Astro-Physics 1100GTO German Equatorial Mount

ASTRO-PHYSICS
1100GTO German Equatorial Mount
with GTOCP3 Control Box - no longer available
Includes CD with PulseGuide and PEMPro (full version) software

Three models:
1100GTO German Equatorial Mount (1100GTO)
1100GTO German Equatorial Mount with Absolute Encoders (1100GTO-AE)
1100GTO German Equatorial Mount with Extended Temperature Range Encoders (1100GTO-AEL)

1100GTO

1100GTO-AE or -AEL

The 1100GTO German Equatorial Mount with the GTOCP3 Control Box is no longer available to purchase. Please refer to our website for our most recent model in this size category.

The information below is provided for present owners and those who are curious about its history.

Why an 1100GTO?

If the 1600GTO German Equatorial has all the features you desire, but is a bit larger than you need, the 1100GTO was developed just for you. This medium-sized mount travels eagerly to star parties where your 12V battery will keep it running all night or is content to stay at home in your observatory, ready to image while you sleep.

We offer three versions of this mount: 1100GTO, 1100GTO-AE and 1100GTO-AEL. The latter two versions include the Standard Temperature Absolute Encoders or the Extended Temperature Absolute Encoders, respectively. If you order the 1100GTO without the absolute encoders, you will be able to purchase them at a later date to install yourself.

This webpage discusses the features that are common to all three mount versions, except where indicated.

The 1100GTO was introduced at the Northeast Astronomy Forum (NEAF) in Suffern, NY in April 2013. In the video below, George Whitney, from the Astro-Physics Technical Support staff, explains key features of the 1100GTO in an interview conducted by Dennis DiCicco, Sky & Telescope editor. We also invite you to view the entire video for demonstrations of these additional exciting products: 1600GTO German Equatorial mounts with discussion of the Absolute Encoder System used in both the 1100GTO and 1600GTO mounts, Right-Angle Polar Alignment Scope, the 10 x 60 Vario Finder with Quick Release Guider Bracket and the Astro-Physics Command Center (APCC) software.

Improved Features Compared to the 900GTO, its Predecessor

Since the introduction of the 900 German Equatorial Mount in the mid 1990s, it has evolved several times to meet the increasingly greater technological requirements of our customers. The new 1100GTO is the next step in that evolutionary process offering increased capacity, ease of setup and use and enhancements to make your imaging sessions more productive and enjoyable. The modular design allows you to easily upgrade your mount with limit switches or absolute encoders sometime in the future.

Here are some changes that you may find useful:

Dec. axis gear increased to 7.2" (183mm) 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 quick and easy to make by simply shifting the position of the altitude adjustment bar into a new slot. The large "captain's wheel" knob, convenient to grasp and turn, performs the fine adjustments. If you travel to a star party at a different latitude, the changes to your setup are quickly made and allow you to transport the RA assembly in a more compact, zero degree latitude configuration.

Altitude range now extends from 0-78 degrees in its normal configuration. The Hi-Low Wedge is no longer necessary.

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 where applicable to reduce strain on the cables.

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 vertically rather than on the top to reduce the possibility of moisture getting into the electronics in damp environments.

Precision bubble level built into mount base.

Stainless steel lanyard post on either side of base to hang your keypad.

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 robotic imaging. This option can be installed when you purchase your mount (order either the 1100GTO-AE or 1100GTO-AEL version) or you can purchase the option as an upgrade kit when you are ready to take advantage of its capabilities.

Limit/Homing Switch option to provide home and limit functions using a mechanical switch (does not use the absolute encoders). This option will be available in the future.

Versatility

Portable.
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 (PS138V5A). For a heavy payload in cold conditions, we offer a 15-volt, 12-amp power supply (PS15V12AC).

Clutches.
Allow manual operation if power is not available. Use the clutches to easily balance your setup, then lock the R.A. and Dec. axes so that they cannot move when the motors are engaged.

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:

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.

. . . 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.

Easy alignment for critical viewing.
You can align the 1100GTO using setup routines in the optional keypad for most non-critical observing. Our optional Right-Angle Polar Alignment Scope (RAPAS) will allow you to quickly zero in on the pole or the polar alignment routine in PEMPro (included) 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 in Your Observatory
You have your choice of 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 or even your mobile smart device (like your iPhone or iPad). Follow this link to discussions of GTO control options.

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 1100GTO is straightforward with modular construction. 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.	7.2" (183 mm), 225 tooth aluminum
Worm gear - R.A. & Dec.	0.71" (18 mm) diameter brass
Axis shaft - R.A. & Dec.	3.15" (80 mm) diameter
Shaft axis bearings - R.A. & Dec.	3.94" (100 mm) diameter
Latitude range	0 to 78 degrees
Azimuth adjustment	Approximately 18 degrees (+/- 9 degrees from center)
Counterweight shaft	1.875" (47.6 mm) diameter x 14" (356 mm) long [12.875" (327 mm) usable length], incl. large machined safety stop knob. Optional 9" (229 mm) shaft extension available.
Weight of mount	Total: 54.0 lb. (24.5 kg) R.A. axis/polar fork: 26.0 lb. (11.8 kg) Dec. axis: 16.0 lb. (7.3 kg) Dec. top plate 1.5 lb. (0.7 kg) Counterweight shaft: 10.5 lb. (4.8 kg)
Capacity	Approximately 110 lb. (50 kg) scope and accessories (not including counterweights), depending on length. Recommended for refractors up to 200 mm, 14-16" 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. Maximum capacity may require the use of the 9" extension (M12675)
Pier adapter base diameter	7.730" (196.3 mm) Base. The base is an integral part of the mount and azimuth adjuster.

GTOCP3 Servo Drive System

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 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 astro-imager, 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 our facility and individually tested to meet or exceed our 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 our 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 substandard part is identified, replaced and the mount is retested.

Pre-loaded PEMPro Curve
As mentioned above, the spec of 7 arc seconds (+/- 3.5 arc sec.) is the maximum native mechanical error inherent in the mount's RA axis WITHOUT any software correction. In order to optimize performance even further, we use a special version of Ray Gralak's PEMPro 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 7 arc second spec without additional PEMPro runs! However, you may use PEMPro to further refine your PE, if you chose to do so.

1100GTO-AE or 1100GTO-AEL: If you purchase either of these versions with absolute encoders, the final in-house PEMPro run will utilize the corrections of the absolute encoders and the values will be stored in the GTOCP3 Control Box.

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 1100GTO uses the same GTOCP3 Control Box as the 1600GTO 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.

GTO Keypad (optional purchase)
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.

Prior to mid-October 2015, the Keypad was included as part of the mount. However, some of our customers own multiple AP mounts, but only use one at a time. For them, one keypad is sufficient. Others only control their AP mounts with their computer and do not use their Keypad. So, we decided to offer the Keypad as an option. As a result, we were able to reduce the price of the mount accordingly.

Many people do not want to bother with a computer in the field and like the handiness of the Keypad and its ability to operate in very cold temperatures. They will choose to purchase the Keypad.

Optimized for Astronomy
Astro-Physics mounts and the Astro-Physics GTO Servo Control System are designed from the outset as tools for celestial observing and imaging. These mounts do not have any military or defense applications. Applications like missile, airplane, or very low earth orbit satellite tracking require faster tracking rates and more rapid changes to those tracking rates than our mounts allow. Note that the ISS is generally within the mount’s tracking rate capabilities for casual observation.

GTO Servo Drive System Specifications

Electronic components	Rated for industrial and automotive applications
Motors	Zero-cogging Swiss DC servo motors, enclosed in machined aluminum housing
Motor encoder	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, 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 consumption	~ 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
Power requirements	Nominal 12 volt DC supply at minimum of 5 amps continuous
Periodic error	7 arc seconds peak-to-peak (+/- 3.5 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 - 1100GTO-AE and 1100GTO-AEL

10 minute unguided exposure

The 1100GTO mount has been designed and engineered to accomodate the use of extremely precise Absolute Encoders. These are the exact same encoders as are used on the 1600GTO.

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. If you order the 1100GTO-AE or 1100GTO-AEL, the R.A. and Dec. encoders will be installed and fully tested with the mount prior to shipment.

However, if you purchase the 1100GTO without encoders, you may purchase the Absolute Encoder Kit at some point in the future and install them yourself. This do-it-yourself upgrade option will not be available until 2014.

Check out the 10 minute (600 seconds) unguided exposure by clicking on the thumbnail to the left. Note that this image was taken with the 1600GTO, but as mentioned earlier, the same encoders are used on the 1100GTO, so the performance is representative.

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. Take a few minutes to link to descriptions of the varied software and devices that are available.

PEMPro Software, Version 2

PEMPro (Periodic Error Management Professional), Version 2, by Sirius Imaging is included with this mount. It 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. PEMPro also includes a powerful polar alignment routine.

Dimensions

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.

1100GTO: 1100GTO German Equatorial Mount
What’s Included:

Polar Fork / Right Ascension Axis (R.A.) Assembly
Declination Axis (Dec.) Assembly
GTO Servo Control Box (GTOCP3)
GTOCP3 Control Box Adapter
14" Stainless Counterweight Shaft, 1.875" diameter (M9404-A) and Safety Stop (M12676)
R.A. and Dec. Y-Cable
8' Power Cable (CABLPF)
15' Straight-through Serial Cable (CABSER15)
Allenhead wrench set
CD containing: PEMPro v2 Software and PulseGuide Software, both written by Ray Gralak of Sirius Imaging. Also, PDF of 1100GTO and GTO Keypad instruction manuals
Manual: 1100GTO German Equatorial
Manual: GTO Servo Motor Drive System
Registration Card

1100GTO-AE: 1100GTO German Equatorial Mount with Absolute Encoders
What’s Included:

All items listed above for the 1100GTO, except the GTOCP3 Control Box Adapter and Y-Cable
R.A. and Dec. Absolute Encoders, installed
R.A. and Dec. Readhead with wire harness, standard temperature version, installed
Junction Box and Cables
GTOAE Control Box
GTOCP3/GTOAE Dual Control Box Adapter
Cable from GTOAE Control Box to GTOCP3 Control Box
Power Cable
CD with Absolute Encoder Utility (Windows-based)
All required fasteners
Note: The Astro-Physics Command Center (APCC) software is not included as part of this package. It is available as an optional purchase.
All accessories that are listed as suitable for the 1100GTO are appropriate for this version of the mount, as well, with the exception of the Limit/Homing Switch System, which would not be needed anyway.

1100GTO-AEL: 1100GTO German Equatorial Mount with Absolute Encoders (Extended Temperature Range)
What’s Included:

All items listed above for the 1100GTO-AE, except that the Readheads are the Low Temperature Version.
Note: The Astro-Physics Command Center (APCC) software is not included as part of this package. It is available as an optional purchase.
All accessories that are listed as suitable for the 1100GTO are appropriate for this version of the mount, as well, with the exception of the Limit/Homing Switch System, which would not be needed anyway.

Price and Delivery Information

The 1100GTO with GTOCP3 Control Box is no longer available. Please refer to our website for our most recent model in this size category.

Support

We have prepared some pertinent support documents relating to this mount and many of our other products on our Technical Support page. Please check there first to find the information that you need.

Upgrades and Spare Parts

Check out our Astro-Physics.com website to find accessories, replacement parts or learn about possible upgrades for your mount.

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