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This Celestron CGE Pro German equatorial mount has:
• 90 pound payload capacity
• +/-9 arc second periodic error or less, better when using periodic error correction
• 5.5°/second slewing
• heavy-duty adjustable height stainless steel tripod
• NexStar go-to computer hand control with 40,000+ object database
• 2-year warranty
The German equatorial mount has long been the favored choice of astronomy buffs and astrophotographers because of its stability and portability. It is more stable because the center of gravity is directly over the center of its base, and more portable because it can be broken down into smaller component parts than a fork-mount telescope for easy storage and transportation.
For astrophotography, the German equatorial mount offers easier balancing; unlimited space at the rear of the telescope tube to mount a long camera equipment train that can’t bump into the drive base, as is the case with many fork-mounted scopes; and whole sky access that many fork-mounted scopes can’t achieve.
Heavy duty mount head: The Celestron CGE Pro is a newly-designed high payload capacity/high precision go-to German equatorial mount that epitomizes all of these German equatorial mount virtues. It was named a Sky & Telescope Hot Product for 2010 for its "unquestionable value when it comes to Go To performance for astrophotographers and observers." The CGE Pro is fabricated of CNC machined aluminum and stainless steel and has a full 90 pound payload capacity. This allows it to carry Celestron SCT optical tubes up to 14” in aperture, with as much as 45 pounds of imaging accessories attached, as well as virtually any other optical tube and accessory payload weighing up to 90 pounds. The mount is capable of operating over a latitude range of 10º to 65º in both northern and southern hemispheres.
The mount’s heavy duty right ascension and declination shafts are precision-machined from 1.57” diameter steel tubing with a stout 0.40" wall thickness. Each shaft is supported by two preloaded 2.68” O.D. tapered roller bearings. There is a four-point right ascension and declination clutch system for no-slip pointing precision.
For observing or imaging objects near the meridian (the imaginary line passing directly overhead from North to South), the CGE Pro is designed to track a full 20° past the meridian for uninterrupted imaging through the most ideal part of the sky.
Mount drive system: The CGE Pro mount head contains 12VDC slewing/tracking motors with integrated optical encoders on each axis for go-to computer control. Steel worm gears and brass worm wheels assure long-term reliability and high accuracy performance. Each precision-made steel worm gear is 0.75" diameter and is preloaded with two 0.87" OD ball bearings to minimize run-out (a source of periodic error). The precision-made 255 tooth brass worm wheel is a full 6” in diameter.
The use of low cog DC Servo motors with integrated optical positioning encoders offers smooth, quiet operation and precision slewing and tracking. The seven slot motor armatures are skewed to minimize cogging for precise jitter-free low speed tracking. The declination worm is spring loaded to minimize backlash for smoother and easier guiding.
Drive accuracy (periodic error) is a very good +/- 9 arc seconds or better. This can be further improved by training the permanent periodic error correction circuit built into the mount’s computer hand control to reduce the periodic error inherent in all telescope worm gear drives.
There are nine motor drive speeds: 0.5x and 1x sidereal for guiding; 4x, 8x, 16x, and 64x for centering; and 0.5°, 2°, and a fast 5.5° per second for slewing. Preset tracking rates include sidereal, solar, and lunar. Equatorial tracking modes are available for both northern and southern hemispheres.
The mount requires 2.5 amp 12 VDC power to operate. The maximum 2.5 amp power draw happens only briefly when accelerating to the high speed slewing mode from a standing start. Normal power draw with a well-balanced payload is generally considerably less than half the maximum draw. The mount comes with a car battery cord to operate from the cigarette lighter plug of your car or from a rechargeable 12VDC battery pack. The 17 amp hour capacity Celestron Power Tank #4517V is recommended and will operate the mount all night long without danger of running out of power.
Specially designed power management electronics deliver constant regulated power to the motor so that it is capable of driving the mount even when your scope not perfectly balanced. This allows the CGE Pro to have the payload capacity of that of much larger (and expensive) mounts without sacrificing smooth tracking motion and pointing accuracy across the entire sky.
Polar alignment: To make a casual no-tool polar alignment for visual use quick and easy, there’s a latitude scale with large ergonomically-friendly altitude and azimuth adjustment knobs. If serious long exposure astrophotography is in your plans, the special All-Star Polar Alignment software described below allows you to choose any bright alignment star for a software-assisted alignment of the mount’s polar axis, even if you can't see the North Star.
Counterweight: The CGE Pro mount comes with one 22 pound counterweight. The counterweight locks in place on the 5 pound steel counterweight shaft with a single hand-tighten knob, making it easy to rebalance your scope in right ascension if you add heavy photographic accessories. If needed, optional counterweights are available to balance very heavy loads.
Heavy duty tripod: The CGE Pro mount’s adjustable height Super HD tripod has 2.75” diameter stainless steel legs. It adjusts over a 38” to 55” height range. The height adjustment leg locks are on the inside of the tripod legs to keep them from snagging on clothing in the dark. The tripod uses a dual leg support for maximum rigidity, with an upper leg brace to provide an outward preload and a lower leg brace providing inward tension. The upper leg brace forms a convenient tray that holds eyepieces and accessories to keep them up out of the dew-soaked grass.
Mounting an optical tube: Optical tubes are installed on the CGE Pro mount using a slot on the mount head that accepts a Celestron CGE-style or Losmandy D-plate dovetail slide bar. This allows the optical tube to be quickly and precisely balanced fore and aft on the mount in declination, eliminating the need for an extra counterweight to balance a camera or other accessories. Setup and takedown times are exceptionally fast, as a single large hand-tighten knob holds the optical tube in place. A second lock knob prevents the tube from sliding off the mount should the hand-tighten knob loosen.
Mount weight: The CGE Pro mount weighs a stout 154 pounds. The equatorial head is the heaviest component, at 75 pounds. The tripod and electronic pier weigh a combined 52 pounds. The supplied counterweight weighs 22 pounds, while the thread-in counterweight shaft weighs 5 pounds. With a deadweight lift of 75 pounds to install the equatorial head on the tripod, it might be prudent to have a second person assist you in assembling your CGE Pro mount.
NexStar computer hand control: The NexStar computer hand control of the CGE Pro mount has a built-in database of more than 40,000 stars, deep space objects, and solar system objects it can locate for you. These include the complete RNGC, Messier, Caldwell, IC, and Abell catalogs; selected SAO stars; the planets, the Moon, and others. The custom database lists of all the most famous deep-sky objects by name and catalog number; the most beautiful double, triple and quadruple stars; variable stars; non-planetary solar system objects; and asterisms. It contains enough fascinating objects to keep you busy observing for the rest of your life.
You can also store and edit the right ascension and declination of 100 objects of your own choosing, such as the comet and asteroid coordinates published monthly in Astronomy and Sky & Telescope magazines. The computer control can quickly find any of those objects at your command, and track them with high accuracy for visual observing or astrophotography.
All of the database and scope operation information is displayed on a double line, 16-character, liquid crystal display on the hand control. This display leads you through the steps necessary to line up the scope on the sky, locate objects, control scope functions like the brightness of the hand control display, and much more. It shows you basic information about the object being viewed (such as the object’s name, catalog designation, type, magnitude, and so forth). In addition to this basic information, there is enhanced information on over 200 of the most note-worthy objects. The display can also show you the right ascension and declination coordinates at which the scope is aimed.
There are 19 fiber optic backlit LED buttons that glow a soft red in the dark to make it easy for you to control the computer without affecting your dark-adapted vision. An RS-232 communication port on hand control allows you to control the mount via a personal computer using the supplied NexRemote telescope control software.
The NexStar hand control software, motor control software, and database updates are all flash upgradeable over the Internet.
An autoguider port, PC port, and auxiliary ports are located on the mount’s electronic pier for long exposure astrophotography. The autoguider port can use a six-pin RJ-12 modular jack ST-4 compatible CCD autoguider to automatically control the drive motors during long exposure astrophotography. An RS-232 communication port on hand control allows you to control the mount via a personal computer using the supplied NexRemote telescope control software.
Alignment on the sky and go-to accuracy: No polar alignment finderscope is available for the CGE Pro mount, nor is any needed. A unique Celestron All-Star Polar Alignment program built into the NexStar hand control helps you do a very precise polar alignment in mere minutes for long exposure astrophotography. It works in both northern and southern hemispheres.
To accurately polar align your scope, first do a reasonably-accurate mechanical alignment of the mount on the celestial pole by eye. To make this initial alignment quick and easy, there’s a latitude scale and fine adjustment controls in both altitude and azimuth. Next, use the mount’s standard two-star alignment method to align your scope on the sky. Select a suitable bright star from the NexStar hand control’s data base and slew your telescope to the star. A star near the meridian and close to the celestial equator will give the most accurate alignment results. Then, press the Align button on the hand control and select Polar Align: Align Mount from the hand control menu. Your telescope will re-slew to the alignment star and ask you to center it in the eyepiece in order to “Sync” on the star. After you sync on the star, your telescope will automatically slew to the position that the star should be at if your mount was accurately polar aligned. Use the mount’s altitude and azimuth adjustment knobs to place the star in the center of the eyepiece and press the Align button. That’s all there is to it! Your CGE Pro mount is now accurately aligned on the celestial pole.
Although the telescope’s tracking may be very good after alignment, pointing accuracy may need to be improved (particularly if you are trying to located small objects on a CCD chip), depending on how close your initial mechanical alignment was on the pole, and by much the mount had to be moved during polar alignment. If that’s the case, you can easily update your telescope’s star alignment in a minute or two if necessary.
Once polar aligned, several different sky alignment methods are built into the NexStar computer to line up the scope on the celestial sphere, allowing you to choose a level of computer accuracy in automatically finding objects with which you are comfortable. These include 2-Star Align, Solar System Align, Last Alignment, Quick Align, and 1-Star Align,
With just a standard hand control alignment, the CGE Pro computer has the ability to center a star in your telescope’s eyepiece or on a CCD chip to within 5 arc minutes. Using the NexStar computer's advanced pointing features (such as Calibration Stars, Sync, and Precise Go-To) further improves the pointing accuracy to as low as 1 arc minute in the desired region of the sky. The high precision pointing subroutine (Precise Go-To) in the computer lets you point accurately at objects that you want to photograph that are too dim to be seen though the scope. Other software features include: database filter limits, a mount hibernate mode, and user-defined slew limits.
GPS compatible: In addition, the NexStar computer hand control is GPS-compatible (using an optional inexpensive CN16 GPS module) for full GPS (Global Positioning System) satellite accuracy. Once the scope is approximately polar aligned, the 16-channel CN16 GPS system uses signals from government satellites to calculate the scope’s location on earth with an accuracy measured in meters. The system also calculates the current time based on the split second accuracy of the GPS time signals. After the CN16 quickly completes these calculations and enters the information into the computer control for you automatically, the computer then orients the scope with the sky, slews to a pair of guide stars, asks you to confirm that the stars are in the center of the field (and center them if they’re not precisely aligned), and then starts finding and tracking over 40,000 objects for you at your command. With the CGE Pro go-to mount and the CN16, orienting the scope in time and space on earth and aligning your telescope on the sky becomes almost as easy a task as simply turning on your CGE Pro mount.