German Equatorial Mount (1600GTO) GTOCP4 /Auto-Adjusting Motor/Gearboxes
Why a 1600GTO?
Thirty plus years of mount design and building expertise has been employed to engineer and manufacture 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 precision polar scope to meet the needs of even the most demanding astro-imager or visual enthusiast.
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 1200" has 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 position.
- 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 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.
- 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.
- 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.
GTOCP4 Servo Drive System
Like the previous mounts, the GTOCP4 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 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 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 GTOCP4 Control Box. Simply use the optional 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.
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. The 1600GTO uses the same GTOCP4 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. However, the absolute encoder function is only available in the control boxes sold with those mounts. Extensive information regarding the GTOCP4 can be found here.
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. Click here for detailed information regarding features and functions of the Keypad.
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.
- What's Included?
- Polar Fork / Right Ascension Axis (R.A.) Assembly
- Declination Axis (Dec.) Assembly
- GTO Servo Control Box (GTOCP4)
- 19.5" Stainless Counterweight Shaft, 1.875" diameter (M12601-D) and Safety Stop (M12676)
- R.A. / Dec. Y-cable
- Power Cable Set for GTOCP4, includes 6' Cable with PowerPole Connector, 18" Cable with Cigarette Lighter Plug and 18" Cable with Ring Terminals (CABPP4SET)
- 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 1600GTO and GTO Keypad instruction manuals
- Manual: 1600GTO German Equatorial
- Manual: GTOCP4 Servo Motor Drive System
- Registration Card
|Electronic components||Rated for industrial and automotive applications|
|Motors||High-torque, 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||GTOCP4 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|
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|