1600GTO German Equatorial Mount (1600GTO)
with GTOCP3 Control Box
Includes GTO Keypad and CDs with
PulseGuide and PEMPro (full version) software
Why a 1600GTO?
Thirty plus years of mount design and building expertise
plus actually using the equipment 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
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:
Improved Features Compared to the 1200GTO, its Predecessor
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
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 10.3" 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
- 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 "captain's wheel"
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. This also allows you to transport the RA assembly in a more compact, zero degree latitude configuration.
- 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 (optional)
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.
Image past the meridian.
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 13.8-volt, 5-amp Power Supply (PS13V5A). For a heavy payload in cold conditions, we offer a 15-volt, 12-amp power supply (PS15V12AC).
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.
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:
The 1200GTO’s ability to continue tracking when past the meridian is an absolute winner for me. It avoids meridian flips (=imaging time) and reduces the need for expensive rotators. Jan Rek.
Easy alignment for non-critical
. . . I love the ability to place the OTA on the "wrong side" of the mount when starting an imaging session ("premature meridian flip") and which I have used extensively. This feature is pure INGENUITY! Anthony Ayiomamitis.
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. GTO control options are discussed
in detail at this link.
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 1600GTO 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.
||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 and 90 degrees for Alt-Az
| Azimuth adjustment
|| Approximately 13 degrees (+/- 6.5 degrees from center)
|| 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: 114.0 lb. (51.8 kg)
R.A. axis/polar fork: 58.5 lb. (26.6 kg)
Dec. axis: 38.5 lb. (17.5 kg)
Dec. top plate 3.0 lb. (1.4 kg)
Counterweight shaft: 14 lb. (6.4 kg)
||Approximately 220 lb. (100
kg) scope and accessories (not including counterweights), depending on
length. Recommended for refractors up to 250 mm, 18-20" Cassegrains, Ritchey-Chretiens
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.
The drive system uses a high-quality, heavy-duty 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 degree per second slewing. The circuit draws approximately 0.5 amps
when tracking the stars, 2.5 amps with both motors slewing and requires only
12 volts to operate. The servo drive will satisfy the requirements of the sophisticated,
advanced astroimager, yet is easy for the casual, visual observer to
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 our facility and individually
tested to meet or exceed our periodic error specification of 5 arc seconds (+/-
2.5 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 our specialized periodic error tester. Only
mounts that provide an accuracy of 5 arc seconds or better will pass this inspection.
If the mount exhibits greater error, the substandard part is identified, replaced
and the mount is retested.
Pre-loaded PEMPro Curve
As mentioned above, the spec of 5 arc seconds (+/- 2.5
arc sec.) is the maximum native mechanical error inherent in the mount's RA axis
WITHOUT any software correction. In order optimize performance even further,
we use a special version of Ray Gralak's PEMPro (described below) developed specifically
for our test equipment. We generate a unique PE curve for each mount that we
program into each GTOCP3 Control Box. Simply use the Keypad or your Astro-Physics
software (ASCOM V2 driver, PulseGuide or APCC) to turn the PE Correction "on" and
you will see results significantly better than our published 5 arc second spec
without additional PEMPro runs! However, you may use PEMPro to further refine
your PE, if you chose to do so.
GTOCP3 Control Box
The GTOCP3 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.
The 1600GTO uses the same GTOCP3 Control Box as the 1100GTO and Mach1GTO (the
control box is black-anodized for the latter mount).
In fact, the control boxes for all three mounts are interchangeable with one
another in an emergency. Extensive information regarding the GTOCP3 can be found here.
The Keypad is a self-contained computer that allows you to control all essential telescope functions and includes an extensive database of objects. We have 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. Click here for
detailed information regarding features and functions of the Keypad.
GTO Servo Drive System Specifications
||Rated for industrial and automotive applications
||High-torque, zero-cogging Swiss DC servo motors, enclosed in machined aluminum housing
||2000 tic quadrature yielding an effective resolution of 0.050 arcseconds per tic
|Motor reduction gear train
||57.6:1 gear reduction through a custom built set of large diameter, fine-toothed, precision, spur gears for vastly superior performance
|Servo Motor Control Box
||GTOCP3 Control Box, removeable
||GTO Keypad to control all mount functions. Includes extensive databases and tour features in a simple, intuitive interface. Firmware updates via the internet
||~ 0.3 to 0.6 amps at 13.8 volts - tracking
~ 1.3 to 2.5 amps at 13.8 volts - both motors slewing at 1200x
||Nominal 12 volt DC supply at minimum of 5 amps continuous
5 arc seconds peak-to-peak (+/- 2.5 arc seconds) or less in one worm cycle (6.4 minutes); native, prior to any error correction
|Maximum slew speed
||5 degrees / second
Absolute Encoders (optional)
The 1600GTO mount has been designed
and engineered to accomodate the use of extremely precise Absolute
Encoders. Absolute Encoders allow the mount to know its exact location
regardless of accidental software errors and will allow it's recovery.
This is particularly important in remote setups. Furthermore, they virtually
eliminate periodic error, reducing it below 0.2 arcseconds in our tests.
The encoders can be user installed on both axes, or on just the RA axis
based upon the user's need. This frees the user from having to make the
decision to include the encoders at the time of the mount's purchase; rather,
they can be added later as need arises. Check out the 10 minute (600 seconds) unguided exposure by clicking on the thumbnail to the left.
Flexible Control with Your Keypad, Computer or even your
Mobile Smart Device!
Software, Version 2
||As this chart shows, there are many options
available for controlling your mount. Take a few minutes to link
to descriptions of the varied software and devices that are available.
You will be able to further link to a full size view of this
chart and discover more about each method.
PEMPro (Periodic Error Management Professional), Version 2, by Sirius Imaging is a very powerful Windows software application that allows you to correct your mount's periodic error, polar alignment and backlash using your CCD Camera or Webcam to dramatically improve tracking and guiding.
As mentioned previously, our extensive testing procedures include several PEMPro runs so that your new mount will perform with optimum PE correction out of the box. Simply use the Keypad or the PulseGuide software to turn PE Correction "on." Although you will not need to use PEMPro when you receive your mount, you may wish to do a PEMPro run at a later date after the worm gear has run in. Depending on usage, re-measuring error and re-loading periodic error correction from one to four times a year is a good practice, especially if you do some unguided images from time to time.
Pier Mounting Options
The 1600GTO mount integrates a precision rotating pier adapter and azimuth adjuster as part of its base. The mount's base will directly attach to the Astro-Physics pier, or it can be attached to any flat surface using the Flat Surface Adapter for 1600GTO and
all 1200 Mounts (1612FSA). When choosing the Advanced Telescope System's (ATS) Pier, you will need to order our Flat Surface Adapter with Flat Pier Plate 1612FSA-FP that will fit into the top of their pier. The 1600GTO's large adjustable 0 to 78 degree latitude range (which spans from Antarctica to the arctic circle) makes the use of a wedge unnecesary.
To determine the appropriate pier height for your system and to calculate many of the dimensions that vary with your latitude setting, please try this Excel spreadsheet Latitude Dimension Calculator.
All Astro-Physics mounts are supported by a dedicated staff who will assist with any issues that may arise. You can talk to a real person in a timely manner. Astro-Physics staff also participate in the ap-ug and ap-gto user groups in the Yahoogroups forum. The user groups are comprised of scope and GTO owners who are willing to share their wealth of experience using their mounts as well as imaging strategies and other concerns of advanced amateurs.
Price and Delivery Information
1600GTO - What's Included?
- 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
- R.A. / Dec. Y-cable
- 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
Items that You will Need for Your Mount
- Counterweight: Stainless
Steel Counterweights - 5, 10, 18, 24 lb.
- Saddle Plate:
- D-Style (3") Dovetail Plate: Check out our wide
Dovetail Plates, 13" and
16" Side-by-Side Plates (SBD13SS and SBD16SS) and Vixen
Dovetail Converter (SBD2V)
- P-Style (7.65") Dovetail Plate: 23" PlaneWave
Style Dovetail Plate (SBPW23)
- Pier: Astro-Physics Portable Pier - 10" diameter, heights 24",32",42",48",54",62", Advanced Telescope Systems (ATS) Portable Pier or build your own permanent pier
- Regulated Power Supply: 13.8-volt, 5-amp (PS138V5A) or 15-volt, 12-amp (PS15V12AC) Regulated Power Supply with Cigarette Adapter
- Portable Rechargeable 12-volt Battery Pack: Several sizes
and types are available from a variety of vendors. Be sure that your battery
pack can supply adequate power for an entire observing session! We recommend
having separate batteries - one for the mount and another for all other accessories:
camera, dew removers, etc. We do not offer any battery packs at this time.
Additional Accessories to Consider
Back to Products
Back to top
Copyright © 2012, Astro-Physics,
Inc. - All Rights Reserved
This page was last modified:
September 20, 2013
11250 Forest Hills Road, Machesney Park, IL 61115, U.S.A.
Phone: 815-282-1513 Fax: 815-282-9847