Astro-Physics 1100GTO with GTOCP4

Throughout  the years, the Astro-Physics design team has sought to continually improve our product line, particulary as the technological demands for ever more precise equipment has increased.

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.

Auto-Adjusting Motor/Gearboxes

Our new motor/gearboxes were designed to be more responsive for precision astro-photography, while at the same time making it super easy to use and adjust. Here are some key features:

Spring-loaded worms maintain full contact under all guiding and slewing conditions

Automatic setting for worm mesh requires no adjustments over long time periods

• Very easy to do precision balance by new mechanism which allows full backing off the worm from the worm wheel

• Very low backlash gear train eliminates Dec reversal delays and provides high position accuracy during guiding

  Here are some changes that you may find useful in addition to the GTOCP4 and Auto-Adjusting Motor/Gearboxes discussed abovel:

• Like the previous GTO mounts, the GTOCP4 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 commercial 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 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 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 GTOCP4 Control Box.
  
  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 1100GTO uses the same GTOCP4 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. 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.

Specification: