ASTRO-PHYSICS
3600GTO German Equatorial Mount (3600GTO)
and
3600GTO German Equatorial Mount with Precision Encoder (3600GTOPE)
" el Capitan "
Featuring GTO Servo Drive System
Includes GTOCP3 Control Box, GTO Keypad and CD with PulseGuide and PEMPro v.2 software (full version)
Solid as a rock!
El Capitan is the ultimate imaging platform for large instruments like the 20" or 24" Ritchey-Cretiens by RC Optical, PlaneWave CDK17 or CDK20,
RC20 or RC24 by Optical Guidance Systems or instruments of similar size. Setups that employ smaller multiple instruments would also be ideal.
Why a 3600GTO ?
The 3600GTO is the culmination of over 30 years of experience designing and building mounts at Astro-Physics for the amateur and professional astrophotographer . We now offer two versions of this mount to suit your application. The version designated as 3600GTO is the standard version and the 3600GTOPE includes the built-in Precision Encoder System. Both versions of the mount include these features:Mechanical Features
Image past the meridian.| . . . 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., More… (commenting on his 1200GTO that uses the same control system. All A-P mounts have this feature!) |
Full 360 degree rotation of both axes.
The full 360 degree rotation of both of the 3600GTO's axes also allows this mounting to be placed onto an astrographic pier for complete freedom from movement restrictions.
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Through-the-mount cabling capability. We designed this mount to allow cabling to be run through the axis 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" hollow 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. Additional ports can be added by the user, as needed. |
Components are modular and easy to maintain. 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, 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. |
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Easy to Adjust and Polar Align. Precise polar alignment can be achieved easily using the precision adjusters for both altitude and azimuth. The system locks down 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 go-to slews. |
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Transportable |
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Precise Mechanical Fabrication.
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Highly accurate mechanics. Our machinists are among the most skilled available anywhere, attending to the smallest detail to ensure a precision instrument. The finishing department assures that all parts are deburred, sanded, polished and painted to provide an exceptional aesthetic appearance. Our mount assembly is directed by a life-long astronomer with almost 20 years of experience here at Astro-Physics! All of our production personnel take great pride in their work and are true craftsmen and women. |
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. Our worm accuracies are second to none
and are guaranteed to be 5 arc seconds (+-2.5 arc sec.) or less, peak-to-peak.
The periodic error of each mount is verified during
our intensive testing procedures. We optimize performance further 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.
Pre-programmed with PEMPro
Periodic error corrections for each individual mount are optimized during extensive testing, which results in excellent performance right out of the box. 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. However, in the process of testing the RA axis with a special version of Ray Gralak's PEMPro developed specifically for our test equipment, we generate a unique, optimized PE curve for each individual mount that we program back into that mount. Simply use the Keypad or PulseGuide software to turn PE Correction "on," and you will see results are even better than our published 5 arc second spec!
If your application requires the highest possible levels of tracking accuracy, you may want to consider the Precision Encoder System described below.
| Worm Wheels-RA & Dec | 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 | Approximately 14 degrees (+/- 7 deg.) |
| Motors | Swiss DC servo controlled - 2 motors per axis |
| Instrument Mounting | Declination hub has ten 3/8-16 tapped holes on a 12.000" bolt circle. Click here for a detailed drawing. (PDF) |
| Capacity | Conservatively rated for 300 lbs (not including counterweights). Please feel free to call and discuss your application with our staff. |
| Counterweight Shaft | 2.5" (6.35 cm) diameter, 31.5" (80 cm) total length, 30" (76 cm) useable, 42 lbs. (19kg). Twelve of the optional 30# counterweights will fit onto this shaft. Includes large, machined safety stop. An optional shaft extension (M3655) is also available. |
| Diameter of Base | 11.480" (29.16 cm), fits into 12 " outside diameter pier with 0.25" wall thickness. |
| Weight | Equatorial head (without counterweight shaft or counterweights): 205 lbs. (93 kg), Dec axis is 84 lbs. (38kg), RA axis and base assembly is 121 lbs. (55kg) Counterweight shaft: 42 lbs. (19kg) |
Servo Motor Drive
The drive system uses TWO high-quality Swiss DC servo motors for EACH axis controlled by a microprocessor in the GTOCP3 control box. The encoders on these motors provide a resolution of 0.05 arc seconds per step for incredible pointing accuracy. Tracking is very smooth, noticeably smoother than any stepper motor drive or inexpensive servo drive. The dual motor system smoothes 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 noticeably smoother than the already phenomenal curves on our 1200GTO mounts. The system can be accurately controlled over a speed range of 4800:1 which allows 0.25x sidereal for manual 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 (15-18 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.
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 GTO Keypad is a self-contained computer that serves as the communication center for the operation of your GTO mount. 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.
All of our electronics are now lead-free. Astro-Physics believes that we who love the night sky should also love and protect our good earth. Please refer to GTOCP3 Control Box and Keypad for Servo Drive for more detailed information.
For reliable operation in your observatory, we recommend that you use a minimum 10 amp filtered, regulated power supply like our 15V, 10 amp power supply (PS15V10AC). For lighter, well-balanced loads, you can use a commonly available heavy-duty, deep-cycle marine 12V battery.Flexible Control with either Keypad or Personal Computer
Keypad OperationPlease note that the Precision Encoder System is only included when you order the 3600GTOPE version of the mount. It is not included in the standard version (3600GTO).
A precision encoder installed in the RA axis provides feedback to the servo to eliminate periodic error to a level below 1/2 arc second for long period exposures. This feedback system eliminates periodic error by monitoring the actual output speed of the RA axis using this encoder ring to continuously adjust the speed of the servo motor, which keeps the axis rotating at a very precise and constant rate.
Preliminary test results on the new 3600 mount with optional feedback encoder have exceeded all our expectations. The measured tracking error was well below 1/2 arc second for a 20 minute time period. With this option, it is now practical to do long period unguided imaging with a fixed setup where other sources of drift (due to polar misalignment, tube flexure, etc) have been minimized or eliminated.
Astro-Physics has pioneered the use of precision encoders, normally used in the machine tool industry, to help you achieve optimal results during unguided or guided astrophotography. The system has been under test since late 2007 and we invite you to review our test data in the document entitled: Precision Encoder for the 3600GTO. We have also anticipated the questions you may have, i.e. What does the encoder do? and How does the encoder do this? and have provided these answers for your review.
The operation of the encoder does not interfere with any external guiding, centering or slewing commands sent by the keypad, CCD camera or external software. Its only function is to keep the axis tracking precisely at the sidereal rate, and will also follow any variable rate that is programmed into the servo for purposes of countering atmospheric refraction and other sources of drift.
To further refine the unguided error of the mount, we are adding an all-sky tracking rate to the software, which will minimize RA drift everywhere in the sky. This will allow significant unguided exposure times with a well polar-aligned mount.
PulseGuide™ Software
Please note: Ray Gralak, the author of PulseGuide, is currently working on a new software program that will combine the Astro-Physics ASCOM driver, all the features of PulseGuide, plus additional features. The new software will have a new name befitting its vastly increased capabilities (tentatively the Astro-Physics Command Center), 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 Windows (98, ME, 2000, NT4, XP and Vista) utility that provides complete remote control of Astro-Physics 400GTO, 600EGTO, 900GTO, 1200GTO and 3600GTO mounts. 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. More ....
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 (+-2.5 arc sec. ) 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. More
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Optional Accessories To Enhance the Performance of Your Mount
Limit/Homing Switch System for the 3600GTO (36LSS)
Optional switches can be installed to control operation past the meridian and for homing. The Limit/Homing Switch System can be used as a simple electronic switch or can be used in conjunction with software to establish limits. All mounts will be drilled and tapped to accept this option, which can be added as an upgrade later and installed by the customer. Please refer to the document entitled: Limit/Homing Switch for the 3600GTO for a discussion of these options.
| 36LSS | $530.00 | in stock |  |
| 30 lb. (13.6 kg) Counterweight for the 3600GTO (30SCWT) |  |
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This stainless steel counterweight was designed to fit onto the 2.5" diameter shaft of the 3600GTO. It features a spring-loaded, recessed lock knob and measures 7.9" in diameter by 2.5" thick. |
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22" Dovetail Saddle Plate (DOVE3622) and 22" Dovetail Sliding Bar (SB3622) for the 3600GTO
The massive and sturdy two-part telescope mounting system provides the convenience of a dovetail with the security of a fixed mounting plate. It was custom designed for strength, rigidity and versatility.
The saddle plate (shown in the photo to the right) was designed as a female dovetail and features four spring-loaded clamps that will grip the largest instrument solidly. It can be attached to the mount in three possible positions – centered, forward or back depending on the balance point of your instruments.
The robust male dovetail plate pictured at left features a myriad of holes throughout the entire length that can accommodate a variety of instrument configurations at various balance points. Instruments include the Planewave CDK telescopes and any mounting rings that have the Astro-Physics hole spacing of 3.2” . We also offer hole spacing of 3.5”, 5.5” and 7.45” from one end of the plate to the other. You can also use two (or even three, depending on instrument size) 16" Dovetail Plates (DOVELM162, new style introduced February 17, 2009) in a side by side configuration for multiple instruments. These plates are drilled to attach directly onto the SB3622. They also features new lock-down knobs that can be firmly tightened with an allen wrench.
The dovetail system can be set up for tip-in or slide-in of the dovetail sliding bar. Safety slots on the saddle plate coupled with the sliding bar's safety stop will help keep accidents from happening.
For permanent installations, a series of matching through-holes in the saddle and tapped holes in the sliding dovetail plate allow the setup to be bolted into its final position through both plates once adequate balance is achieved. As an added feature, the dovetail plate is drilled on the eyepiece end so that you can attach a plate that can be customized as a cabling port.
| 22" Dovetail Saddle Plate for the 3600GTO (DOVE3622) 12.9" x 22" (328 x 559mm), 15 lbs. (7kg)
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22" Dovetail Sliding Bar (SB3622)
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Flat Surface Adapter for the 3600GTO (3600FSA)
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We strongly recommend the use of a flat top plate and our 3600 Flat Surface Adapter when designing your setup for the 3600GTO mount, whether on a portable or a permanent pier. The mount’s Pier Adapter Plate is made on a lathe and is machined to very high tolerances; it is as perfectly round as modern CNC machining can produce. The pier component that will receive it should have similar precision. However, most open pipe intended for portable or permanent pier use is neither perfectly round, nor precisely 11.5” in inside diameter. A flat plate machined to fit the pier and drilled for the 3600 Flat Surface adapter is the ideal solution. |
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Bolt circle:
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| 3600FSA | $325.00 | in stock | |
11.5" Counterweight Shaft Extension for the 3600GTO (M3655)
This 2.5" diameter extension is beautifully machined from the same 303 stainless stock as the full counterweight shaft of the 3600GTO and adds another 10" of usable length. The fit of the extension on the primary counterweight shaft is virtually seamless, so your weights will slide up and down smoothly. The large machined counterweight safety stop knob threads into the end to protect your toes. The shaft weighs 13.5 lbs. (6.1kg)
| M3655 | $160.00 | in stock | |
Current Installations
The first two mounts have been in service since the Fall of 2007. Additional mounts were shipped in late 2008 and early 2009. We will post photos as they become available.
Antarctica
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The very first 3600GTO was installed at Dome C at Concordia Station in Antarctica in the Fall of 2007. It was designed to carry a large telescope that will be used for scientific studies by the Laboratoire Universitaire d'Astrophysique de Nice (LUAN). As you can imagine, the Antarctic is the most severe environment on the planet. Maintainance is extremely difficult due to the extreme low temperatures and dangerous wind conditions that prevent technicians from working outdoors. The mount must be a reliable performer and function flawlessly 24 hours per day for the entire polar night lasting 6 months.. |
Our smaller mounts have proven themselves in these frigid Antarctic conditions
since 2003. We have had a number of 900GTO and 1200GTO mounts running continuously
at Dome C in Antarctica, and they have shown 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 large mounting available.
Here are some links that you may wish to check out:
Collection of photos showing the production of the first 3600GTO and subsequent installation at Dome C in Antarctica.
Video of an Astro-Physics 1200GTO operating at -73 degrees Celsius (-99 degrees Fahrenheit)!!! This video was recorded by Erick Bondoux and posted on the DailyMotion.com website August 23, 2008 (copyright by Erick Bondoux). We have prepared an English translation of Erick's comments for your convenience.
Video provides a tour of the Astro-Physics mounts based at dome C. This 3:50 minute video was was filmed May 30, 2008 by Erick Bondoux and is posted on the DailyMotion.com website. You will need to be a little patient with this video since it was filmed with only a faint light on the horizon and all installations had to be lit. You can also hear wind noise. (copyright by Erick Bondoux)
Video entitled: DC4 - Concordia 2008, The Winterover in Antarctica in Dome C Antarctica. This 3:25 minute video will provide a glimpse into the French and Italian Concordia team members, their living environment and equipment used during their 2008 research session. Very entertaining (musical overlay) and informative.
Blog/Journal by Erick Bondoux, which includes additional videos and observations of research and life in Antartica.
Photos from 2003 installation at Dome C. On the linked page click on Photo
Gallery and then scroll down to Astro-Physics place; click on Turbulence
Monitoring; and click on Summer 2003: First Seeing . . .
Astro-Physics and Laboratoire Universitaire d'Astrophysique de Nice (LUAN)
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The 3600GTO was introduced
to astro-imagers at the Advanced Imaging Conference in San Jose, CA in late
October 2007. As imaging trends lean towards larger scopes requiring sturdier
mounts, we felt this was an excellent venue to introduce the 3600 and get
some initial feedback from the astronomers most likely to use it. Pictures
of this informative event are available
here. The mount was under test in our observatory at Astro-Physics.
Walter Piorkowski, head of our mount department, generously allowed us to
use his large 16 inch f/5 Newtonian-Cassegrain to which we added some additional
stainless steel stock on the mounting plate to reach 250 lbs. We feel that
the mount can handle additional weight quite easily. This second prototype shipped to the Laboratoire Universitaire d'Astrophysique de Nice (LUAN) in Nice, France in early June 2008. It was recently installed in a rolloff observatory on the grounds of the Nice Observatory on Mont Gros overlooking Nice and the Mediterranean. It will be used to test software and large professional imaging telescopes. |
| Click to enlarge |
Support
All Astro-Physics mounts are supported by a dedicated staff 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 in 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.
We have prepared some pertinent support documents relating to this mount and many of our other products on our Technical Support page. You may find the information that you need simply by clicking here.
Price and Delivery Information
With rare exception, the 3600GTO and 3600GTOPE are
not available on the shelf for immediate purchase. We typically maintain notification
lists so that we can notify prospective customers when the mount is available
to order. Please refer to our availability page for more information
on our notification lists. If you are not already on the notification list for
the 3600GTO, you can sign up on our online
notification form. An automatic confirmation e-mail will be sent to you
for your records. Refer to Notification
Update periodically to find out the status our mount and telescope production
runs - what we are making throughout the year.
Introductory Prices:
| 3600GTO | $19,900.00 | Call |
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| 3600GTOPE | $26,700.00 | Call |
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Additional Recommended Accessories
Copyright © 1999-2009, Astro-Physics, Inc. - All Rights Reserved
This page was last modified:
April 13, 2009
Astro-Physics, Inc.
11250 Forest Hills Road, Machesney Park, IL 61115, U.S.A.
Phone: 815-282-1513 Fax: 815-282-9847