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el Capitan 3600GTO

Above: Astro-Physics Computer Controlled German Equatorial Mounts - 1200GTO for scale alongside Model 3600GTO
Each includes GTO Keypad, the GTOCPU3 CPU, and a CD with 'PulseGuide' and full 'PEMPro' v.2 software.
Click on image to see enlarged view.

Literally, the BIGGEST new introduction at Company Seven for 2007!

12 inch Mak-Cass on el Capitan 3600GTO Astro-Physics has become synonymous with unadulterated performance and reliability, balanced with reasonable prices so much so that no other products command premiums on the resale market as does Astro-Physics - scalping may be the sincerest form of flattery. And to its credit, no other product line has achieved such a large installed base of clientele using this class of premium products: their telescopes and computer controlled "Go To" German Equatorial Mounts. It has been in part because of the numbers of these systems being used over the past decades with the frequent interaction with Astro-Physics between its customers, friends, testers, and with Company Seven that has led to this product line becoming so advanced, so quickly. And the fact that Astro-Physics is able to manufacture the quantities of these superb products completely in house helps to constrain prices and make them not only technologically advanced and desirable, but also comparatively affordable.

Introducing 'el Capitan'

And while most of their mounts are solid as a rock with their intended payloads, now we can announce a new German Equatorial Mount that is as solid as a really BIG rock! The 3600GTO (AKA 'el Capitan') is the ultimate solution for imaging with larger transportable instruments or for installations that employ multiple instruments in parallel with an approximately 250 pound (114 kg) combined weight. Of course this is suitable for use in a permanent Observatory setting, for local and or remote control. Please note however, although you might be tempted Astro-Physics does not recommend rapelling off the side of this mount!

Right: Astro-Physics Model 3600GTO German Equatorial Mount with Astro-Physics 12 inch f/12.5 Mak-Cass telescope.
Click on image to see enlarged view.

Astro-Physics 900GTO in Antarctica
Some reasons to consider an AP3600 "el Capitan" mounting for your next large scope:

Originally designed to carry a large telescope in Antarctica for planetary research - the 3600GTO mount had to be reliable even in the most severe environment on the planet while functioning flawlessly 24 hours per day throughout the entire polar night, a night lasting 6 months. Once the mount is installed and the polar night begins, no maintainance can be done to the mount due to the extreme low temperatures and dangerous wind conditions that prevent technicians from working outdoors.

Right: Astro-Physics 900GTO Computer Controlled German Equatorial Mount in Antarctica (94,995 bytes).
Note custom Latitude Wedge betweenthe mount base and pier required to attain proper Pole Alignment elevation here.
Click on image to see enlarged view (284,412 bytes).

Our smaller Astro-Physics "Go To" German mounts have proven themselves in these frigid Antarctic conditions over the past three years. We have had a number of 900GTO and 1200GTO mounts with few modifications from those we sell at Company Seven, running continuously at 'Dome C' in Antarctica and they have proved themselves to be winners. In fact, they are some of the few things that actually work under those conditions where the temperature is so cold that optics shatter and paint falls off tube assemblies like skin shed from a molting snake. The same design philosophy that has overcome these harsh conditions has made the 3600GTO the finest mounting of its class that is available;(follow this link to see photos from Antarctica. On the linked page click on the Photo Gallery menu choice at the bottom of the page, and then scroll down to "Astrophysics place"; click on Turbulence Monitoring; and click on Summer 2003: First Seeing . . . )

October 26, 2007 with the opening of the Advanced Imaging Conference in San Jose, California Astro-Physics was delighted to announce the unveiling of a truly impressive new German Equatorial Mounting: the 3600GTO, nicknamed "el Capitan" for its solid, rock-like stability. The 3600GTO will be the new flagship of our Astro-Physics mount lineup, with almost double the capacity of the 1200 series mounts! This mount is sure to become a favorite of imagers and observers wielding larger astronomical instruments for truly critical work.

The prototype 3600GTO mount will soon be taking its place in Dome C in Antarctica where it will carry on in the research that was started with several of our 900 and 1200 mounts. Full scale production will begin soon, and the frequency and quantity of mounts made will depend to a large extent on the response from the astronomical community at large. While we await our own 3600GTO, we invite you to see the examples of all Astro-Physics telescopes and other mounts at Company Seven's showroom, or contact Company Seven, the Americas only full line Astro-Physics showroom!

The 3600GTO mount is designed to be:

  • Large, robust, rugged, simple modular design that will be easy to fix if something should go wrong
  • The design has the same DNA as our smaller mountings, uses time-proven components that have withstood the test of time under all conditions, even in temperatures as cold as -70C.
  • Extremely smooth and accurate dual servomotor-worm gear drive, designed for all astro-imaging situations
  • Machining craftsmanship and beautiful mechanical design second to none
  • Ability to carry very large and heavy scopes comfortably
  • Will have many options for enhancing the operation and accuracy of the mount for remote imaging
  • On-going development of the software and hardware will always be available to upgrade older mountings to bring them up-to-date
  • Simple mechanics make adjustment easy and accurate
  • Feature loaded software is intuitive and powerful
  • Intensive support via direct communication with our technicians - we have never failed to fix a problem, and will always help someone get the most out of their mount
  • More than thirty years of experience in making precision equipment for the most demanding amateur and professional astrophotographer

The 3600GTO uses the tried and true Astro-Physics Go-To Computer Control System.

  • Lead-free: all electronics and components are completely free of lead complying with even the most stringent European standards (of course the US Government does not care about this - yet). This includes wiring for the motor harness, the GTOCP3 Control box, Keypad and all cables. All functions of the lead-free GTOCP3 control box are the same as the original version.
  • GTOCP3 Servo Motor Control Box: increased protection on all input lines, larger memory chip, and additional commands for mount control.
  • GTO Keypad: unique keypad has evolved over the years to include a new circuit board with larger memory capacity, LED fiber optic backlit panel for greater longevity and quieter operation and epoxy coated elastomeric keys. The impact absorbent Keypad Protector is furnished with each keypad.

Flexible and Transportable
Extremely solid, rugged, high payload capacity mount. Yet the equatorial head comes apart into two components facilitating transport and field setup. The RA axis and base assembly alone weigh just over 120 lbs and so you would not want to transport it as your routine mode of operation, but it can certainly be done for special occasions. Because of this mount's size and weight, we do recommend that field assembly be done by at least two people trained and working together.

Portable Pier available
As illustrated in the photo at right, our friends at ATS (Advanced Telescope Systems) have developed a portable pier for use with this large mount. The pier is extremely rigid, and it folds up for transport.

Operate with 12V battery
You can take the 3600GTO to the darkest skies and power it with a commonly available, heavy-duty, deep-cycle marine 12 Volt battery. In the observatory, we do recommend the use of a Regulated Power Supply with a rating of a minimum 10 ampere regulated power supply like our 15V, 10 amp power supply (PS15V10AC).

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.

Customer commenting on his Astro-Physics 1200GTO that uses the same control system:

". . . 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

The full 360 degree rotation of both of the 3600GTO's axes also allows this mount head to be installed onto an astrographic pier for complete freedom from movement restrictions.

Easy alignment for non-critical viewing
Can align with am optional Polar Alignment Telescope to quickly zero in on the pole for most non-critical observing or to get close before tweaking in for CCD. Our built-in software routine allows polar alignment in the daytime for solar observing, viewing planets at twilight, and drift alignment on bright stars before nightfall.

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. The mechanical design of the mount is extremely simple and straightforward, allowing easy adjustment by anyone - no need to have a mechanical engineering degree to service the mount.

Through-the-mount cabling capability
This mount is designed to allow cabling to be run through the axes shafts for tangle and clutter free operation. Cables from cameras, guiders, dew heaters and the mount's own servo drive cables can all be run through the mount's cavernous 4" shafts where they are out of the way and where they won't ever get caught or tangled during your imaging session. Ports have been included for the mount's servo cables. Custom cabling will be available for a variety of accessories.

Massive and sturdy telescope mounting platform
The telescope attachment system of the 3600GTO was custom designed for strength, rigidity and flexibility. A special dovetail system was engineered for the mounting that allows for accurate balancing with a huge variety of instrument configurations. The dovetail plate's four clamps will grip the largest instrument solidly. Safety slots coupled with the sliding bar's safety stop will help keep accidents from happening. The dovetail system can be set up for tip-in or slide-in of the dovetail sliding bar. For permanent installations, a series of matching through-holes in the dovetail and sliding bar allow the setup to be bolted into its final position once adequate balance is achieved. This system provides the convenience of a dovetail with the security of a fixed mounting plate. As an added feature, the dovetail plate offers a cabling port on the eyepiece end for taking advantage of the large cable path that goes through the mount.

Standalone Operation: external computer not needed
The keypad is basically a handheld computer with all of the features, functions and databases you need to tour the universe night after night. The vacuum-fluorescent display with a temperature range of -40 degrees F (and C, they are the same in this instance), allows hardy observers to use this mount on cold winter nights.

Free Keypad Firmware Updates
As new firmware versionsare released in the future, you can upgrade your keypad directly from the Downloads section of Astro-Physics website - free of charge!

Remote Control with personal computer, if desired
All functions of the servo drive can be commanded from a laptop or desktop computer using PulseGuide or popular planetarium software. Depending on the features of the program, you can position your telescope, center your image and control tracking rate, remote focusing, reticle brightness and park at the end of your observing session. The GTOCP3 control box provides two RS-232 inputs so that you can operate the mount with two programs simultaneously. For instance you can control most mount functions with PulseGuide that takes full advantage of our firmware protocol, and use TheSky as your planetarium program. If your computer does not have serial port inputs, there are many USB to serial port adapters available on the market.

Some examples of currently available software include:

  • PulseGuide by Ray Gralak (included with the 3600GTO) Note: a new, more robust remote control software is currently under development
  • Software Bisque's suite which includes TheSky Astronomy Software, CCDSoft CCD Astronomy Software, TPoint Telescope Pointing Analysis Software and Orchestrate Scripting Software.
  • Starry Night Pro by Imaginova (stocked by Company Seven)
  • Earth Centered Universe by David Lane of Nova Astronomics
  • SkyMap Pro by Chris Marriot
  • ACP Observatory Control Software by DC-3 Dreams - Robert B Denney
  • Any software that is ASCOM compliant.

Or, write your own computer program with the Astro-Physics GTO Protocol for the GTOCP3 Control Box.
This Adobe .pdf document is freely available from our Astro-Physics Library to those who would like
to write their own computer program for controlling the mount.

Precise Mechanical Fabrication Highly accurate mechanics
Using modern CNC machining techniques Astro-Physics manufactures all components in house to a high precision level. This 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.

Their machinists are among the most skilled available anywhere, and the pride they take in their work should be an example to all who work in manufacuring. And all mount assembly is directed by a life-long astronomer with twenty years of experience at Astro-Physics!

Worm gear accuracy
Critical worm gear accuracy is maintained by special machining techniques developed at Astro-Physics after extensive studies, actual field operation and many years of experience making precision mounts. Their worm accuracies are second to none and are guaranteed to be 5 arc seconds or less, peak-to-peak. The periodic error of each mount is verified during extensive testing procedures. Performance is further optimized by characterizing the error using a special version of PEMProAP and downloading the appropriate correction into the mount's GTOCP3 before it leaves Astro-Physics. With good alignment and PEM training with the Keypad or PEMPro, it is quite practical now to achieve unguided CCD images with today's hi-resolution cameras coupled to a large telescope.

Easy to Adjust and Maintain
The design of the 3600GTO is straightforward with modular construction and no complicated internal wiring. Astro-Physics will provide information in the Technical Support section of their website pertaining to typical adjustment issues and this may be mirrored at our own Astro-Physics Library.

If the electronics ever need servicing since the system is modular it will be matter of logical reasoning to diagnose the problem, isolating it down to a particular module (the GTOCP3 Control Box, the Keypad, a Cable, ect.) and since these can each be easily removed it will be a simple matter to pull one or more and return them to Company Seven or to Astro-Physics for further testing and remedy.

Polar alignment is extremely precise due to the heavy-duty adjusters provided for the fine control positioning of altitude and of azimuth. Once set to the desired position, then the system precisely locks down each axis with zero alignment shift for an unprecedented ability to achieve that "perfect dead on" polar alignment that is so critical to the best imaging and the most accurate Goto's.

Servo Motor Drive
The drive system uses TWO high-quality Swiss DC servo motors for each axis 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 drive. The dual motor system smooths out the drives even further by applying an averaged power curve to the drive system. In preliminary testing this has resulted in PE curves that are noticably smoother than the already phenominal curves on our 1200GTO mounts. The system can be accurately controlled over a speed range of 4800:1 which allows 0.25x sidereal for guiding to roughly 720x sidereal for 3 degrees per second maximum slew rate.

The circuit draws well under an amp when tracking the stars, 3 to 5 amps with both axes slewing and requires only 12 volts to operate (15 volts is recommended). This servo drive will satisfy the requirements of the sophisticated, advanced astrophotographer, yet is easy for the casual, visual observer to use.

Product Support
All Astro-Physics mounts are supported by a dedicated staff at Company Seven and at the factory 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 online at the Ap-gto user groups in the Yahoogroups forum. The user group is comprised of 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.

Integrated Pier Adapter
The Pier Adapter for the 3600GTO has been integrated into the mount's design and incorporates the design principles of the Precision Adjust Rotating Pier Adapters and in an innovative twist this puts the Super Heavy Duty Azimuth Adjuster UNDER the BACK of the mount where it is both conveniently located for fine polar alignment and remains out of the way. Polar alignment is smooth and easy, and the system locks down tight with no unintended movement.

PulseGuide™ Software
Special note: Ray Gralak, the author of PulseGuide, is currently working on a new piece of software that will combine the Astro-Physics ASCOM driver, all the features of PulseGuide, and additional features including a powerful planetarium. The new software will have a new name befitting its vastly increased capabilities, and will replace PulseGuide when it becomes available. In the mean time, here's the lowdown on the existing PulseGuide software:

PulseGuide is a stand-alone Microsoft Windows (98, ME, 2000, NT4, XP and Vista) utility that provides complete remote control of Astro-Physics 400GTO, 600EGTO, Mach1GTO, 900GTO, 1200GTO and the 3600GTO mount. It derives its name from its most distinctive feature, pulse guiding, which can improve unguided tracking. Specifically, it can help correct tracking errors caused by polar misalignment and atmospheric refraction. You can also train PulseGuide to track objects moving relative to the stars, such as asteroids, comets, and the moon. In addition to pulse guiding, PulseGuide also has many useful utility features. With just a few exceptions, it supports the entire serial Astro-Physics command protocol.

PEMPro v. 2.0 Software - FULL Version!
PEMPro (Periodic Error Management Professional) is a Windows software application developed by Ray Gralak that makes it easy to characterize and reduce periodic error. While the periodic error of your 3600GTO will be 5 arc seconds or less, you can reduce it even further to maximize performance without auto-guiding. PEMPro v. 2.0 is the latest version of PEMPro and includes exciting new features like the "Polar Alignment Wizard" to quickly, accurately and easily dial in your polar alignment. The software will be included with all new 3600GTO mounts.

Mechanical Features

  • All machined mounting made from aluminum bar stock and stainless steel.
  • All fasteners are stainless steel.
  • Motors and all electronic components are enclosed.
  • Polar and declination axes come apart with relative ease for manageable transport.
  • Fine altitude and azimuth adjustments for quickly and accurately zeroing in on the pole in the field.
  • Base fits into 12 inch diameter pier with 0.25" wall thickness.

Worm Wheels: Aluminum - 13" (330mm), 256 tooth
Worm Gears: Brass - 1.41" (35.8 mm) diameter
Axis Shafts: 4.72" (120mm) diameter with 4.02" (102mm) clear inside diameter
Axis Bearings: 7.09" (180mm) diameter deep groove ball bearings
Worm Gear Bearings: 1.57" (40mm) angular contact ball bearings
Latitude range: 15 to 70 degrees
Azimuth adjustment: ± 7 degrees (total 14 degrees)
Motors: Swiss DC servo controlled - 2 motors per axis
Optional Saddle: 12.9" x 22" (328 x 559mm), 15 lbs. (7kg) dovetail receiver with four integrated clamps, safety slots and bolt-through locking feature. Optional auxilliary control panel available.
Optional Dovetail Sliding Plate: 9.9" x 22" (251 x 559mm), 9 lbs. (4kg) with universal hole patterns and safety stops.
Rated Payload Capacity: Approximately 250 lb. (113 kg) scope & accessories, depending on length
Weight of equatorial head: Equatorial head without counterweight shaft or counterweights: 205 lbs. (93 kg).
Dec Axis = 84 lbs. (38kg), RA Axis/Base Assembly = 121 lbs. (55kg)
Counterweight shaft (estimated): 30 lbs. (14kg)

* Specifications and features are preliminary and subject to change.

Recommended Accessories

  • 15V 10 Ampere Regulated Power Supply with Cigarette Adapter
  • Santa Barbara Instrument Group All CCD Star Tracker/Imaging Systems
  • Telescope Interface Cable (TIC) for SBIG Autoguiders and CCD Imaging Cameras
  • Advanced Telescope Systems (ATS) Portable Piers
  • Stainless Steel Counterweights for 2.5" diameter shaft
      Counterweight sizes are yet to be determined - tentatively 25 lbs. each
  • Special 28" 1200 GTO Series Counterweight Shaft (M12661-A)
  • Power Cord for Pentax 6x7 Camera (CORD01) -->
  • Polar Alignment Scope (PASILL4)
  • Mounting Rings
  • Company Seven offers optional deluxe fitted Airline Transport Approved cases to facilitate transport and shipping (see example below).

    Astro-Physics 900 Mount Declination Housing (left side shown), with GTO Keypad Controller, and Counterweight Shaft in optional Company Seven ATA case (94,326 bytes) Above: Company Seven ATA Case 1 of 2 for Astro-Physics Model 900GTO Mount.
    This holds the Declination housing with GTO Keypad Controller and Counterweight Shaft and some accessories (94,326 bytes).


Contents Copyright 2008 Astro-Physics and Company Seven All Rights Reserved