3600GTO German Equatorial Mount (3600GTO)
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 FeaturesImage past the meridian
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.
|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
Integrated Pier Adapter
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.
Precise Mechanical Fabrication
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.|
|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. Please refer to the GTOCP3 Control Box and Keypad for Servo Drive section on our website for more detailed information on the servo drive system.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 ComputerKeypad Operation
Please 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.
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.
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.
Optional 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.
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.
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 the Availability page on our website 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 the Notification Update section of our website periodically to find out the status our mount and telescope production runs - what we are making throughout the year.
11250 Forest Hills Road, Machesney Park, IL 61115, U.S.A.
Phone: 815-282-1513 Fax: 815-282-9847