11" f/2.2 Rowe-Ackermann Schmidt Astrograph (RASA) on CGE Pro Mount

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This Celestron 11” f/2.2 Rowe-Ackermann Schmidt Astrograph (RASA) CGE Pro mount combination has: 

Very fast 11" f/2.2 Rowe-Ackermann Schmidt optics 
StarBright XLT optical multicoatings for the highest possible light transmission 
MagLev DC cooling fan and cooling vents 
Built-in four-element rare earth corrector lens 
42mm T-thread and 48mm camera adapters 
CGE Pro go-to German equatorial mount 
2-year warranty

Details on the Celestron 11” RASA optical tube . . .
 
The Celestron Rowe-Ackermann Schmidt Astrograph (RASA) updates and improves the Celestron Schmidt camera, a premium wide-field imaging instrument of the 1970s that had a loyal following, but a difficult instrument to use that only a really hard-core 35mm film astrophotographer could love.
 
Today, fast DSLR and CCD electronic imaging has taken the place of slow 35mm film. Home computers can manipulate and improve DSLR and CCD images in ways that 35mm imagers could only dream of. DSLRs and CCD cameras can have sensors as large as (and in some cases larger than) 35mm film. 

To compensate for these new large sensors Celestron had to push the boundaries of the Schmidt camera design and make an entirely new type of instrument, the RASA. The Celestron RASA provides an advance in the performance of deep space imaging scopes that lets today’s amateur astrophotographers produce wide field results rivaling those of the best professional observatory photos of only a few short years ago.
 
The 11” 620mm focal length f/2.22 Celestron Rowe-Ackermann Schmidt Astrograph is an imaging-only optical tube. It has a huge 70mm image circle that can handle full frame DSLRs and the largest sensor size CCD cameras with minimal or no vignetting. The RASA combines a proven Schmidt corrector optical system with a built-in 4-element rare earth corrector lens that keeps the images free of coma, field curvature, and false color. The optical quality and spot size across the entire image circle are unprecedented for an astrograph in this price range – or even that of much more expensive instruments. 

Its fast, wide field, f/2.22 optics give you two huge advantages over traditional f/10 catadioptric imaging scopes (even those using an optional f/6.3 or f/7 focal reducer). You get better apparent tracking due to the image scale, plus shorter exposure times due to the speed of the optics. That means you can create better-looking deep space images and mosaics in a fraction of the time it used to take, even without using an autoguider.
 
The Celestron 11" RASA has a Rayleigh Limit (photographic resolution) of 0.50 arc seconds. It is capable of revealing much finer deep space detail than a similar focal length 4" apo refractor (a scope type often used for wide field imaging), which has a Rayleigh Limit of 1.36 arc seconds. And the RASA will record those more detailed images in a fraction the time of that 4" apo. 

The Celestron 11” RASA optical tube includes a custom-engineered linear brass focuser bearing to reduce image shift It is combined with a FeatherTouch Micro Focus Knob to allow you to make the precise fine adjustments you need to capture the perfect image. Mirror locks hold your precise focus. A quiet high-output 12V internal MagLev fan on the rear cell reduces cooldown time and provides optimal airflow through the dust filtered 33” long optical tube.
 
Naturally, industry leading StarBright XLT optical multicoatings are standard for the highest possible light throughput. 42mm T-thread DSLR and 48mm CCD camera adapters are standard equipment. Two Losmandy-style “D-plate” dovetails are standard, one on the bottom of the RASA for installing it on the CGE Pro mount, and one on top for installing accessories (such as on optional photoguide scope). The back focus from the included camera adapters is 55mm.
 
Naturally, an astrograph as good as the Celestron 11" RASA demands an equally good mount. The Celestron CGE Pro is that mount.
 
Details on the Celestron CGE Pro go-to German equatorial mount . . .
 
Heavy duty CGE Pro computerized German equatorial mount: The CGE Pro mount includes dual-axis slewing/tracking motors on each axis for go-to computer control. 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.

The inherent drive accuracy (periodic error) of the observatory-grade CGE Pro mount is a very good +/- 9 arc seconds or better, which can be further reduced by using the scope’s permanent periodic error correction program.
 
Powering the CGE Pro: 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 optional 17 amp hour capacity Celestron Power Tank #4517V is recommended and will operate the scope all night long without danger of running out of power.
 
Polar alignment: To make a casual polar alignment quick and easy, there’s a latitude scale with large ergonomically-friendly altitude and azimuth adjustment knobs. 

No polar alignment finderscope is available to aid in the precise polar alignment required for long exposure astrophotography, nor is any needed. A unique Celestron All-Star Polar Alignment program built into the NexStar hand control helps you do a very precise computerized polar alignment in mere minutes, using any bright star, even when Polaris is hidden by trees or buildings. The program works in both northern and southern hemispheres.
 
Adjustable height tripod: The 52 pound tripod and electronics pier has 3” diameter stainless steel legs with dual leg braces for rigidity and excellent vibration damping characteristics. The top brace forms a convenient tray that holds eyepieces and accessories to keep them up out of the dew-soaked grass.
 
Mounting the scope: A dovetail slot on the top of the 75 pound mount head holds the long Losmandy-style "D-plate" dovetail slide bar mounted under the optical tube. This allows you to slide the optical tube fore and aft in the dovetail slot to quickly and precisely balance the optical tube in declination when you add or subtract accessories, eliminating the need for an extra counterweight to balance your camera or other accessories. 

Three large hand-tighten knobs in the oversized dovetail mounting platform hold the optical tube very securely in place. With a dead weight lift of 75 pounds to install the equatorial head onto the tripod, it might be prudent to have a second person assist you when assembling your CGE Pro mount. 

Balancing the scope: The single sliding 22 pound counterweight is locked in place on the removable 5 pound counterweight shaft with a single large hand-tighten knob each. This makes it easy to rebalance the scope in right ascension if you add heavy photographic accessories.
 
NexStar computer hand control: The supplied NexStar computer hand control has a built-in database of more than 40,000 stars and objects that it can find and track for you. An RS-232 communication port on the hand control allows you to operate the telescope via a personal computer using the supplied RS-232 cable and NexRemote software CD-ROM. 

The hand control and motor control software is flash-upgradeable to allow you to download the latest product updates over the Internet to keep your CGE Pro mount always at the cutting edge of technology. An autoguider port is located on the electronic pier for guided, but unattended, long exposure astrophotography.
 
The NexStar display: 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. The NexStar hand control provides an easily-visible illuminated right ascension and declination readout of the scope’s position on the sky. 

Aligning on the sky: Five different alignment methods are built into the NexStar computer – 2-star align, quick align, 1-star align, last alignment, and solar system align – allowing you to choose a level of computer accuracy in automatically finding objects with which you are comfortable. Alignment is easily accomplished in only a few short minutes. You can start imaging in less than 15 minutes after you first take the scope outdoors, although cooldown of the 11” optics may take a little longer (even with the cooling vents). 
The unique "All-Star” software-assisted alignment of the mount’s polar axis using a single bright star can have you ready for imaging before it’s even dark enough to see the North Star. 
 
NexRemote Software: The supplied NexRemote telescope control software allows you to control your CGE Pro mount from your personal computer or laptop. NexRemote provides full emulation of every aspect of the Celestron computerized hand control including: alignment in any tracking mode; go to any database object; setup of user objects; hibernation; connection to popular planetarium programs; etc.
 
The NexRemote software adds powerful new features that let you keep your eyes on the stars instead of the computer screen. It enables talking computer speech support using your computer’s built-in speaker; controls the objects you want to see and the order that you see them; creates and saves custom tours by launching NexTour; connects your personal GPS device to NexRemote using NexGPS; and more. You can download NexRemote updates online to use the latest features. The NexRemote software includes an RS-232 cable to connect your CGE Pro mount to a PC.
 
Two-year warranty: All Celestron go-to telescopes have a two-year warranty, double that of competitive go-to scopes. 

The complete RASA/CGE Pro mount combination weighs 189 pounds (85.9 kg). The tripod/electronics pier is the heaviest component, at 52 pounds (23.6 kg). The equatorial head weighs 75 pounds (34.1 kg). The supplied counterweight weighs 22 pounds (10 kg) each, and the counterweight shaft 5 pounds (2.3 kg). The 11” RASA optical tube weighs 35 pounds (15.9 kg). The image shown above includes an optional CCD camera mounted on the RASA OTA.

Focal Length:
This is the length of the effective optical path of a telescopeor eyepiece (the distance from the main mirror or lens where the lightis gathered to the point where the prime focus image is formed). Focallength is typically expressed in millimeters.

The longer the focallength, the higher the magnification and the narrower the field of viewwith any given eyepiece. The shorter the focal length, the lower themagnification and the wider the field of view with the same eyepiece.

620mm
Focal Ratio:
This is the ‘speed’ of a telescope’s optics, found by dividing the focal length by the aperture. The smaller the f/number, the lower the magnification, the wider the field, and the brighter the image with any given eyepiece or camera.

Fast f/4 to f/5 focal ratios are generally best for lower power wide field observing and deep space photography. Slow f/11 to f/15 focal ratios are usually better suited to higher power lunar, planetary, and binary star observing and high power photography. Medium f/6 to f/10 focal ratios work well with either.

An f/5 system can photograph a nebula or other faint extended deep space object in one-fourth the time of an f/10 system, but the image will be only one-half as large. Point sources, such as stars, are recorded based on the aperture, however, rather than the focal ratio – so that the larger the aperture, the fainter the star you can see or photograph, no matter what the focal ratio.

f/2.2
Resolution:
This is the ability of a telescope to separate closely-spaced binary stars into two distinct objects, measured in seconds of arc. One arc second equals 1/3600th of a degree and is about the width of a 25-cent coin at a distance of three miles! In essence, resolution is a measure of how much detail a telescope can reveal. The resolution values on our website are derived using the Dawes’ limit formula.

Dawes’ limit only applies to point sources of light (stars). Smaller separations can be resolved in extended objects, such as the planets. For example, Cassini’s Division in the rings of Saturn (0.5 arc seconds across), was discovered using a 2.5” telescope – which has a Dawes’ limit of 1.8 arc seconds!

The ability of a telescope to resolve to Dawes’ limit is usually much more affected by seeing conditions, by the difference in brightness between the binary star components, and by the observer’s visual acuity, than it is by the optical quality of the telescope.

0.50 arc seconds
Aperture:
This is the diameter of the light-gathering main mirror or objective lens of a telescope. In general, the larger the aperture, the better the resolution and the fainter the objects you can see.
11"
Weight:
The weight of this product.
189 lbs.
Heaviest Single Component:
The weight of the heaviest component in this package.
75 lbs.
Warranty:
2 years
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11" f/2.2 Rowe-Ackermann Schmidt Astrograph (RASA) on CGE Pro Mount

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11" f/2.2 Rowe-Ackermann Schmidt Astrograph (RASA) on CGE Pro MountClose-up of the 11" RASA rear cell, showing the focuser, mirror locks, cooling fan, and one of the cooling ventsGraph of the field illumination of the 11" Celestron RASA, showing the minimal falloff.Graph of the ray trace of the complete 11" Celestron RASA optical system.Graph showing the image circle of the 11" Celestron RASA, relative to the chip size of various cameras.Graph of the spot matrix of the 11" Celestron RASA optical tube.11" Celestron RASA image of Markarian's Galaxy Chain (a 900x900 pixel portion of the 2136x1752 pixel original.A closer 11" Celestron RASA image of Markarian's Galaxy Chain (a 900x900 pixel portion of the 2136x1752 pixel original.11" Celestron RASA image by John Davis of the Propeller Nebula (a 900x900 pixel portion of the 1600x1153 pixel original.
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Our Product #: CRA-PRO
Manufacturer Product #: 11101
Price: $7,999.00  FREE ground shipping - Click for more info
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Combine the exceptional wide-field imaging optics of the Celestron 11" f/2.22Rowe-Ackermann Schmidt Astrograph (RASA) with the proven excellence of the heavy-duty Celestron CGE Pro go-to equatorial mount and you have an imaging scope that isequally at home in your backyard, in your observatory, or in the field at a darksky site.





. . . our 37th year