1150GTO

GTOCP6 Control System

Our GTOCP6 control system combines the precision performance of the Renishaw Resolute Absolute Encoder with the whisper-quiet motion of brushless micro stepper motors to produce a very accurate observatory-grade mount that can also be set up in just a few minutes in the field. The mount can be operated manually via the clutches or electronically with the encoder loop providing the pointing and tracking functions.

• Use of Absolute Encoders means that the mount always knows where the axes are pointing and doesn't need to establish home on power-up.
• The mount can be operated manually via the clutches or in full GoTo mode via keypad or external software.
• Absolute Encoders are extremely accurate in slewing, pointing, tracking, guiding. Periodic error and backlash, reversal delays in Dec are eliminated.
• Rapid feed-forward servo loop stiffens the axes against outside disturbances such as cable drag and wind loading.
  
  
• Both axes can be run at custom tracking rates from sub-arc second motions per hour to 1000x sidereal.
• The GTOCP6 brushless micro stepper motors can be run from 24 volts to 12 volts with max slewing to 1200X (5 deg/sec).
• The power to the motors is self-limiting and cannot cause any kind of damage to the windings or the electronics, even when in a stalled state.

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. The new V5 version includes modeling routines for pointing, tracking and orthogonality.  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. The Keypad is an ideal choice for these users.

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.

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. 

 

1150GTO and Renishaw Absolute Encoders Option

1150GTO Tracking Performance with Absolute Encoders - PE = 0.19 arc seconds

All of our Mach2, 1150GTO, and 1600GTO mounts with Absolute Encoders installed have always used the Renishaw Resolute Absolute Encoders for precise positioning and tracking. What are the main differences between the Renishaw and other less expensive relative encoders?

Lab Certified Accuracy! 
The Renishaw encoder accuracy is verified against a laboratory standard. Each ring comes certified with its own calibration measurement. The maximum guaranteed error on these rings translates to less than 1/2 arc second per hour tracking error.

Highest Resolution for Unparalleled Tracking Accuracy!
The Renishaw Resolute read-head interpolates a special barcode that is engraved on the matching stainless steel ring into 67 million individual addresses. Every address is unique and fully reproducible down to sub-arc second levels. This is not possible with any relative encoder system.

Ripple and Resonances – NOT with Astro-Physics!! 
Relative encoders use a simple ring that has engraved marks with separations on the order of 60 to 100 arc seconds between ticks. In order to achieve sub-arc second resolution, the gaps between these marks are filled in electronically by a method known as interpolation. Even the best interpolation methods have errors on the order of 5% (3 to 5 arc seconds). When used in a telescope drive system these relative encoders introduce a fast moving ripple in the RA tracking rate of 3 to 5 arc seconds, although the average or RMS value of this error can be quite low.

These peak excursions cause stars to move slightly back and forth in the RA direction during sidereal tracking. This tracking ripple can remain hidden when imaging with short wide-field scopes, but will manifest itself when using long focus instruments for high resolution work. It is generally a fast moving error, so it cannot be guided out.

No Sub-divisional Error! 
Because of the ever present interpolation error (SDE) with low-cost relative encoders, we decided long ago that we would not use them for tracking. Renishaw absolute encoders use a different type of interpolation system that smooths out the SDE to a level that is not detectable. There is no mechanism for a relative encoder to remove the SDE.

Never Needs Homing. Simply Polar Align; Power Up; and GO!! 
An absolute encoder never needs to be homed. It is always home the minute power is applied. It always knows where it is and transmits the exact shaft position to the control box at all times.

Dependability to Astro-Physics Standards!
We have used Renishaw encoders for many years on our larger mounts, both in portable setups and in observatory remote installations. They have been totally reliable. Renishaw encoders are also considered to be the gold standard in the machine tool and robotics industries where precision is required. Yes, they are much more expensive than a simple relative encoder, but for the type of accuracy required in a telescope mount, there is nothing out there that comes close. We know, we have been evaluating options for years.

Benefits of Absolute Encoders

The utility of absolute encoders varies from one mount brand to another.  Some manufacturers make very limited use of encoders and use relative (not absolute) encoders to provide a potential benefit to tracking and nothing else.  In regards to the 1150GTO, the benefits are:

• Sky-Aware Axes - The mount always knows where it is pointed regardless of power loss, movement of the axes when the power is off, bumping the mount or wind movement. 
• No rehoming is required for remote locations should there be a power loss.
• Periodic error is fully corrected. No need for occasional PE measurement curves.
• Zero backlash in both axes for precision guiding.
• Dual-axis absolute encoders allow for variable tracking that automatically adjusts for refraction parameters.
• Very accurate pointing makes it easy to find very faint objects.
• Very precise tracking such that unguided imaging may be accomplished with an appropriate optical/imaging setup.
• Very precise guiding, if needed, with instant response in both axes.  Guiding is only needed to correct for optical/imaging train issues, not mount issues.
• Corrects for polar misalignment and repeatable mechanical flexure.
• Very precise dual-axis tracking is very important for high precision tracking on objects like comets, asteroids, artificial satellites, where the mounts use a "self-guiding" function based on orbital elements.

We invite you to review the additional technical information regarding the encoders to find out what they can do for you.  

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
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 16.5" (419 mm) usable length, incl. large machined safety stop knob. Optional 8.675" (220 mm) shaft extension available. Weight 13 lb. (5.9 kg)
Weight of mount	R.A. axis/polar fork: 31.7 lb. (14.4 kg) Dec. axis: 21 lb. (9.5 kg)
Capacity	Approximately 125 lb. (57 kg) of scope and accessories, 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.
Instrument mounting interface	Refer to list of suitable mounting plates
Pier adapter base diameter	7.730" (196.3 mm) Base. The base is an integral part of the mount and azimuth adjuster.
Origin	Designed and manufactured in the USA

  

GTO Drive Specifications

Electronic components	Rated for industrial and automotive applications
Motors	Brushless micro stepper motors, enclosed in machined aluminum housing
Optional Absolute Encoders	R.A. and Declination axes, Sky Aware axes means you can loosen the clutches and reposition, the mount will know where it's pointing.
Periodic error	Native - +/- 3.5" before correction Absolute Encoders - 0.19” arc seconds peak-to-peak, 0.05 RMS
Servo Motor Control Box	GTOCP6 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 requirements	Nominal 12 to 24 Volt DC supply, minimum of 5 amps continuous Tracking: 22 Watt max;  Slewing 50 Watt max
Maximum slew speed	5 degrees / second

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.  You will be able to link to a full-sized view of this chart.

Control Options for Astro-Physics Mounts

Astro-Physics control boxes support a wide range of connectivity.Physical connectivity includes RS232, USB, ethernet and WiFi. The included state-of-the-art ASCOM driver supports connectivity with all ASCOM-compliant software, including NINA, Sequence Generator Pro, Maxim DL, TheSky, Voyager, and many others. The Indi driver enables connectivity to KStars, Ekos, ASIAir, and other Indi-specific apps (Indi driver is developed and supported by third party) 

1150GTO German Equatorial Mount

• 1150GTO Equatorial Head with Dual Absolute Encoders 
• GTO Servo Control Box (GTOCP6)
• Control Box Adapter (CBAPT)
• 13.675" Stainless Steel Counterweight Shaft, 1.875" (47.6 mm) diameter with Machined Safety Stop Knob (M12676)
• 6' Cable with PowerPole Connector (CABPP6) and Clip
• 1/4-20 Machined Knob Kit (M1485KBKIT)
• Allenhead wrench set
• ASCOM driver, available by download
• APCC Software, Pro version (APCC-PRO) license included
• Thumb Drive containing: PDFs of manuals and other handy utilities.
• Manuals: 1150GTO German Equatorial and GTOCP6
• Registration Card
• Power supply NOT included, must be purchased separately

Items You will Need for Your Mount

• 12-24V DC power supply
• Counterweights: Stainless Steel Counterweights - 5, 10, 18 lb.  (5SCWT, 10SCWT, 18SCWT, 30SCWT188) (due to larger diameter 30SCWT188 is not recommended for use at top of the shaft)
• Mounting Plates: DOVEDV10 or DOVELM162
• Refer to USB 3.0 Internal Cable Considerations below to plan your cable requirements.

Support Pier and Tripod Options

Minimum 8" diameter recommended

Permanent Piers

• Advanced Telescope Systems ATS 8" permanent pier
• requires 119FSA-FP flat surface adapter
• SkyShed 8" permanent pier
• requires 119FSA flat surface adapter
• Build your own concrete pier using the 119FSA flat plate adapter and adapter from Dan's Pier Plates

Always contact third party vendors to confirm configuration, pricing, and availability.

 

Portable Piers and Tripods

• Astro-Physics Portable Pier - 8" diameter, available heights 32",42",48"
• Advanced Telescope Systems (ATS) 8" Portable Pier
• requires 119FSA-FP flat surface adapter
• Losmandy HD Tripod
• requires 119FSA flat surface adapter

Always contact third party vendors to confirm configuration, pricing, and availability. 

Additional Accessories to Consider

• 24V DC Power source: 
• GTO Keypad with 15' Coiled Cable and Keypad Protector (KEYVFK2)
• Right-Angle Polar Alignment Scope with Illuminator (RAPAS), requires attachment Bracket 
• Bracket to Attach Right-Angle Polar Alignment Scope Adapter to 1150GTO Mounts  
• Pier Accessory Trays (TRAY06 and TRAY06H) and Support Bars (TRAYSB1 and TRAYSB)
• Side-by-Side Dovetail Plates for D-Style Dovetail Saddles (SBD13SS, SBD18SS)
• 10.7" x 1.875" Counterweight shaft (M1053-A) to use with very small scopes. 
• 16.975" x 1.875" Counterweight Shaft (M9404-B) for heavier loads rather than adding a shaft extension. 
• Alligator Clips with APC Fuse to PowerPole Connector (CABPPAL)
• Powerwerx In-line Watt Meter shows volts, amps, watts, amp-hours, watt-hours. (CABPPWM)

USB 3.0 Internal Cable Considerations

As mentioned, the mount includes an internal USB 3.0 cable for your convenience. It is important to remember that passive USB 3.0 cables (including the 2 foot internal cable) can be no more than 9 feet (3 meters) in length from a powered port and passive USB 2.0 cables can be no more than 15 feet (5 meters) in length from a powered port. With that in mind, you will need to plan your computer cabling carefully. With USB, shorter is better.  These are our current recommendations:

Connecting Computer to Mount Internal Input
These connections are made to the 1150GTO Back Plate on the RA axis.

Using USB 3.0 Active Cable and Short USB Cable

• USB 3.0 Active Cable (male A-to-female A).  Example: Tripp Lite USB 3.0 Active Extension Repeater Cable (USB-A M/F) 
• USB 3.0 male A-to-male A Cable for Data Transfer (short cable).  Example: UGREEN USB 3.0 Type A Male-to-Type A Male Cable for Data Transfer, 1.5-ft

Connecting Mount Internal Output to Communication/Power Hubs
These connections are made to the Dec axis Top Plate just under your mounting plate.

Using Pegasus Astro Ultimate Powerbox and Pocket Powerbox Advance

• USB 3.0 male A-to-male B Cable (standard)
• Custom 12 volt Cables with Anderson Powerpole Connector to XT-60 Female Connector (Ultimate Powerbox) or RCA Male Connector (Powerbox Advance).  It is recommended to use a 16 to 18 AWG cable. 

Using USB 3.0 Communication Hub and RIGRunner Power Distribution

• USB 3.0 male A-to-male B Cable (standard)
• USB 3.0 Powered Hub.  Example: Gearmo USB 3.0 4-Port Industrial Metal Hub w/15KV ESD Protection
• Powerwerx Power Distribution
• Custom 12 volt Cables with Anderson Powerpole Connectors
• 4 Position Power Distribution Block for 15/30/45A Powerpole Connectors
• West Mountain Radio RIGrunner 4005
• Cat6A Ethernet cable - standard Cat6A cable

Using Primaluce Lab Eagle Communication Hub and Power Distribution

• USB 3.0 male A-to-male B Cable (standard)
• Primaluce 12 volt Power Cable to Anderson Powerpole Connector

 

Availability

The 1150GTO is in pre-production. Please complete the 1150GTO Notification Request Form if you would like to be notified when a mount is available for you to order.