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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 Mach2GTO, 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.
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:
Extremely solid, rugged, high payload mount, yet the equatorial head comes apart into two components for hassle-free field setup.
Operate with 12V battery.
You can take it to the darkest skies and power it with a commonly available 12V battery. In the observatory, we suggest a minimum 5 amp filtered, regulated power supply like our 13.8V, 5-amp Power Supply (PS13V5A). For a heavy payload in cold conditions, we offer a 15V, 10-amp power supply (PS15V10AC).
Allow manual operation if power is not available. One of the truly unique features of the 1600GTO is the ability to use the clutches to help you balance your setup, then you can bolt the R.A. and Dec. axes in place so that they do not move for clutchless operation.
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. This feature of our GTO mounts has been a real customer favorite.
Easy alignment for non-critical viewing.
You can align the 1600GTO using setup routines in the keypad, or with a polar alignment scope to quickly zero in on the pole for most non-critical observing or to get close before tweaking in for imaging (polar scope not included). You can even align the mount during the day with our clever Daytime Polar Alignment Routine (outlined in the Keypad Manual) for solar observing, viewing the planets at twilight, or just getting a jump start on a long night.
Multiple Options for Controlling your Mount in the Field or Your Observatory
You have your choice of the GTO Keypad (optional), which is a full-featured handheld computer, PC computers using a wide variety of software with or without our ASCOM driver, Mac computers or even your mobile smart device (like your iPhone or iPad).
Precise Mechanical Fabrication
Using modern CNC machining techniques, we make all components to a high precision level, which 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. Massive thrust bearings and preloaded shaft bearings provide excellent stability under all imaging situations.
Easy to Adjust and Maintain
The design of the 1600GTO is straightforward with modular construction and no complicated internal wiring. We provide information in the Technical Support section of our website pertaining to typical adjustment issues.
Components are modular
All electronics including the GTOCP4 control box, motors, gearbox or cables can be removed for servicing. The RA and Dec axes can be shipped separately, if needed.
||All CNC machined aluminum bar stock, stainless steel, brass; stainless steel fasteners
|Finishing and Assembly
||Every part is hand-finished and inspected. All assembly is done by hand, by highly skilled mount assembly staff.
|Worm wheel - R.A. & Dec.
||10.3" (262 mm), 225 tooth aluminum
|Worm gear - R.A. & Dec.
||1.22" (31 mm) diameter special low-wear alloy
|Axis shaft - R.A. & Dec.
||3.74" (95 mm) diameter
|Shaft axis bearings - R.A. & Dec.
||5.71" (145 mm) diameter
||0 to 78 degrees
||Approximately 13 degrees (+/- 6.5 degrees from center)
||1.875" (47.6 mm) diameter x 19.5" (495 mm) long [18.5" (470 mm) useable length], incl. large machined safety stop knob. Optional 9" (229 mm) shaft extension available.
|Weight of mount
Total: 114.0 lb. (51.8 kg)
R.A. axis/polar fork: 58.5 lb. (26.6 kg)
Dec. axis: 38.5 lb. (17.5 kg)
Dec. top plate 3.0 lb. (1.4 kg)
Counterweight shaft: 14 lb. (6.4 kg)
||Approximately 220 lb. (100 kg) scope and accessories (not including counterweights), depending on length. Recommended for refractors up to 250 mm, 18-20" Cassegrains, Ritchey-Chretiens and CDKs.
These are only guidelines. Some telescopes are very long for their weight or heavy for their size and will require a larger mount. Remember also that imaging requirements are more rigid than visual observation. Maximum capacity may require the use of the 9" extension (M12675)
|Instrument mounting interface
||Refer to list of suitable mounting plates below
|Pier adapter base diameter
9.775" (248.3 mm) Base. The base is an integral part of the mount and azimuth adjuster.
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 the1100GTO and Mach2GTO (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.
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.
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.
GTOCP4 Servo Drive System Specifications
||Rated for industrial and automotive applications
||High-torque, zero-cogging Swiss DC servo motors, enclosed in machined aluminum housing
||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
||~ 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
||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
Absolute Encoders - 1100GTO-AE and 1100GTO-AEL
The 1100GTO mount has been designed and engineered to accomodate extremely precise Absolute Encoders. These are the same encoders as are used on the 1600GTO.
Absolute Encoders allow the mount to know its exact location regardless of accidental software errors and will allow its recovery. This is particularly important in remote setups. Furthermore, they virtually eliminate periodic error, reducing it below 0.2 arcseconds in our tests. If you order the 1100GTO-AE or 1100GTO-AEL, the R.A. and Dec. encoders will be installed and fully tested with the mount prior to shipment.
However, if you purchase the 1100GTO without encoders, you may purchase the Absolute Encoder Kit at some point in the future and install them yourself. This do-it-yourself upgrade option will not be available until the latter half 2016.
Check out the 10 minute (600 seconds) unguided exposure by clicking on the thumbnail. Note that this image was taken with the 1600GTO, but as mentioned earlier, the same encoders are used on the 1100GTO, so the performance is representative.
Flexible Control with Your Keypad, Computer or even your Mobile Smart Device!
PEMPro Software, Version 2
PEMPro (Periodic Error Management Professional), Version 2, by Sirius Imaging is included with this mount. It is a very powerful Windows software application that allows you to correct your mount's periodic error, polar alignment and backlash using your CCD Camera or Webcam to dramatically improve tracking and guiding. As mentioned previously, our extensive testing procedures include several PEMPro runs so that your new mount will perform with optimum PE correction out of the box. Simply use the Keypad or the PulseGuide software to turn PE Correction "on." Although you will not need to use PEMPro when you receive your mount, you may wish to do a PEMPro run at a later date after the worm gear has run in. Depending on usage, re-measuring error and re-loading periodic error correction from one to four times a year is a good practice, especially if you do some unguided images from time to time. PEMPro also includes a powerful polar alignment routine.
Pier Mounting Options
The 1600GTO mount integrates a precision rotating pier adapter and azimuth adjuster as part of its base. The mount's base will directly attach to the Astro-Physics pier, or it can be attached to any flat surface using the Flat Surface Adapter for 1600GTO and all 1200 Mounts (1612FSA). When choosing the Advanced Telescope System's (ATS) Pier, you will need to order our Flat Surface Adapter with Flat Pier Plate 1612FSA-FP that will fit into the top of their pier. The 1600GTO's large adjustable 0 to 78 degree latitude range (which spans from Antarctica to the arctic circle) makes the use of a wedge unnecesary.
To determine the appropriate pier height for your system and to calculate many of the dimensions that vary with your latitude setting, please try this Excel spreadsheet Latitude Dimension Calculator.
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-ug and ap-gto user groups in the Yahoogroups forum. The user groups are comprised of scope and 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
Shipping charges: $250 for ground shipment within the 48 continguous states; contact us for other destinations.
On October 16, 2015, we introduced a change in the pricing structure for our mounts:
* The Keypad is now optional and will remain so.
* Shipping charges are now shown separately, rather than included in the price of the mount.
1600GTO - 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
Items that You will Need for Your Mount
* Counterweight: Stainless Steel Counterweights - 5, 10, 18, 24 lb.
* Saddle Plate: DOVELM162, DOVELM2, DOVEPW, 1200RP, FP1800, DOVE15
* D-Style (3") Dovetail Plate: Check out our wide selection of D-Style Dovetail Plates, 13" and 16" Side-by-Side Plates (SBD13SS and SBD16SS) and Vixen Dovetail Converter (SBD2V)
* P-Style (7.65") Dovetail Plate: 23" PlaneWave Style Dovetail Plate (SBPW23)
* Pier: Astro-Physics Portable Pier - 10" diameter, heights 24",32",42",48",54",62", Advanced Telescope Systems (ATS) Portable Pier or build your own permanent pier
* Regulated Power Supply: 13.8-volt, 5-amp (PS138V5A) or 15-volt, 12-amp (PS15V12AC) Regulated Power Supply with Cigarette Adapter
* Portable Rechargeable 12-volt Battery Pack: Several sizes and types are available from a variety of vendors. Be sure that your battery pack can supply adequate power for an entire observing session! We recommend having separate batteries - one for the mount and another for all other accessories: camera, dew removers, etc. We do not offer any battery packs at this time.
Additional Accessories to Consider
* GTO Keypad with 15' Coiled Cable and Keypad Protector (KEYVFK)
* Astro-Physics Command Center (APCC) software
* Absolute Encoders
* Right-Angle Polar Alignment Scope with LED Illuminator - 1600GTO, 1100GTO, Mach2GTO and all 900 and 1200 Mounts (RAPAS)
* Losmandy Polar Alignment Scope with LED Cable for 1100GTO and 1600GTO (PASILL4L-179)
* Losmandy Polar Alignment Scope Adapter for 1100GTO and 1600GTO (Q16030)
* 9" Counterweight Shaft Extension (M12675)
* Flat Surface Adapter (1612FSA)
* Flat Surface Adapter with Flat Pier Plate for 1600GTO and all 1200 Mounts - For 10" ATS and other non-Astro-Physics piers (1612FSA-FP)
* Pier Accessory Trays and Support Bar