CGEM-800 Computerized 8" GoTo Telescope | Telescope.com: Celestron

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Celestron CGEM-800 Computerized 8" GoTo Cassegrain Telescope

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Celestron 8" Schmidt-Cassegrain Telescope with premium StarBright XLT coatings
Features a 40,000 object computerized database with 400 user-definable objects and expanded information on over 200 objects
New All-star polar alignment uses any bright star for a quick and accurate polar alignment
Calibration, Database Filter Limits, Hibernate, Align Procedures, user-defined slew limits included
Autoguide port and auxiliary ports located on the electronic pier for long exposure astrophotography

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Item # 09121

Mfg Model # 11097

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Celestron's CGEM-800 Computerized 8" Cassegrain Telescope offers stable performance and convenient portability for amateur astronomers. Featuring an 8" Optical tube with StarBright XLT coatings it is the most portable model within the CGEM telescope series weighing only 88 lbs., and its ergonomically designed telescope mount provides stargazers the ease of use and mobility they need. The CGEM-800 Equatorial mount was designed to be ergonomically friendly with large Altitude and Azimuth adjustment knobs for quick and easy polar alignment adjustment. The internal RA and DEC motor wiring provides a clean look and an easy and trouble free set up. The CGEM series has a new innovative Polar alignment procedure called All-Star (patent pending). All-Star allows users to choose any bright star, while the software calculates and assists with polar alignment. Another great feature of the CGEM, sure to please astrophotographers is the Permanent Periodic Error Correction (PEC) which will allow users to train out the worm gears periodic errors, while the mount retains the Periodic Error Correction recordings. For objects near the Meridian (imaginary line passing from North to South), the CGEM will track well past the Meridian for uninterrupted astroimaging through the most ideal part of the sky. The CGEM mount has a robust database with over 40,000 objects, 400 user defined programmable objects and enhanced information on over 200 objects. Celestron's CGEM-800 Computerized 8" Cassegrain Telescope mount is the perfect fit beween the Advanced Series and CGE Series.

Warranty

This product is serviced and supported by its manufacturer according to the terms and conditions included in the packaged product. Orion's limited warranty does not apply. Please contact the manufacturer directly for technical support.

Warning

Please note this product was not designed or intended by the manufacturer for use by a child 12 years of age or younger.

Specs

Best for viewing

Brighter deep sky
Best for imaging

Deep sky
User level

User level

Beginner - Suited for a wide range of uses, Level 1 telescopes are simple to operate and set up. Some initial assembly may be required. Very good optical and mechanical quality. Great for families, young people, and folks who don't want to mess with equipment but just want to take a look. Any of these scopes will show you countless lunar craters, Saturn's rings and a myriad of star clusters and nebulas! Referring to the manual is recommended.

Intermediate - These scopes offer higher performance and more advanced features than Level 1 models. They typically take a bit longer to learn and need some set-up or adjustments. But anyone with the slightest technical bent will have no problem getting familiar with these models. Referring to the manual is recommended.

Advanced - These scopes provide the best performance but may require more skill to master and appreciate. They have exceptionally fine optics and mechanics. Some are easy to use but are but on the large or heavy side. Some are intended for specialized uses. These scopes will appeal to the more technically inclined. Referring to the manual is highly recommended.

Expert - Expert telescopes offer uncompromising optical and mechanical quality for the most demanding amateur astronomer. They may be technically involved or designed for specialized use, such as astrophotography or detailed deep sky observation. They carry a premium price, but are designed to provide the ultimate performance in the field. Referring to the manual is highly recommended.

Advanced
Optical design

Optical design

Reflector telescopes use a pair of large and small mirrors to direct incoming light to the eyepiece. Refractor telescopes refract, or "bend" incoming light to a focus by means of an objective lens. Cassegrain telescopes, such as Maksutov-Cassegrains, "fold" incoming light using two mirrors and a front "corrector" lens.

Schmidt-Cassegrain
Finder scope magnification

6x
Optical diameter

Optical diameter

The optical diameter (also known as aperture), is the size of the telescope's main light collecting lens or mirror, measured in millimeters or inches. As the diameter increases, more light is collected and the resolution increases.

203mm
Finder scope lens diameter

30mm
Focal length

Focal length

The focal ratio of an optical system is the ratio of a telescope's focal length to its aperture. Short focal ratios (f/5, f/4.5) produce wide fields of view and small image scales, while long focal lengths produce narrower fields of views and larger image scales.

2032mm
Focal ratio

Focal ratio

The focal ratio of an optical system is the ratio of a telescope's focal length to its aperture. Short focal ratios (f/5, f/4.5) produce wide fields of view and small image scales, while long focal lengths produce narrower fields of views and larger image scales.

f/10.0
Optics type

Optics type

Newtonian reflectors will have either a spherical shaped mirror, which is less expensive to produce, or a higher quality parabola, which does not result in spherical aberration. Cassegrain telescopes routinely use spheres in addition to other lenses in the optical path to correct for residual spherical aberration. Refractors use a series of lenses to provide a clear image. Designs range from a standard air-spaced doublet (two lenses in a row) to exotic designs such as oil-spaced triplets and 4-element multi group lenses.

Spherical
Eyepieces

Plossl 25.0mm (1.25")
Magnification with included eyepieces

81x
Resolving power

Resolving power

The theoretical resolving power of a telescope can be calculated with the following formula: Resolving power (in arc seconds) = 4.56 divided by aperture of telescope (in inches). In metric units, this is: Resolving power (in arc seconds) = 116 divided by aperture of telescope (in millimeters). Note that the formula is independent of the telescope type or model, and is based only upon the aperture of the telescope. So the larger the telescope's aperture, the more it is capable of resolving. This is important to keep in mind when observing astronomical objects which require high resolution for best viewing, such as planets and double stars. However, it is usually atmospheric seeing conditions (not the telescope) which limits the actual resolving power on a given night; rarely is resolution less than one arc-second possible from even the best viewing locations on Earth.

0.57arc*sec
Lowest useful magnification

Lowest useful magnification

Lowest useful magnification is the power at which the exit pupil becomes 7mm in diameter. Powers below this can still be reached with the telescope to give wider fields of view, but the image no longer becomes brighter at a lower power. This is due to the fact that the exit pupil of the telescope (the beam of light exiting the eyepiece) is now larger than the average person's dark adapted pupil, and no more light can fit into the eye.

29x
Highest useful magnification

Highest useful magnification

The highest practical limit is different from the often used "highest theoretical magnification" specification. The "theoretical" limit generally is 50x the aperture of the scope in inches (2x the aperture in mm). So for example, an 80mm refractor is capable of 160x, and a 10" telescope is theoretically capable of 500x magnification. But after approximately 300x, theory breaks down and real world problems take over. The atmosphere above us is constantly in motion, and it will distort the image seen through the telescope. This effect may not be noticeable at lower powers, but at higher powers the atmosphere will dramatically blur the object, reducing the quality of the image. On a good night (a night where the air above is steady and the stars aren't twinkling), the practical upper limit of a large telescope is 300x, even thought the theoretical limit may be much higher. This doesn't mean the scope will never be able to reach those higher "theoretical" powers - there will be that rare night where the atmosphere is perfectly still and the scope can be pushed past it's practical limit, but those nights will be few and far between.

300x
Highest theoretical magnification

480x
Limiting stellar magnitude

Limiting stellar magnitude

The limiting stellar magnitude is a measure of the faintest star you can see through the telescope.

14.0
Optical quality

Optical quality

"Diffraction Limited" means that the limits of image detail are determined by the physical properties of light, and not by optical defects in the telescope.

Diffraction limited
Finder scope

6x30
Focuser

Internal
Diagonal degrees

1.25" 90° Mirror Star
Secondary mirror obstruction

69mm
Secondary mirror obstruction by diameter

34%
Secondary mirror obstruction by area

11%
Mount type

Equatorial
Astro-imaging capability

Astro-imaging capability

The astro-photographic capability of the telescope is based on the style, stability, and accuracy of the mount and tripod. Telescopes on either very lightweight mounts or non tracking mounts (such as Dobsonians) are capable of only very short exposures such as lunar photographs. If a motor drive is attached to an equatorial mount, even a small lightweight mount is capable of capturing some planetary detail. Larger EQ mounts that utilize very precise tracking and excellent stability are capable of longer exposure deep-sky photography.

Lunar, planetary & long exposure
Dovetail bar system

Dovetail bar system

A universal attachment system for holding the optical tube onto the tripod. A dovetail bar is attached to the tube rings, then it slides onto the mount itself, making for quick assembly and disassembly.

Yes
Computerized compatibility

Computerized compatibility

Some mounts are compatible with a motorized Go-To system for fully automated computer finding of objects in the night sky. Others mounts are compatible with computer finding systems which require the user to manually move the mount to the object's position as indicated by the computer finder.

Go-To included
Alignment procedure

2-Star Align, Quick Align, 1-Star Align, Last Alignment, Solar System Align
Number of objects in database

40,000+
Tracking rates

Sidereal, Solar and Lunar
Motor speeds

5°/sec, 2°/sec, 1°/sec, 64x, 16x, 4x, 1x, .5x
Motor type

DC Servo motors with encoders
Power requirement

12-volt DC - 1.5A (tip positive)
PEC

PEC

Periodic errors are inherent in almost all worm gears due to slight eccentricities and misalignments. PEC (Periodic Error Correction) training function provides a manual correcting method to reduce the amplitude of the worm gear errors. By recording a full cycle of guiding actions, the mount can compensate for drifting in the R.A. sidereal tracking caused by periodic errors. The PEC training function is recommended for advanced users with interest in long-exposure astrophotography only. Standard sidereal tracking is sufficient for all casual visual applications, and PEC training is not required. Also, PEC is typically not used in conjunction with an autoguider.

Yes
GPS

GPS

A GPS module automatically sets the date and exact time and location for the mount, relieving the user from the need to look up coordinates on a map or manually enter perfect time. This can be very beneficial when traveling with the scope as locations can quickly be automatically entered into the hand control.

Sold separately
Backlash compensation

Yes
Setting circles

Electronic, via the hand controller
Polar-axis scope

Sold separately
Counterweights

One 4.8 lb.
Available ports

Available ports

Ports allow the mount to connect to devices such as autoguiders (for long exposure photography without tedious manual guiding), PC's running planetarium software (via the RS-232 port) and GPS receivers (through the Aux port).

RS-232, Aux, autoguider
Tube material

Aluminum
Tripod material

Steel
Tripod leg diameter

2.00 in.
Length of optical tube

17.0 in.
Weight, optical tube

13.0 lbs.
Weight, mount/tripod

58.0 lbs.
Weight, fully assembled

88.0 lbs.
Warranty

Two year

Shipping Info

Orders received by noon Pacific Time for in-stock items ship the same business day. Orders received after noon will ship the next business day. When an item is not in-stock we will ship it as soon as it becomes available. Typically in-stock items will ship first and backordered items will follow as soon as they are available. You have the option in check out to request that your order ship complete, if you'd prefer.

A per-item shipping charge (in addition to the standard shipping and handling charge) applies to this product due to its size and weight. This charge varies based on the shipping method.

Standard Delivery: $110.00
3 Day Delivery: $350.00
2 Day Delivery: $350.00
Next Day Delivery: $445.00

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Since 1975 Orion Telescopes & Binoculars has been offering telescopes for sale direct to customers, with an unswerving commitment to best quality products, value and unmatched customer care. Our 100% satisfaction guarantee says it all.

Orion offers telescopes for every level: Beginner, Intermediate, Advanced, and Expert. From our entry level beginner telescopes for amateur astronomers to our Dobsonian telescopes to our most advanced Cassegrain telescopes and accessories, you can find the best telescope for you. And you'll enjoy discount prices by buying your telescope online, direct from Orion. Not sure how to choose a telescope? Orion's Telescope Buyer's Guide is a great place to start.

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Orion's telescope and astrophotography accessories will enhance your telescope enjoyment without breaking the bank. Expand your viewing experience with accessories ranging from moon filters to power-boosting Barlow lenses to advanced computerized telescope mounts. Capture breathtaking photos with our affordable astrophotography cameras. And when you're stargazing, Orion's telescope cases and covers, observing gear, red LED flashlights, astronomy books and star charts will make your observing sessions more convenient, comfortable and meaningful.

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