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More Information  · Supplied Accessories  · Recommended Accessories  · Related Documents  · Images of Some Features Price $2,599.00 List Price $4,327.95 Supplied Eyepiece Highest Useful Magnification 440x Visual Limiting Magnitude 14.7 Focal Length 2800mm Focal Ratio f/10 Resolution 0.42 arc seconds Aperture 11" Weight 91 lbs. Heaviest Single Component 29 lbs. Warranty 2 years

Now, the 11" C11S-GT (XLT) Advanced go-to is priced to make high resolution big aperture automatic astronomy available to almost everyone. Its light weight optical tube and easily assembled mount make it easy to set up and enjoy – either in your back yard or at a distant dark sky site. Superb optical quality and a very reasonable price make it a scope that virtually any beginning or advanced astronomer can afford and enjoy.

This Telescope’s Optical System . . .

• Schmidt-Cassegrain optical tube: 11" aperture (2800mm focal length f/10). Guaranteed diffraction-limited optical performance. The 11" aperture gathers 21% more light than a 10" telescope and almost twice that of an 8" scope, providing bright images of faint deep space objects. The 11" aperture also provides a very sharp 0.42 arc second resolution, to resolve star clusters and show lunar and planetary features is sharp detail. The 24" long aluminum optical tube weighs only 27.5 lbs., making it easy to transport and assemble in the field. There is a handle on the rear of the tube for easier carrying and positioning of the optical tube.

• Starbright XLT fully multicoated optics: This coatings package includes high reflectivity aluminum mirrors enhanced with titanium dioxide for high reflectivity, plus a unique combination of magnesium fluoride and hafnium dioxide antireflection coatings on both sides of the Schmidt corrector lens. The corrector lens itself is made of high transmission water white float glass instead of conventional soda lime glass (which has 3.5% lower transmission) used in other telescopes. Starbright XLT multicoatings visibly increase the contrast on subtle lunar, planetary, and nebula details when compared with a scope with standard multicoatings. They also give you higher light transmission for brighter deep space images and shorter exposure times during CCD and 35mm photography. Across the total visual/photographic spectrum from 400nm to 750mm, independent laboratory tests show the Starbright XLT coatings are 16% brighter than even the legendary Celestron Starbright multicoatings – long considered to be the industry standard for high light transmission.

• Hand-figured optics: Hand figuring the optical system is a complex optical procedure done on a commercial basis only by Celestron. Four separate optical tests are made on every set of optics, using a double-pass laser autocollimator – an Airy disc inspection, a test for spherical aberration by examining the diffraction images on both sides of focus, a Ronchi grating test, and a knife edge test. A skilled optician evaluates these tests, then fabricates a precision pitch lap and delicately hand polishes the secondary mirror to compensate for any small residual zonal defects and smooth the optical figure. Done a few strokes at a time, and testing constantly to evaluate their effect, this final hand-figuring can take hours. But, when it is finished, the optical performance makes every tedious hour of hand-crafting well worth the effort.

• Finderscope: 9 x 50mm straight-through achromatic design, with a wide 5.8 degree field of view. Focuses by loosening the trim ring behind the objective lens cell, screwing the lens cell in or out to focus, and tightening the trim ring to lock in the correct focus.

• Visual back: Removable 1.25" visual back holds visual accessories such as star diagonal, tele-extender, etc.

• Star diagonal: 1.25" prism type.

• Eyepiece: 1.25" 40mm E-LUX Plössl (70x). The eyepiece field of view is 0.61 degrees, 20% wider than the full moon.

• Software: TheSky Level 1 sky charting CD-ROM, with a database of 10,000 stars and deep space objects.

This Telescope’s Mount . . .

• Heavy duty CG-5A Advanced computerized German equatorial mount: The mount includes dual-axis slewing/tracking motors with positioning encoders on each axis for go-to computer control. Built-in adjustable backlash compensation permits precise corrections during astrophotography and when observing visually at high powers. The maximum slewing speed is a fast 4° per second. The mount has setting circles for manually locating objects by their celestial coordinates alone, should you want to observe the old-fashioned way. The scope is supplied with a car battery cord to operate from the cigarette lighter plug of your car or from a rechargeable 12V battery pack. The 7 amp hour capacity Celestron Power Tank #4512V is recommended and will operate the scope all night long without danger of running out of power.
      Manual slow motion controls in both right ascension and declination are standard equipment. To make a casual polar alignment for visual use quick and easy, there’s a latitude scale and fine adjustment controls in both altitude and azimuth. If serious long exposure astrophotography is in your plans, an optional polar finder is available to increase the accuracy of your alignment. The three sliding counterweights are locked in place with a single hand-tighten thumbscrew each, making it easy to rebalance the scope if you add heavy photographic accessories. The mount is easily capable of handling the scope and any reasonable combination of photographic accessories you might want to use. Snap-on covers keep the motor drives free from dust and debris.

• NexStar computer hand control: The supplied computerized hand control has a built-in database of more than 40,000 stars and objects. These include the complete RNGC, Messier, Caldwell, IC, and Abell catalogs; selected SAO stars; the planets, the Moon, and others. You can also store and edit the right ascension and declination of additional user-defined objects of your own choosing, such as the comet and asteroid coordinates published monthly in Astronomy and Sky & Telescope magazines. The computer control can find any of those objects with at your command, and track them with high accuracy for visual or photographic application. There is enhanced information on over 200 of the most note-worthy objects.
      All of the database and scope operation information is displayed on a double line, 16-character, liquid crystal display on the hand control. There are 19 fiber optic backlit LED buttons to make it easy for you to control the computer without affecting your dark-adapted vision. An RS-232 communication port on the hand control allows you to operate the telescope via a personal computer. A separate port accepts an optional CCD autoguider to automatically control the drive motors during long exposure astrophotography. A high precision pointing subroutine in the computer lets you point accurately at objects that you want to photograph that are too dim to be seen though the scope.
      Several different alignment methods are built into the NexStar computer, allowing you to choose a level of computer accuracy in automatically finding objects with which you are comfortable. Both two and (more accurate) three star computer-guided alignment methods are easily accomplished in only a few short minutes. You can be observing in less than 15 minutes after you first take the scope outdoors.
      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. Adding GPS to the computer is something no competitive scope can do. 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 can then orient the scope with the sky, slew to a pair of guide stars, ask you to confirm that the stars are in the center of the field (and center them if they’re not precisely aligned), and then start finding and tracking over 40,000 objects for you at your command. With the Advanced Series go-to mount and the CN16, orienting the scope in time and space on earth and aligning the scope on the sky becomes almost as easy a task as simply turning the scope on.

• Adjustable height tripod: The tripod has 2" diameter stainless steel legs with a center leg brace for rigidity, with excellent damping characteristics. The center leg brace is drilled to form a convenient accessory tray that holds 1.25" and 2" eyepieces to keep them up out of the dew-soaked grass.

• Dovetail slide bar: An adjustable dovetail slide bar allows the optical tube to be quickly and precisely balanced fore and aft on the mount, 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.

• Two-year warranty: All Celestron go-to telescopes have a two-year warranty, double that of competitive go-to scopes.