NexStar computer with SkyAlign and GPS

    The NexStar computer hand control has a built-in database of more
than 45,000 stars, deep space objects, and solar system objects it can locate for
you. The computer's memory contains the following objects:

  • the entire RNGC (Revised New General Catalog) of 7840 nebulas, galaxies, and star

  • the IC (Index Catalog) of 5386 nebulas, galaxies, and star clusters
  • the Messier Catalog of the 110 best known deep sky objects
  • the Caldwell Catalog of 109 fascinating objects that Messier missed
  • 20 famous asterisms
  • the Abell Catalog of 2712 galaxy clusters
  • 25 selected CCD imaging objects

  • 29,500 selected SAO stars, including variable stars and multiple star systems.

    Also included are the eight major planets out to Pluto, as well as
the Moon, for a total database more than 45,000 stars and objects. It's 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
up to 400 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 casual astrophotography.

    A review in Sky & Telescope magazine commented, "To quantify
the Go To pointing accuracy, I spent several nights slewing to 50 objects selected
from the NexStar's database. About one-third of them ended up dead center in the
field, another third landed within ½° of the center, and the remaining third were
within 1° of the center."

    All of the database and scope operation information is displayed on
a double line, 16-character, red-illuminated 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. When it's not displaying menus or object
information, the display also shows you the constantly updated right ascension and
declination coordinates at which the scope is aimed.

    The Sky & Telescope review said, "After using several NexStar-equipped
telescopes in recent years, I can attest to the quality of the software and hardware
for Celestron's Go To system. The package is reliable and offers quick access to
an excellent array of databases. I especially like Celestron's Tour mode, which
steps a user through an eclectic choice of deep-sky objects, quirky asterisms, and
fine double stars, the latter being a class of objects great for urban observing
that many Go To systems ignore. Using NexStar scopes, I've been introduced to many
fine double stars."

    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 the hand control allows you
to operate the telescope remotely via a personal computer. The Sky & Telescope
review said, "The author tried Windows and Mac programs, including Desktop Universe,
ECU, MegaStar, SkyMap Pro, Starry Night,
and TheSky, and all controlled
the mount without any problems."

    There is also an Autoguider port that can use a CCD autoguider to automatically
control the drive motors during long exposure astrophotography. A 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.

    Built-in programmable permanent periodic error correction allows sharper
astrophotographic images, with fewer guiding corrections needed. Built-in adjustable
backlash compensation permits precise corrections during astrophotography and when
observing visually at high powers.

    The operation of the NexStar with SkyAlign is simplicity itself. Once
you mount the scope on its tripod in the altazimuth mode, turn on the power. The
built-in 16-channel GPS (Global Positioning System) receiver 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 day and time based on the split
second accuracy of the GPS time signals. After the location and time have been quickly
and accurately determined, the scope hand control signals you to point the scope
at any three bright stars (you don't have to point at specific known stars). Using
the scope's hand control, center the stars in the finderscope crosshairs. You can
even point at two stars and a planet of the Moon, if you prefer.

    The NexStar SkyAlign computer system automatically determines
which objects were chosen and generates an internal map of the sky that it uses
to guide its automatic moves to any star or object you select for the rest of the
night. It does it by calculating the angles and distances between the objects you've
chosen and compares them to the known separations between objects. Using this method,
the telescope determines what objects were chosen. The display tells 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 SkyAlign scope will unfold all
the wonders of the Universe for you, your family, and your friends.

    If you're using an optional equatorial wedge to polar align the scope
for long exposure astrophotography, two polar alignment programs in the scope's
computer (one for the Northern hemisphere and one for the Southern hemisphere) make
quick work of accurate alignment on the appropriate celestial pole. SkyAlign
does not work in the equatorial mode.

    Several additional alignment methods are built into the NexStar computer
- auto two-star alignment, manual two-star alignment, solar system alignment for
daytime observing, and a one-star manual alignment - allowing you to choose a level
of computer accuracy in automatically finding objects with which you are comfortable.
With GPS and SkyAlign, setting up and using a computerized telescope is faster
and easier than ever before.

    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.

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