NexStar 127SLT 127mm go-to altazimuth Maksutov-Cassegrain

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SLT computer
NexStar Computer Hand Control: The supplied NexStar computer hand control has an illuminated numeric keypad and a two-line 16-character LCD display. It stores in a holder that clips to one of the tripod legs. The telescope can be operated with the ergonomically-designed hand control conveniently docked in its holder. You can also remove the control and its coiled connecting cord from the holder for hand-held use. There is no need to worry about wrapping the cord around the mount as you walk around the scope to observe different parts of the sky. The hand control plugs into the fork arm rather than the drive base, so it always moves with the scope.

    The NexStar computer has a database of 4,033 stars and objects that it can locate and track for you. The database includes the complete Messier and Caldwell catalogs of famous deep space objects; a selection of the brightest and best deep space objects from the Revised New General Catalog (NGC); selected SAO stars, including the best variable stars and multiple star systems; the planets; the Moon; and more. You can also store and edit the right ascension and declination coordinates of 25 objects of your own choosing, such as favorite deep space objects or the comet and asteroid coordinates published monthly in Astronomy and Sky & Telescope magazines.

    With the NexStar's hand control, you can select an object catalog at the touch of a button; automatically slew to any of the 4,033 objects in its memory, including over 600 galaxies, 300 star clusters, and dozens of beautiful binary stars; change the slew speed; view fascinating information about an object, including enhanced information on more than 100 particularly fascinating objects; or simply determine if a desired object is visible in the sky. The computer’s hand control/database software and motor drive software can be flash upgraded via the internet so you will always have the most up-to-date software version available.

SkyAlign Technology: With new patent-pending Celestron SkyAlign technology, you don’t have to know Altair from Zubenelgenubi or know how to read a star chart to line up your telescope on the sky. There is also no need to point the telescope north and level the optical tube or to pay extra for a competitive scope that levels the scope and points it north for you. With SkyAlign, the initial position of the telescope is irrelevant. Trees and buildings can block your view of the north celestial pole and you’ll still be able to properly align the scope on the sky. This makes for fast and very easy alignment of the telescope every time you take it out to observe.

    Simply input the date, time, and your location into the computer hand control. The NexStar computer has a U.S. and international city database that lets you easily set your observing location. It will normally default to your last observing site automatically, but can remember up to ten different favorite observing locations for you to choose from. There is also an auxiliary port in the fork arm in the unlikely event you would want to connect an optional Celestron CN-16 GPS (Global Positioning Satellite) module to input the time, date, and observing location automatically by using signals broadcast from space by a network of orbiting government satellites. The SkyAlign system is so quick and easy to use that the added expense of a GPS system is realistically unnecessary.

    Once you’ve entered the date, time, and location, use the Star Pointer red dot LED finder to align the telescope on any three bright stars, or to two stars and a bright planet or even the Moon. You don’t need to know the names of the stars or the planet. The NexStar computer system will automatically determine which objects were chosen and then generate an internal map of the sky that will let it move automatically to any star or object you select for the rest of the night. It does it by calculating the angles and distances measured between the objects you’ve chosen and then compares them to the known separations between objects. Using this method, the telescope determines what objects were chosen. The display will tell you which three objects you aligned to for confirmation.

    Only two of the alignment objects will actually be used for calculating the model of the sky that the computer uses for locating objects. The third object simply provides a positive identification of the other two. Therefore, at least two of the three alignment objects should be spaced at least 60 degrees apart in the sky if possible, and the third object should not fall in a straight line between the first two alignment stars.

    Since the brightest stars appear first as the sky darkens at dusk, the SkyAlign system is exceptionally easy to set up and use as night comes on. You don’t have to guess which stars are brightest, as only the brightest will be visible in the early evening. The same holds true for observers from a light-polluted suburban site, where only the brightest stars are visible to the unaided eye.

    Once the scope has aligned itself with the sky, it takes only a few keystrokes on the computer hand control to have the scope move automatically to your night’s first observing target and start tracking it so you can observe at your leisure. You can find hundreds of fascinating deep space objects your first night out, even if you have never used a telescope before. No matter what level of experience you start from, your NexStar SLT scope will unfold all the wonders of the Universe for you, your family, and your friends.

    You can click on the link below to download a brief RealPlayer movie showing how quick and easy it is to line up your scope on the sky with SkyAlign. There is also a link to download RealPlayer for free if your PC does not already have the program.

SLT mount
The SLT mount’s single fork arm is made of die cast aluminum. It is rigid and damps vibrations quickly. The optical tube mounts onto the fork arm using a no-tool quick-release dovetail bracket for fast set-up and take-down. This allows you to use the mount with other lightweight optical tubes that have the appropriate dovetail. The offset fork arm places the center of mass of the fork arm/optical tube over the axis of rotation of the mount. This keeps the optical tube properly balanced in all planes, no matter where in the sky it is aimed. Built-in friction clutches in altitude and azimuth keep the optical tube firmly centered on the object you are watching when you change eyepieces. No mechanical locking levers are required.
    The mount includes pre-installed dual DC servo motor drives – one for moving the scope in altitude (up/down) and one for azimuth (right/left). The combined motion of the two motors allows the scope to move smoothly in an arc across the sky, following the seemingly curved path taken by the stars and planets. Built-in electronics let you select the appropriate lunar, solar, or sidereal (star) tracking rate to keep each specific kind of object centered in the field of view so that several people can observe at their leisure without having constantly to adjust the position of the scope. The electronics also give you a choice of nine different slewing and centering speeds for locating objects (4°/sec, 2°/sec, 1°/sec, 0.5°/sec, and 32x/16x/8x/4x/2x the sidereal rates).
    A compartment in the drive base holds eight user-supplied AA batteries for powering the telescope. All power connections to the motors are internal. This eliminates the cord wrap problems you often find with competitive telescopes powered by an external battery pack that connects to the scope through a dangling power cord.
    To conserve battery life when the telescope is being used in the backyard, an optional AC adapter (#2338) is available to operate the scope from an extension cord connected to a normal household 110 VAC electric outlet. The Celestron Power Tank (#4512V) is also a highly recommended optional accessory if you observe away from home a lot. This is a 7 amp-hour capacity multi-purpose rechargeable 12V DC battery that can provide several nights worth of observing from a single charge when you’re in the field away from backyard AC.
    The underside of the mount’s drive base is cone-shaped. It slips into a cone-shaped receptacle on the top of the tripod and is held in place by one large hand-tighten knob in the tripod. Assembly is fast and foolproof. There is no need to fumble with multiple mounting bolts, or try to align mounting bolts in a tripod with holes you can’t see in the base of the mount, as is the case with competitive scopes. The SLT mount’s no-tool assembly is foolproof and takes only a few seconds.
    The preassembled adjustable-height tripod has stainless steel legs to damp vibrations quickly. The center leg brace holds a convenient no-tool quick-release accessory tray to keep your eyepieces and accessories up and out of the dew-soaked grass. The locking knobs for the tripod leg height adjustment face inwards, so they won’t snag your clothing as you move around the tripod in the dark.
SLT software
The telescope comes with a CD-ROM of TheSky Level 1 planetarium and star charting software. This Windows-based program will let explore the Universe on your PC and print out custom star charts of the sky to help you find faint objects that are not in the scope computer’s database. In addition, you also get the NexStar Observer’s List (NSOL) control software. This program lets you connect your SLT scope to your Windows-based laptop or PC (with an optional RS-232 cable). It brings up on your computer screen a list of all the objects it the scope’s database. Simply click on any of the objects in the list and the scope will slew to that object (if it is above the horizon) and start tracking it for you to observe.

You can also add optional NexRemote telescope control software to allow you to more completely control the scope from your personal computer or laptop. NexRemote provides an on-screen image of the computer hand control with full control of all the hand control functions from your computer keyboard. In addition to emulating the NexStar hand control, NexRemote adds powerful new features that let you keep your eyes on the stars instead of the hand control. It provides talking computer speech support using your computer’s built-in speaker; lets you control the objects you want to see and the order in which you see them; lets you create and save custom sky tours; lets you take wireless control of the telescope with optional gamepad support; lets you connect your personal GPS device to the NexRemote; downloads NexRemote updates online to use the latest features; and more. The NexRemote software includes an RS-232 cable to connect the scope to a PC.

You don’t have to know how to read a star chart – or even know which way is North – to find your way around the sky with the Celestron 127SLT 127mm go-to Maksutov-Cassegrain. It has Celestron’s famous SkyAlign easy alignment technology and a StarPointer red dot LED finder to make lining up on the sky a breeze.

    Once aligned, the scope’s computer hand control will find more than 4,000 celestial objects for you and will track them unerringly all night long while you observe. With its pre-assembled adjustable height steel tripod and easy no-tool assembly, the NexStar 127SLT can be up and ready to take you on a tour of the Universe in a matter of minutes.

    The 127mm (5”) aperture Maksutov-Cassegrain folded catadioptric optical system of the NexStar 127SLT provides exceptional high contrast/high resolution solar system images – the phases of Mercury; lunar rilles and craters less than three miles across; Martian polar caps and major dark surface features; cloud belts on Jupiter, with some detail in the belts, plus the shadows of Jupiter's moons on the planet during transits; Cassini's division in Saturn's rings on a regular basis, plus four or five of its moons; Uranus and Neptune visible as very small discs.

    Outside the solar system, the high resolution Celestron 127SLT will show you dozens of globular clusters, emission nebulas, planetary nebulas, and galaxies; all of the Messier objects and many of the brighter NGC objects from a dark sky site (with some internal detail visible in many nebulas, although most galaxies will remain relatively featureless hazy patches).

    The NexStar 127SLT has all the features and optical performance needed to keep a casual backyard astronomer happily observing for years. And it can be used for terrestrial observing, too – birdwatching, scanning the scenery from the home with a view, and more.


This Telescope’s Optical System . . .

  • Maksutov-Cassegrain optical system: Aluminum tube 127mm aperture (1500mm focal length f/11.81) folded lens/mirror catadioptric. The system’s Maksutov corrector lens is fully coated on both sides with antireflection material for high light transmission and good contrast. A no-tool quick release dovetail connects the tube to the mount for fast set-up and take-down.

  • Finderscope: StarPointer non-magnifying variable brightness red dot finder on a quick-release dovetail mounting bracket. The StarPointer is a quick and easy way to point your telescope exactly to the desired object in the sky. There’s no need to worry about the inverted images you see through traditional finders. Just align the red dot seen in the StarPointer with the desired star in the sky and you’re done.

  • Internal focuser: Focuses by moving the primary mirror fore and aft in the optical tube by means of a focusing knob on the rear cell.

  • Star diagonal: 1.25” 90° prism type

  • Two 1.25” eyepieces: The first is a 25mm providing 60x. The eyepiece field of view is 0.83° across, more than one and a half times the diameter of the full Moon for expansive views of the Moon, star clusters, and terrestrial observing. The second is a 9mm providing 197x for close-up views of the Moon and planets, globular star clusters, binary stars and more.

This Telescope’s Mount . . .

  • Fork mount/drive system: Single fork arm altazimuth design with pre-installed internal dual DC servo motor drives. A compartment in the drive base accepts eight user-supplied AA batteries for powering the telescope. Selectable lunar, solar, or sidereal (star) tracking rates, with nine different slewing and centering speeds for locating objects (3°/sec, 2°/sec, 1°/sec, and 64x/32x/16x/8x/4x/2x the sidereal rates).

  • NexStar computer control: The supplied computer hand control has an illuminated numeric keypad and a two-line 16-character LCD display. It has a database of 4,033 stars and objects, including the complete Messier and Caldwell catalogs of famous deep space objects; a selection of the brightest and best deep space objects from the Revised New General Catalog (NGC); selected SAO stars, including the best variable stars and multiple star systems; the planets; the Moon; and more.
    With the built-in SkyAlign technology, lining up your 127SLT on the sky each night takes only minutes. Simply input the date, time, and your location into the computer hand control, then use the StarPointer red dot finder to align the telescope on any three bright stars, or to two stars and a bright planet or the Moon. The NexStar computer will automatically align itself with the sky. Then, it takes only a few keystrokes on the computer hand control to have the scope move automatically to your night’s first observing target and start tracking it so you can observe at your leisure. You can find hundreds of fascinating deep space objects your first night out, even if you have never used a telescope before. No matter what level of experience you start from, your NexStar SLT scope will unfold all the wonders of the Universe for you, your family, and your friends.

  • Supplied software: The scope comes with a CD-ROM of TheSky X – First Light Edition planetarium and star charting software. This program will let explore the Universe on your PC or Macintosh and print out custom star charts of the sky from its 10,000 object database to help you find faint objects that are not in the scope computer’s database. In addition, you also get the NexStar Observer’s List (NSOL) control software. This program lets you connect your SLT scope to your Windows-based laptop or PC (with an optional RS-232 cable). It brings up on your computer screen a list of all the objects it the scope’s database. Simply click on any of the objects in the list and the scope will slew to that object (if it’s above the horizon) and start tracking it for you to observe. >

  • Adjustable height tripod: The preassembled tripod has stainless steel legs to damp vibrations quickly. The center leg brace holds a convenient no-tool quick-release accessory tray to keep your eyepieces and accessories up and out of the dew-soaked grass. The height adjustment lock levers are on the inside of the legs to avoid snagging your clothing on them in the dark.

  • Two-year warranty: All Celestron telescopes have a two-year warranty, double that of competitive scopes.
Highest Useful Magnification:
This is the highest visual power a telescope can achieve before the image becomes too dim for useful observing (generally at about 50x to 60x per inch of telescope aperture). However, this power is very often unreachable due to turbulence in our atmosphere that makes the image too blurry and unstable to see any detail.

On nights of less-than-perfect seeing, medium to low power planetary, binary star, and globular cluster observing (at 25x to 30x per inch of aperture or less) is usually more enjoyable than fruitlessly attempting to push a telescope's magnification to its theoretical limits. Very high powers are generally best reserved for planetary observations and binary star splitting.

Small aperture telescopes can usually use more power per inch of aperture on any given night than larger telescopes, as they look through a smaller column of air and see less of the turbulence in our atmosphere. While some observers use up to 100x per inch of refractor aperture on Mars and Jupiter, the actual number of minutes they spend observing at such powers is small in relation to the number of hours they spend waiting for the atmosphere to stabilize enough for them to use such very high powers.
250x
Visual Limiting Magnitude:
This is the magnitude (or brightness) of the faintest star that can be seen with a telescope. The larger the number, the fainter the star that can be seen. An approximate formula for determining the visual limiting magnitude of a telescope is 7.5 + 5 log aperture (in cm).

This is the formula that we use with all of the telescopes we carry, so that our published specs will be consistent from aperture to aperture, from manufacturer to manufacturer. Some telescope makers may use other unspecified methods to determine the limiting magnitude, so their published figures may differ from ours.

Keep in mind that this formula does not take into account light loss within the scope, seeing conditions, the observer’s age (visual performance decreases as we get older), the telescope’s age (the reflectivity of telescope mirrors decreases as they get older), etc. The limiting magnitudes specified by manufacturers for their telescopes assume very dark skies, trained observers, and excellent atmospheric transparency – and are therefore rarely obtainable under average observing conditions. The photographic limiting magnitude is always greater than the visual (typically by two magnitudes).

13.0
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.

1500mm
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/11.81
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.

0.91 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.
5"
Weight:
The weight of this product.
18 lbs.
Telescope Type:
The optical design of a telescope.  Telescope type is classified by three primary optical designs (refractor, reflector, or catadioptric), by sub-designs of these types, or by the task they perform.
Maksutov-Cassegrain
 
Based on Astronomy magazine’s telescope "report cards", scopes of this size and type generally perform as follows . . .
Terrestrial Observation:
Observing terrestrial objects (nature studies, birding, etc.) is usually possible only with refractor and catadioptric telescopes, and convenient only when the scope is on an altazimuth mount or photo tripod. Most reflectors cannot be used for terrestrial observing. Scopes with apertures under 5" to 6" are generally most useful for terrestrial observing due to atmospheric conditions (heat waves and mirage, dust, haze, etc.) that degrade the image quality in larger scopes. 
Yes
Lunar Observation:
Visual observation of the Moon is possible with any telescope. Larger aperture scopes will provide more detail than smaller scopes, thereby getting a higher score in this category, but may require an eyepiece filter to cut down the greater glare from the Moon's sunlit surface so small details can be seen more easily. Lunar observing is more rewarding when the Moon is waxing or waning as the changing sun angle casts constantly varying shadows to reveal craters and surface features by the hundreds.  
Great
Planetary Observation:
Good
Binary and Star Cluster Observation:
Good
Galaxy and Nebula Observation:
Fair
Photography:
Yes
Terrestrial Photography:
Photographing terrestrial objects (wildlife, scenery, etc.) is usually possible only with refractor and catadioptric telescopes, and convenient only when the scope is on an altazimuth mount or photo tripod. Most reflectors cannot be used for terrestrial photography. Scopes with focal ratios of f/10 and faster and apertures under 5" to 6" are generally the most useful for terrestrial photography due to atmospheric conditions (heat waves and mirage, dust, haze, etc.) that degrade the image quality in larger scopes.
Yes
Lunar Photography:
Photography of the Moon is possible with virtually any telescope, using a 35mm camera, DSLR, or CCD-based webcam (planetary imager). While an equatorial mount with a motor drive is not strictly essential, as the exposure times will be very short, such a mount would be helpful to improve image sharpness, particularly with webcam-type cameras that take a series of exposures over time and stack them together. Reflectors may require a Barlow lens to let the camera reach focus. 
Yes
Planetary Photography:
Yes
Star Cluster / Nebula / Galaxy Photography:
No
Warranty:
2 years
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General Accessories
Drive Motors and Drive Accessories (2)
Power Tank 7 Amp-hour 12V DC rechargeable battery
by Celestron
Quantity:  
$69.95 
2.5 Amp AC adapter for Celestron telescopes
by Celestron
Quantity:  
$24.95 
Visual Accessories
Eyepieces (3)
Omni 6mm 1.25" Plossl
by Celestron
Quantity:  
$29.95 
Omni 12mm 1.25" Plossl
by Celestron
Quantity:  
$29.95 
Omni 40mm 1.25" Plossl
by Celestron
Quantity:  
$49.95 
  • 127mm fully coated Maksutov optics
  • Go-to computerized altazimuth mount with dual-axis DC servo motor drives
  • Pre-assembled adjustable height stainless steel tripod
  • Accessory tray
  • Hand control with 4,000+ star and object database for go-to operation
  • Internal AA battery compartment (batteries not supplied)
  • Battery-powered variable brightness StarPointer red LED non-magnifying finder (battery supplied)
  • Internal moving mirror focuser
  • 1.25” prism-type star diagonal
  • 1.25” 25mm eyepiece (60x)
  • 1.25” 9mm eyepiece (167x)
  • TheSky X CD-ROM star-charting software
  • NSOL software for controlling the scope from a laptop or PC
  • Dust covers.
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Celestron - NexStar 127SLT 127mm go-to altazimuth Maksutov-Cassegrain

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Celestron - NexStar 127SLT 127mm go-to altazimuth Maksutov-CassegrainFull length image of the Celestron NexStar 127SLT on its tripod.
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Our Product #: NS127SLT
Manufacturer Product #: 22097
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The NexStar 127SLT (Star Locating Telescope) is a big, but very affordable, go-to 5” aperture Maksutov-Cassegrain with high contrast/high resolution catadioptric optics that is priced far below competitive 5” Maks . . .





. . . our 34th year