Sophisticated Enough for Remote Operation
The Mach1GTO was designed from the ground up to take full advantage of the latest electronics. The integral internal cable channel allows multiple electronic devices to be used without the usual tangled cable nightmare. The Mach1GTO uses the same servo control box, the GTOCP3, as its big brothers - the 900GTO and 1200GTO mounts. This cutting edge electronic marvel coupled with software like Ray Gralak's wonderful PulseGuide (included) and your PC make remote operation a pleasure.

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.

Clutches and interchangeable motor / gear boxes
Clutches allow manual operation if power is not available. If, heaven forbid, your RA motor fails, simply swap the Declination motor / gear box and resume tracking in RA. This will be a much appreciated backup procedure when you are far from home on an extended vacation.

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.

Easy Alignment for Non-critical Observing
You can align the Mach1GTO with a polar alignment scope (not included - preferably either PASILL4 or the prior PASILL3 model since they can rotate in the axis) to quickly zero in on the pole for most non-critical observing or to get close before tweaking in for CCD. You can even align it 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.

External Computer not Needed
The Keypad is a handheld computer with all of the features, functions and databases you need to tour the universe night after night. The unique firmware allows you to precisely polar align your mount in the field, even in broad daylight! The vacuum-fluorescent display with a temperature range of -40 degrees F (and C, they are the same in this instance), allows hardy observers to use this mount on cold winter nights. You can't do that with a PC or PDA! As new firmware versions are released in the future, you can upgrade your keypad directly from the download section of our web site - free of charge!

Control with personal computer, if desired.
All functions of the servo drive can be commanded from a laptop or desktop computer using popular planetarium software. Depending on the features of the program, you can position your telescope, center your image and control tracking rate, remote focusing, reticle brightness and park at the end of your observing session. The Mach1GTO's unique 2 inch internal cable path allows a multitude of electronics to be routed THROUGH the mount where they won't tangle, snag, or otherwise cause problems. This innovative feature makes computer controlled imaging and guiding a pleasure. Examples of currently available software:

Write your own computer program.
The Astro-Physics GTO protocol for the GTOCP3 Control Box is freely available to those who would like to write their own computer program for controlling the mount.

Precise Mechanical Fabrication

Highly accurate mechanics
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.

Worm gear accuracy
Critical worm gear accuracy is maintained by special machining techniques developed at Astro-Physics after extensive studies and actual field operation. Our worm accuracies are second to none and are guaranteed to be 7 arc seconds (+/- 3.5 arc sec.) or less peak-to-peak for the Mach1GTO. The periodic error of each mount is verified during our extensive testing procedures. With good alignment and PEM training with the Keypad or PEMPro software, it is quite practical now to achieve unguided CCD images with today's hi-resolution cameras coupled to a 4" to 10" telescope.

Mechanical Features

Prototype Mach1GTO shown with SBIG STL-11000XM camera and its power supply with a variety of cables

Specifications of Equatorial Head

Worm Wheels - both axes

5.9" (150mm), 225 tooth aluminum

Worm gears

Brass, 0.709" (18mm) diameter

R.A. and Dec. thrust surfaces

4.1" (104mm) diameter


3.1" (78mm) diameter - 2 per axis

Periodic Error Maximum

7 arc seconds peak to peak, (+/- 3.5 arc sec.) or less in one worm cycle (6.4 minutes)

Axis Shaft Diameters

2.36" (60mm)

Latitude range

0 to 70 degrees

Azimuth adjustment

25 degrees (+/- 12.5 deg. from center)

Motor Power Consumption

400 mA - tracking
2 Amps - both motors slewing

Power Requirements

12V DC, 5 Amp. (Acceptable Range: 11.5 to 16V)


Approximately 45 lbs. (20kg) scope and accessories (not including counterweights), depending on length. Will accommodate Astro-Physics and similar fast refractors up to our 160mm f7.5 StarFire EDF, 8" - 11" SCT's and 6" - 8" Maks.
These are only guidelines. Some telescopes are long for their weight or very heavy for their size and will require a larger mount. Remember also that imaging requirements are more rigid than visual observation.

Weight of equatorial head

28.5 lbs (13.0kg); Declination axis is 11.5 lbs. (5.2kg); Right Ascension axis is 16 lbs.(7.3kg); Pier adapter is 1 lb. (0.5kg)

Counterweight Shaft 1.125" diameter X 14.5" long, 4.1 lbs. (29mm X 368mm, 1.9kg) This shaft uses the same 6 lb. and 9 lb. counterweights that were used with the 400, 600 and 800 series mounts.

NEW Optional Counterweight Shaft (M1053-A) (must be purchased separately)

1.875" diameter X 10.70 " long, 7.7 lbs. (48mm X 273mm, 3.5kg) This shaft is the same diameter as the shaft for the 900 and 1200 mounts and uses the same counterweights as well as a 5 lb. counterweight produced especially for the Mach1GTO. Longer sizes and an extension are available. Requires Safety Stop (M12676).

Servo Motor Drive

The 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 guiding to 1200x sidereal for 5 degree 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. Please refer to GTOCP3 Control Box and Keypad for Servo Drive for additional information.

Pier / Tripod Mounting Options

The Mach1GTO can be mounted directly into the top of an Astro-Physics 6" Portable Pier or on our 6" Eagle Adjustable Folding Pier (EAGLE6). It can also be mounted on the Adjustable Wood Tripod (AWT000) or the Lightweight Adjustable Aluminum Tripod (SDS400) The ADATRI adapter allows the Mach1GTO to be mounted on your own custom pier or tripod and can be purchased separately. To determine the appropriate pier height for your system, please try this Excel spreadsheet Latitude Dimension Calculator.

PulseGuide™ Software

PulseGuide is a stand-alone Windows (98, ME, 2000, NT4, XP only) utility that provides complete remote control of the Astro-Physics Mach1GTO, 400GTO, 600EGTO, 900GTO, and 1200GTO mounts. It derives its name from its most distinctive feature, pulse guiding, which can improve unguided tracking. Specifically, it can help correct tracking errors caused by polar misalignment and atmospheric refraction. You can also train PulseGuide to track objects moving relative to the stars, such as asteroids, comets, and the moon. In addition to pulse guiding, PulseGuide also has many useful utility features. With just a few exceptions, it supports the entire serial Astro-Physics command protocol allowing full control of your mount through your PC. This program is indispensable for remote control of your mount. More ....

PulseGuide was written by Ray Gralak of Sirius-Imaging. Please refer to his web site for further developments and enhancements. The software will be provided on a CD-ROM with your Mach1GTO mount. Previous owners of any Astro-Physics mounts can download the software free-of-charge, courtesy of Ray. Many, many thanks to Ray for this powerful program.

PEMPro Software

PEMPro (Periodic Error Management Professional) is a Windows software application that makes it easy to characterize and reduce periodic error. It may be purchased separately as an option. While the periodic error of your Mach1GTO will be 7 arc seconds (+/- 3.5 arc sec.) or less, you can reduce it even further to maximize performance without auto-guiding. More ...

Price and Delivery Information

The first production run shipped during the last four months of 2006 and has been hailed as a huge success. We were excited and honored to have the Mach1GTO chosen as one of Sky & Telescope's Hot Products for 2007! As I write this on February 17, 2007, we have almost finished all of the machined parts for our next and larger production run. We will be contacting people who are on the notification list beginning within the next few days, though the notification period is likely to extend for a few months. Many people originally signed up on the 400GTO/600EGTO notification lists, which we have merged together into the Mach1GTO list. If you are not already on one of these lists, you can sign up on our online notification form. A confirmation e-mail will be sent to you for your records.

Mach1GTO $5,950.00

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This page was last modified: September 20, 2013

Astro-Physics, Inc.
11250 Forest Hills Road, Machesney Park, IL  61115, U.S.A.
Phone: 815-282-1513   Fax: 815-282-9847