Celestron NEXSTAR 4 User manual

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IN NS ST TR RU UC CT TI IO ON NM MA AN NU UA AL L

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INTRODUCTION ........................................................................................................................................ 4
WARNING ................................................................................................................................................... 4
ASSEMBLY .................................................................................................................................................. 8
ASSEMBLING THE NEXSTAR ....................................................................................................................... 8
Powering the NexStar ............................................................................................................................ 8
The Hand Control.................................................................................................................................. 9
The Eyepiece.......................................................................................................................................... 9
The Star Pointer Finderscope.............................................................................................................. 10
HAND CONTROL ..................................................................................................................................... 12
HAND CONTROL OPERATION .................................................................................................................... 13
Alignment Procedure ........................................................................................................................... 13
Auto-Align............................................................................................................................................ 13
Two Star Alignment ............................................................................................................................. 15
Quick-Align.......................................................................................................................................... 15
NexStar Re-Alignment ......................................................................................................................... 16
OBJECT CATALOG..................................................................................................................................... 16
Selecting an Object .............................................................................................................................. 16
Slewing to an Object............................................................................................................................ 16
Tour Mode ........................................................................................................................................... 17
DIRECTION BUTTONS................................................................................................................................17
Rate Button .......................................................................................................................................... 17
SETUP PROCEDURES ................................................................................................................................. 18
Tracking Mode ................................................................................................................................................. 18
Tracking Rate ................................................................................................................................................... 18
View Time-Site ................................................................................................................................................ 18
Sidereal Time ................................................................................................................................................... 18
Filter Limits...................................................................................................................................................... 18
Date/Time ............................................................................................................................................ 19
User Defined Objects ....................................................................................................................................... 19
Get RA/DEC ........................................................................................................................................ 19
Get Alt-Az ............................................................................................................................................ 19
Goto R.A/Dec....................................................................................................................................... 19
Goto Alt-Az .......................................................................................................................................... 19
UTILITY FEATURES ................................................................................................................................... 20
Steup Time-Site................................................................................................................................................ 20
Anti-backlash ................................................................................................................................................... 20
Slew Limits ...................................................................................................................................................... 20
Direction Buttons ............................................................................................................................................. 20
Light Control.................................................................................................................................................... 20
Select Model..................................................................................................................................................... 20
RS-232.............................................................................................................................................................. 20
Hand Control Command Tree ............................................................................................................. 21
TELESCOPE BASICS............................................................................................................................... 22
IMAGE ORIENTATION................................................................................................................................22
FOCUSING ................................................................................................................................................. 23
CALCULATING MAGNIFICATION ............................................................................................................... 23
DETERMINING FIELD OF VIEW .................................................................................................................. 23
GENERAL OBSERVING HINTS .................................................................................................................... 24
ASTRONOMY BASICS ................................................................................................................................25
THE CELESTIAL COORDINATE SYSTEM..................................................................................................... 25

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MOTION OF THE STARS ............................................................................................................................. 26
POLAR ALIGNMENT (WITH OPTIONAL WEDGE)......................................................................................... 27
Photography with the NexStar 4.......................................................................................................... 28
Finding the North Celestial Pole ......................................................................................................... 28
CELESTIAL OBSERVING ...................................................................................................................... 30
OBSERVING THE MOON............................................................................................................................. 30
OBSERVING THE PLANETS......................................................................................................................... 30
OBSERVING THE SUN ................................................................................................................................31
OBSERVING DEEP SKY OBJECTS ............................................................................................................... 31
SEEING CONDITIONS ................................................................................................................................. 31
Transparency ....................................................................................................................................... 31
Sky Illumination................................................................................................................................... 31
Seeing................................................................................................................................................... 32
TELESCOPE MAINTENANCE............................................................................................................... 33
CARE AND CLEANING OF THE OPTICS ....................................................................................................... 33
OPTIONAL ACCESSORIES .................................................................................................................. 34
APPENDIX A - TECHNICAL SPECIFICATIONS ............................................................................... 37
APPENDIX B - GLOSSARY OF TERMS............................................................................................... 38
APPENDIX C – MAPS OF TIME ZONES.............................................................................................. 41
SKY MAPS ................................................................................................................................................. 43

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Congratulations on your purchase of the Celestron NexStar! The NexStar ushers in a whole new generation of computer
automated technology. Simple and friendly to use, the NexStar is up and running after locating just two alignment stars.
It’s the perfect combination of power and portability. If you are new to astronomy, you may wish to start off by using the
NexStar's built-in Sky Tour feature, which commands the NexStar to find the most interesting objects in the sky and
automatically slews to each one. Or if you are an experienced amateur, you will appreciate the comprehensive database of
over 4,000 objects, including customized lists of all the best deep-sky objects, bright double stars and variable stars. No
matter at what level you are starting out, the NexStar will unfold for you and your friends all the wonders of the Universe.
Some of the many standard features of the NexStar include:
• Incredible 4°/second slew speed.
• Fully enclosed motors and optical encoders for position location.
• Integrated hand controller – built into the side of the fork arm.
• Storage for programmable user defined objects; and
Many other high performance features!
The NexStar’s deluxe features combined with Celestron’s legendary optical standards give amateur astronomers one of the
most sophisticated and easy to use telescopes available on the market today.
Take time to read through this manual before embarking on your journey through the Universe. It may take a few observing
sessions to become familiar with your NexStar, so you should keep this manual handy until you have fully mastered your
telescope’s operation. The NexStar hand control has built-in instructions to guide you through all the alignment procedures
needed to have the telescope up and running in minutes. Use this manual in conjunction with the on-screen instructions
provided by the hand control. The manual gives detailed information regarding each step as well as needed reference
material and helpful hints guaranteed to make your observing experience as simple and pleasurable as possible.
Your NexStar telescope is designed to give you years of fun and rewarding observations. However, there are a few things to
consider before using your telescope that will ensure your safety and protect your equipment.
Warning
 Neverlookdirectlyatthesunwiththenakedeyeorwithatelescope(unlessyouareusingthepropersolar
filter). Permanent and irreversible eye damage may result.
 Never use your telescope to project an image of the sun onto any surface. Internal heat build-up can damage the
telescope and any accessories attached to it.
 Never use an eyepiece solar filter or a Herschel wedge. Internal heat build-up inside the telescope can cause these
devices to crack or break, allowing unfiltered sunlight to pass through to the eye.
 Never leave the telescope unsupervised, either when children are present or adults who may not be familiar with the
correct operating procedures of your telescope.

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Focuser Knob
StarPointerEyepiece
Flip Mirror
Attach the included accessories (eyepiece and Star
Pointer finderscope) and remove the front lens
cover. Remove plastic cover over the battery and
turn-on the Star Pointer by rotating the dial on the
side. (For instructions on aligning the Star Pointer
see the Assembly section of the manual).
Rotate the tube so it is level with the ground. Lift
the battery compartment cover to install batteries.
PowertheNexStarusingtheswitchnexttothe12v
outlet at the base of the fork arm.
Remove the NexStar from its packaging and place
the base on a sturdy, level surface. Remove the
accessories from their individual boxes.
The first time the NexStar is powered on the display will
read Select Model. Use the Up and Down scroll buttons to
select your NexStar model from the list and press ENTER.
When the display reads NexStar Ready, press ENTER to
AutoAlign the NexStar. The hand control display will ask
you to move the telescope tube so that it is level with the
ground and facing the north horizon. Use the direction
arrow buttons on the hand control to position the telescope
north and level. (See Astronomy Basics forhelponfinding
north).
4

6
Input the necessary date and time information as
instructed by the hand control. Press ENTER after
each entry. The NexStar will also ask for time zone
and location information. Use the UP and Down scroll
buttons to select from the various options, pressing
ENTER after each selection. (See Hand Control
section for detailed ali
g
nment
p
rocedures
)
.
Up and Down
Scroll Buttons
Direction
Buttons
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6
Alignment Star
Star Pointer Finderscope
Press the TOUR button on the hand control. The hand control
will display a list of objects that are visible for the date and
location entered. Press INFO to read information about the
object displayed. Press the DOWN scroll key to display the
next object. Press ENTER to slew to (go to) the displayed
object.
The NexStar will automatically pick an alignment star and slew
the telescope close to that star. Once there, the display will ask
you to use the arrow buttons to aim the Star Pointer at the star. I
f
the star is not visible (perhaps behind a tree), press UNDO to
select a new star. Next, center the star in the eyepiece and press
ALIGN. Repeat these steps for the second star alignment. When
complete, display will read "Alignment Successful"
Alignment Successful"Alignment Successful"
Alignment Successful".
TOUR Button
Object List
Button
Catalog Keys
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1Optical Tube 6 Focuser Knob
2Liquid Crystal Display 7Straight Through Photographic Adapter
3Hand Control 8Flip Mirror Control
4ON/OFF Switch 9Eyepiece
5Battery Compartment 10 Star Pointer Finderscope
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2
3
5
10
6
7
8
9
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The NexStar 4 comes completely pre-assembled and can be operational in a matter of minutes. The NexStar is conveniently
packaged in one reusable shipping carton that contains all of the following accessories:
• 25mm SMA Eyepiece – 1¼"
• Star Pointer Finderscope
• Computerized Hand Control with 4,000 Object Database
A
As ss se em mb bl li in ng gt th he eN Ne ex xS St ta ar r
Start by removing the telescope from its shipping carton and setting the round base on a flat table or surface. It is best to
carry the telescope by holding it from the lower portion of the fork arm and from the bottom of the base. Remove all of the
accessories from their individual boxes. Remember to save all of the containers so that they can be used to transport the
telescope. Before the batteries can be installed, the telescope tube should be positioned horizontal to the ground. To do this,
gently rotate the front of the tube upwards until it is level with the ground.
Powering the NexStar
The NexStar can be powered by eight AA batteries (not included), an optional 12v AC adapter or an optional car battery
adapter. The battery compartment is located in the center of the telescope's base (see figure 3-1).
To power the NexStar with batteries:
1. Remove the battery cover from the center of the base by
gently lifting up on the round portion of the cover.
2. Insert the batteries into the battery compartment of the base.
3. Reattach the battery compartment door by gently pushing
down on the cover until it snaps into place.
4. Turn on the power to the NexStar by flipping the switch,
located at the base of the fork arm, to the "On" position.
Battery Compartment
Cover
Figure 3-1: The NexStar 4 Battery Compartment

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The Hand Control
The hand control is located on the side of the fork arm and can be removed and used remotely or used while attached to the
fork. The hand control attaches to the fork arm by resting on two posts, located on the bottom of the hand control cradle,
and a clip inside the fork arm. To remove the hand control from the fork arm cradle, gently lift the hand control upwards
and pull out. To return the hand control into the fork arm, lower the hand control into the cradle so that the two holes in the
bottom of the hand control go over the posts on the bottom of the cradle, and the opening in the back of the hand control
slides over the clip inside the fork arm.
Once the telescope is powered up, the hand control can be used to move the optical tube in altitude (up and down) and
azimuth (side to side). Use the Up arrow directional button to move the telescope tube until it is roughly parallel to the
ground. This will make it more convenient to attach the necessary accessories as well as remove the front lens cover and
install batteries when they are needed.
You are now ready to attach the included visual accessories onto the telescope optical tube.
The Eyepiece
The eyepiece, or ocular, is the optical element that magnifies the
image focused by the telescope. The NexStar 4 has an internal
diagonal mirror that diverts light to the eyepiece barrel on top of
the telescope's rear cell. The eyepiece fits into the barrel built-in
to the rear cell. To install the eyepiece:
1. Loosen the thumbscrew on the eyepiece barrel so it does not
obstruct the inner diameter of the barrel.
2. Slide the chrome portion of the eyepiece into the eyepiece barrel.
3. Tighten the thumbscrew to hold the eyepiece in place.
To remove the eyepiece, loosen the thumbscrew on the star
diagonal and slide the eyepiece out.
Eyepieces are commonly referred to by focal length and barrel
diameter. The focal length of each eyepiece is printed on the
eyepiece barrel. The longer the focal length (i.e., the larger the
number) the lower the eyepiece power or magnification; and the
shorter the focal length (i.e., the smaller the number) the higher the
magnification. Generally, you will use low-to-moderate power
when viewing. For more information on how to determine power,
see the section on “Calculating Magnification.”
Barrel diameter is the diameter of the barrel that slides into the telescope's eyepiece barrel. The NexStar uses eyepieces with
a standard 1-1/4" barrel diameter.
As mentioned, the NexStar has an internal flip mirror that can divert light either through the eyepiece barrel at the top of the
rear cell or directly through the photographic opening at the back of the rear cell. Make sure that the flip mirror is in the
"up" position for viewing with an eyepiece and in the "down" position for taking photographs (see Astronomy Basics section
of the manual).
Figure 3-2 – The Rear Cell with Visual Accessories
Focuser Knob
StarPointerEyepiece
Flip Mirror Control
Diagonal
Barrel
Note:

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The Star Pointer Finderscope
The Star Pointer is the quickest and easiest way to point your telescope exactly at a desired object in the sky. It's like having
a laser pointer that you can shine directly onto the night sky. The Star Pointer is a zero magnification pointing tool that uses
a coated glass window to superimpose the image of a small red dot onto the night sky. While keeping both eyes open when
looking through the Star Pointer, simply move your telescope until the red dot, seen through the Star Pointer, merges with
the object as seen with your unaided eye. The red dot is produced by a light-emitting diode (LED); it is not a laser beam and
will not damage the glass window or your eye. The Star Pointer comes equipped with a variable brightness control, two axes
alignment control and a quick-release dovetail mounting bracket. Before the Star Pointer is ready to be used, it must be
attached to the telescope tube and properly aligned:
Star Pointer Installation
1. Locate the dovetail mounting bracket on the rear cell of the optical tube.
2. Slide the mounting track at the bottom of the Star Pointer over the dovetail portion of the bracket. It may be necessary
to loosen the two screws on the side of the mounting track before sliding it over the dovetail. The end of the Star
Pointer with the glass window should be facing out towards the front of the telescope.
3. Tighten the two screws on the side of the mounting track to secure the Star Pointer to the dovetail bracket.
Star Pointer Operation
The star pointer is powered by a long life 3-volt lithium battery (#CR2032) located underneath the front portion of the Star
Pointer. Like all finderscopes, the Star Pointer must be properly aligned with the main telescope before it can be used. This
is a simple process using the azimuth and altitude control knobs located on the side and bottom of the Star Pointer. The
alignment procedure is best done at night since the LED dot will be difficult to see during the day.
1. To turn on the Star Pointer, rotate the variable brightness control (see figure 3-3) clockwise until you here a
"click". To increase the brightness level of the red dot, continue rotating the control knob about 180º until it stops.
Remember to remove the plastic cover over the battery, and always turn the power off after you have found
an object. This will extend the life of both the battery and the LED.
2. Locate a bright star or planet and center it in a low power eyepiece in the main telescope.
3. With both eyes open, look through the glass window at the alignment star.
4. If the Star Pointer is perfectly aligned, you will see the red LED dot overlap the alignment star. If the Star Pointer
is not aligned, take notice of where the red dot is relative to the bright star.
Azimuth Control
Knob
Dovetail Mounting Bracket
Mounting Track
ON/OFF
Variable Brightness
Control
Altitude Control
Knob
Figure 3-3: The Star Pointer Finderscope with Mounting Bracket
Glass Window

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5. Without moving the main telescope, turn the Star Pointer's azimuth and altitude alignment controls until the red
dot is directly over the alignment star.
If the LED dot is brighter than the alignment star, it may make it difficult to see the star. Turn the variable brightness
control counterclockwise, until the red dot is the same brightness as the alignment star. This will make it easier to get an
accurate alignment. The Star Pointer is now ready to be used.

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The NexStar 4 has a removable hand controller built into the side of the fork arm designed to give you instant access to all
the functions the NexStar has to offer. With automatic slewing to over 4,000 objects, and common sense menu
descriptions, even a beginner can master its variety of features in just a few observing sessions. Below is a brief description
of the individual components of the NexStar 4 hand controller:
1. Liquid Crystal Display (LCD) Window: Has a dual-line, 16 character display screen that is backlit for comfortable
viewing of telescope information and scrolling text.
2. Align: Instructs the NexStar to use a selected star or object as an alignment position.
3. Direction Keys: Allows complete control of the NexStar in any direction. Use the direction keys to center objects in
the StarPointer finderscope and eyepiece.
4. Catalog Keys: The NexStar has a key on the hand control to allow direct access to each of the catalogs in its 4,000+
object database. The NexStar contains the following catalogs in its database:
Messier – Complete list of all Messier objects.
NGC – Select list of all the deep-sky objects in the Revised New General Catalog.
Figure 4-1
The NexStar Hand Control
1
2
3
4
5
6
7
8
11
12
9
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Caldwell – A combination of the best NGC and IC objects.
Planets - All 8 planets in our Solar System plus the Moon.
Stars – A compiled list of the brightest stars from the SAO catalog.
List – For quick access, all of the best and most popular objects in the NexStar database have been broken
down into lists based on their type and/or common name:
Named Stars Common name listing of the brightest stars in the sky.
Named Objects Alphabetical listing of over 50 of the most popular deep
sky objects.
Double Stars Numeric-alphabetical listing of the most visually stunning
double, triple and quadruple stars in the sky.
Variable Stars Select list of the brightest variable stars with the shortest
period of changing magnitude.
Asterisms A unique list of some of the most recognizable star
patterns in the sky.
5. Info:Displays coordinates and useful information about objects selected from the NexStar database.
6. Tour: Activates the tour mode, which seeks out all the best objects for a given month and automatically slews the
NexStar to those objects.
7. Enter: Pressing Enter allows you to select any of the NexStar functions, accept entered parameters and slew the
telescope to displayed objects.
8. Undo: Undo will take you out of the current menu and display the previous level of the menu path. Press Undo
repeatedly to get back to a main menu or use it to erase data entered by mistake.
9. Menu: Displays the many setup and utilities functions such as tracking rate and user defined objects and many
others.
10. Scroll Keys: Used to scroll up and down within any of the menu lists. A double arrow symbol on the right side of
the LCD indicates that the scroll keys can be used to view additional information.
11. Rate: Instantly changes the rate of speed of the motors when the direction buttons are pressed.
12. RS-232 Jack: Allows you to interface with a computer and control the NexStar remotely.
H
Ha an nd dC Co on nt tr ro ol lO Op pe er ra at ti io on n
This section describes the basic hand control procedures needed to operate the NexStar. These procedures are grouped into
three categories: Alignment, Setup and Utilities. The alignment section deals with the initial telescope alignment as well as
finding objects in the sky; the setup section discusses changing parameters such as tracking mode and tracking rate; finally,
the last section reviews all of the utility functions such as adjusting the telescopes slew limits and backlash compensation.
Alignment Procedure
In order for the NexStar to accurately point to objects in the sky, it must first be aligned with two known positions (stars) in
the sky. With this information, the telescope can create a model of the sky, which it uses to locate any object with known
coordinates.
Auto-Align
Auto-Align is the easiest way to get your NexStar aligned and ready to observe. Even if you do not know a single star in the
sky, the NexStar will align itself by guiding the user through the alignment procedure by asking for basic information like
the date, time and location. The NexStar will then automatically choose two stars for alignment and roughly center the stars
in the field of view of the Star Pointer. Before the telescope is ready to be aligned, it should be set up in an outside location
with all accessories (eyepiece and Star Pointer) attached and lens cover removed as described in the Assembly section of the
manual.
1. Once the NexStar is powered on the display will read NexStar Ready.Press ENTER to begin alignment.
The first time that the NexStar is used, it will request information to help identify the model of telescope. Once powered on,
the hand control will display the message Select Model
Select ModelSelect Model
Select Model. Use the Up and Down menu keys (10) to scroll through the
different NexStar models. Press ENTER when your NexStar model is displayed on the hand control. This information will
be retained for future use and will not be displayed again. If for some reason the incorrect model was selected or you wish

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to use your hand control on a different NexStar model, the Select Model utility feature allows you to re-select the proper
NexStar model from the displayed list (see Select Model later in this section).
2. Use the Up and Down scroll keys to select AutoAlign if it is not already displayed,and press ENTER.
3. The telescope will then ask you to use the direction keys (3) to level the telescope tube and point the front of the
telescope towards north. North can be found by finding the direction of the North Star (Polaris) or by using a compass.
You do not need to point at the North Star, only the north horizon. Alignment only needs to be approximate, however a
close alignment will make the auto alignment more accurate. Once the telescope is in the north and level position, press
ENTER.
4. The hand control display will then ask for the following information:
Location - The NexStar will display a list of cities to choose from. Choose the city from the database that is closest to
your current observing site. The city you choose will be remembered in the hand controls memory so that
it will be automatically displayed the next time an alignment is done. Alternatively, if you know the exact
longitude and latitude of your observing site, it can be entered directly into the hand control and
remembered for future use as well. To choose a location city:
 Use the Up and Down scroll keys to choose between City Database and Custom Site. City Database will allow
you to select the closest city to your observing site from a list of either international or U.S. location. Custom Site
allows you to enter the exact longitude and latitude of your observing site. Select City Database and press
ENTER.
 The hand control will allow you to choose from either U.S. or international locations. For a listing of U.S.
locations by state and then by city, press ENTER while United States
United StatesUnited States
United States is displayed. For international locations,
use the Up or Down scroll key to select International
InternationalInternational
International and press ENTER.
 To display a list of local cities, first select your state from the alphabetical listing (or a list of countries if
International locations was selected) and press ENTER.
 Choose the closest city to your location from the displayed list and press ENTER.
Time - Enter the current time for your area. You can enter either the local time (i.e. 8:00), or you can enter military
time (i.e. 20:00).
 Select PM or AM. If military time was entered, the hand control will bypass this step.
 Choose between Standard time or Daylight Savings time. Use the Up and Down scroll buttons (10) to toggle
between options.
 Select the time zone that you are observing from. Again, use the Up and Down buttons (10) to scroll through the
choices. For time zone information, refer to the Time Zone map in the appendix of this manual.
Date - Enter the month, day and year of your observing session. The display will read: mm/dd/yy.
• If the wrong information has been input into the hand control, the UNDO button will act as a backspace allowing
the user to re-enter information.
• The next time that your NexStar is Auto Aligned, the hand control will automatically display the last location
(either a city or longitude/latitude) that was entered. Pressing the UNDO button will allow you to go back and
select a new city location or longitude/latitude.
Based on this information, the NexStar will automatically select a bright star that is above the horizon and slew towards it. At
this point the telescope is only roughly aligned, so the alignment star should only be close to the field of view of the Star
Pointer finder. Once finished slewing, the display will ask you to use the arrow buttons to align the selected star with the red
dot in the center of the Star Pointer. If for some reason the chosen star is not visible (perhaps behind a tree or building) you
can press UNDO to select and slew to a different star. Once centered in the finder, press ENTER. The display will then
instruct you to center the star in the field of view of the eyepiece. When the star is centered, press ALIGN to accept this star
as your first alignment star. (There is no need to adjust the slewing rate of the motors after each alignment step. The NexStar
automatically selects the best slewing rate for aligning objects in both the Star Pointer and the eyepiece). After the first
alignment star has been entered the NexStar will automatically slew to a second alignment star and have you repeat the same
Helpful
Hints

15
procedure for that star. When the telescope has been aligned to both stars the display will read Alignment Successful
Alignment SuccessfulAlignment Successful
Alignment Successful,
and you are now ready to find your first object.
If the wrong star was centered and aligned to, the NexStar display will read Align Failed
Align FailedAlign Failed
Align Failed.Press UNDO to begin the
alignment procedure again.
If you are not sure if the correct star was centered, always remember that the alignment star will be the brightest
star nearest the field of view of the finder. There may be other fainter stars visible that are closer to the center of the
Star Pointer, but the actual alignment star will be obviously brighter than any other star in the area.
For the best possible pointing accuracy, always center the alignment stars using the up arrow button and the right
arrow button. Approaching the star from this direction when looking through the eyepiece will eliminate much of the
backlash between the gears and assure the most accurate alignment possible.
Two Star Alignment
With the two-star alignment method, the NexStar requires the user to know the positions of only two bright stars in order to
accurately align the telescope with the sky and begin finding objects. Here is an overview of the two-star alignment
procedure:
1. Once the NexStar is powered on, use the Up and Down scroll keys to select Two
TwoTwo
Two-
--
-Star Align
Star AlignStar Align
Star Align,and press
ENTER.
2. The NexStar display will ask you to move the telescope tube until it is horizontal to the ground. To do this, use
the direction keys (3) to move the telescope until it is roughly level with the ground. Press ENTER.
3. The SELECT STAR 1
SELECT STAR 1SELECT STAR 1
SELECT STAR 1 message will appear in the top row of the display. Use the Up and Down scroll keys (10) to
select the star you wish to use for the first alignment star. Press ENTER.
4. NexStar then asks you to center in the eyepiece the alignment star you selected. Use the direction buttons to slew
the telescope to the alignment star and carefully center the star in the eyepiece.
5. Once the alignment star is centered in the field of view of the eyepiece, press the ALIGN key (2) to accept this
position.
6. NexStar will then ask you to select and center a second alignment star and press the ALIGN key. It is best to
choose alignment stars that are a good distance away from one another. Stars that are at least 40º to 60º apart from
each other will give you a more accurate alignment than stars that are close to each other.
Once the second star alignment is completed properly, the display will read Alignment Successful
Alignment SuccessfulAlignment Successful
Alignment Successful, and you will hear the
tracking motors turn-on and begin to track.
Quick-Align
Quick-Align allows you to input all the same information as you would for the AutoAlign procedure. However, instead of
slewing to two alignment stars for centering and alignment, the NexStar bypasses this step and simply models the sky based
on the information given. This will allow you to roughly slew to the coordinates of bright objects like the moon and planets
and gives the NexStar the information needed to track objects in altazimuth in any part of the sky. Quick-Align is not meant
to be used to accurately locate small or faint deep-sky objects or to track objects accurately for photography. Note: Once a
Quick-Align has been done, you can use the Re-alignment feature (see below) to improve your telescopes pointing and
tracking accuracy.
To use Quick-Align:
1. Select Quick-Align from the alignment options.
2. Use the arrow buttons to level the tube and position the telescope tube towards north and press ENTER.
3. The hand control will then ask you to input all the same time and location information as you would for the
AutoAlign procedure.
Once entered, the NexStar will model the sky based on this information and display Alignment Successful
Alignment SuccessfulAlignment Successful
Alignment Successful.
O
bserving
T
Ti ip ps s

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NexStar Re-Alignment
The NexStar has a re-alignment feature which allows you to replace either of the two original alignment stars with a new
star or celestial object. This can be useful in several situations:
• If you are observing over a period of a few hours, you may notice that your original two alignment stars have
drifted towards the west considerably. (Remember that the stars are moving at a rate of 15º every hour).
Aligning on a new star that is in the eastern part of the sky will improve your pointing accuracy, especially on
objects in that part of the sky.
• If you have aligned your telescope using the Quick-Align method, you can use re-align to align to two actual
objects in the sky. This will improve the pointing accuracy of your telescope without having to re-enter
addition information.
To replace an existing alignment star with a new alignment star:
1. Select the desired star (or object) from the database and slew to it.
2. Carefully center the object in the eyepiece.
3. Once centered, press the UNDO button until you are at the main menu.
4. With NexStar Ready displayed, press the ALIGN key on the hand control.
5. The display will then ask you which alignment star you want to replace.
6. Use the UP and Down scroll keys to select the alignment star to be replaced, and press ENTER. It is usually
best to replace the star closest to the new object. This will space out your alignment stars across the sky.
7. Press ALIGN to make the change.
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Selecting an Object
Now that the telescope is properly aligned, you can choose an object from any of the catalogs in the NexStar's extensive
database. The hand control has a key designated for each of the catalogs in its database. There are two ways to select objects
from the database: scrolling through the named object lists and entering object numbers.
• Pressing the LIST key on the hand control will access all objects in the database that have common names or
types. Each list is broken down into the following categories: Named Stars, Named Object, Double Stars,
Variable Stars and Asterisms. Selecting any one of these options will display an alpha-numeric listing of the
objects under that list. Pressing the Up and Down keys allows you to scroll through the catalog to the desired
object.
• Pressing any of the catalog keys (M, CALD, NGC, or STAR) will display a blinking cursor below the name
of the catalog chosen. Use the numeric key pad to enter the number of any object within these standardized
catalogs. For example, to find the Orion Nebula, press the "M" key and enter "042".
• Pressing the PLANET button will allow you to use the UP and DOWN arrow keys to scroll through and
select the eight planets as well as the moon.
To download a list of all the stars contained in the STAR Catalog with SAO number cross references, logon to our web site
at www.celestron.com.
Slewing to an Object
Once the desired object is displayed on the hand control screen, you have two options:
1. Press the INFO Key. This will give you useful information about the selected object such as magnitude,
constellation and fascinating facts about many of the objects.
More
Information

17
The speed at which information scrolls across the hand control display can be changed while the information is being
viewed:
• Press the “1” key repeatedly to speed up the scroll speed.
• Press the “4” key repeatedly to slow down the scroll speed.
• Press the “7” key to freeze and unfreeze the information on the display.
2. Press the ENTER Key. This will automatically slew the telescope to the coordinates of the object. While the
telescope is slewing to the object, the user can still access many of the hand control functions (such as displaying
information about the object).
If you slew to an object that is below the horizon, NexStar will notify you by displaying a message reminding you that you
have selected an object outside of your slew limits (see Slew Limits in the Utility Features section of the manual). Press
UNDO to go back and select a new object. Press ENTER to ignore the message and continue the slew. The NexStar hand
control will only display objects that are below the horizon if the Filter Limits are set below 0º in altitude. See Filter Limits
in the Utility Feature section of the manual for more information on setting the filter limits.
Caution: Never slew the telescope when someone is looking into the eyepiece. The telescope can move at fast slew
speeds and may hit an observer in the eye.
Object information can be obtained without having to do a star alignment. After the telescope is powered on, pressing any
of the catalog keys allows you to scroll through object lists or enter catalog numbers and view the information about the
object as described above.
Tour Mode
The NexStar includes a tour feature which automatically allows the user to choose from a list of interesting objects based on
the date and time in which you are observing. The automatic tour will display only those objects that are within your set
filter limits. To activate the Tour mode, press the TOUR key (6) on the hand control. The NexStar will display the best
objects to observe that are currently in the sky.
• To see information and data about the displayed object, press the INFO key.
• To slew to the object displayed, press ENTER.
• To see the next tour object, press the Down key.
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The NexStar has four direction buttons in the center of the hand control which control the telescope motion in altitude (up
and down) and azimuth (left and right). The telescope can be controlled at nine different speed rates.
1=2x 6=.5º/sec
2=4x 7=1º/sec
3=8x 8=2º/sec
4=16x 9=4º/sec
5=32x
Rate Button
Pressing the RATE key (11) allows you to instantly change the speed rate of the motors from high speed slew rate to precise
guiding rate or anywhere in between. Each rate corresponds to a number on the hand controller key pad. The number 9 is
the fastest rate (4º per second, depending on power source) and is used for slewing between objects and locating alignment
stars. The number 1 on the hand control is the slowest rate (2x sidereal) and can be used for accurate centering of objects in
the eyepiece. To change the speed rate of the motors:
Nine available slew speeds

18
• Press the RATE key on the hand control. The LCD will display the current speed rate.
• Press the number on the hand control that corresponds to the desired speed.
The hand control has a "double button" feature that allows you to instantly speed up the motors without having to choose a
speed rate. To use this feature, simply press the arrow button that corresponds to the direction that you want to move the
telescope. While holding that button down, press the opposite directional button. This will increase the speed to the
maximum slew rate.
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The NexStar contains many user defined setup functions designed to give the user control over the telescope's many
advanced features. All of the setup and utility features can be accessed by pressing the MENU key and scrolling through the
options:
Tracking Mode - Once the NexStar is aligned the tracking motors will automatically turn on and begin tracking
the sky. However, the tracking can be turned off for terrestrial use:
Alt-Az This is the default tracking rate and is used when the telescope is placed on
a flat surface or tripod without the use of an equatorial wedge. The
telescope must be aligned with two stars before it can track in Alt-Az.
EQ North Used to track the sky when the telescope is polar aligned using an
equatorial wedge in the Northern Hemisphere.
EQ South Used to track the sky when the telescope is polar aligned using an
equatorial wedge in the Southern Hemisphere.
Off When using the telescope for terrestrial (land) observation, the tracking
can be turned off so that the telescope never moves.
Tracking Rate - In addition to being able to move the telescope with the hand control buttons, the NexStar will
continually track a celestial object as it moves across the night sky. The tracking rate can be changed
depending on what type of object is being observed:
Sidereal This rate compensates for the rotation of the earth by moving the
telescope at the same rate as the rotation of the earth, but in the opposite
direction. When the telescope is polar aligned, this can be accomplished
by moving the telescope in Right Ascension only. When mounted in Alt-
Az mode, the telescope must make corrections in both R.A. and
declination.
Lunar Used for tracking the moon when observing the lunar landscape.
Solar Used for tracking the Sun when solar observing using a proper solar filter.
View Time-Site -View Time-Site will display the last saved time and longitude/latitude entered in the hand control.
Sidereal Time –Displays the Sidereal time for your current time and location. This is useful for knowing the right
ascension of celestial objects that are located on the local meridian at that time.
Filter Limits – When an alignment is complete, the NexStar automatically knows which celestial objects are above the
horizon. As a result, when scrolling through the database lists (or selecting the Tour function), the NexStar hand control
will display only those objects that are known to be above the horizon when you are observing. You can customize the
object database by selecting altitude limits that are appropriate for your location and situation. For example, if you are
observing from a mountainous location where the horizon is partially obscured, you can set your minimum altitude limit to
read +20º. This will make sure that the hand control only displays objects that are higher in altitude than 20º.

19
If you want to explore the entire object database, set the maximum altitude limit to 90º and the minimum limit to –90º. This
will display every object in the database lists regardless of whether it is visible in the sky from your location.
User Defined Objects - The NexStar can store up to 50 different user defined objects in its memory. The objects can
be daytime land objects or an interesting celestial object that you discover that is not included
in the regular database. There are several ways to save an object to memory depending on
what type of object it is:
Save Sky Object: The NexStar stores celestial objects to its database by saving its right ascension and
declination in the sky. This way the same object can be found each time the telescope is
aligned. Once a desired object is centered in the eyepiece, simply scroll to the "Save Sky
Save SkySave Sky
Save Sky
Obj"
Obj"Obj"
Obj" command and press ENTER. The display will ask you to enter a number between 1-25
to identify the object. Press ENTER again to save this object to the database.
Save Land Object: The NexStar can also be used as a spotting scope on terrestrial objects. Fixed land objects
can be stored by saving their altitude and azimuth relative to the location of the telescope at
the time of observing. Since these objects are relative to the location of the telescope, they
are only valid for that exact location. To save land objects, once again center the desired
object in the eyepiece. Scroll down to the "Save Land Obj
Save Land ObjSave Land Obj
Save Land Obj" command and press
ENTER. The display will ask you to enter a number between 1-25 to identify the object.
Press ENTER again to save this object to the database.
Enter R.A. - Dec: You can also store a specific set of coordinates for an object just by entering the R.A. and
declination for that object. Scroll to the "Enter RA
Enter RAEnter RA
Enter RA-
--
-DEC "
DEC "DEC "
DEC " command and press ENTER.
The display will then ask you to enter first the R.A. and then the declination of the desired
object.
GoTo Object: To go to any of the user defined objects stored in the database, scroll down to either GoTo
GoToGoTo
GoTo
Sky Obj
Sky ObjSky Obj
Sky Obj or Goto Land Obj
Goto Land ObjGoto Land Obj
Goto Land Obj and enter the number of the object you wish to select and
press ENTER. NexStar will automatically retrieve and display the coordinates before
slewing to the object.
To replace the contents of any of the user defined objects, simply save a new object using one of the existing identification
numbers; NexStar will replace the previous user defined object with the current one.
Get RA/DEC - Displays the right ascension and declination for the current position of the telescope.
Get Alt-Az - Displays the relative altitude and azimuth for the current position of the telescope.
Goto R.A/ Dec - Allows you to input a specific R.A. and declination and slew to it.
Goto Alt-Az - Allows you to enter a specific altitude and azimuth position and slew to it.
To store a set of coordinates (R.A./Dec) permanently into the NexStar database, save it as a User Defined Object as
described above.
Helpful
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Observing
Tip!

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Scrolling through the MENU options will also provide access to several advanced utility functions such as anti-backlash
compensation and slew limits.
Setup Time-Site -Allows the user to customize the NexStar display by changing time and location parameters (such as
time zone and daylight savings).
Anti-backlash – All mechanical gears have a certain amount of backlash or play between the gears. This play is evident
by how long it takes for a star to move in the eyepiece when the hand control arrow buttons are pressed (especially when
changing directions). The NexStar's anti-backlash features allows the user to compensate
for backlash by inputting a value which quickly rewinds the motors just enough to
eliminate the play between gears. The amount of compensation needed depends on the
slewing rate selected; the slower the slewing rate the longer it will take for the star to
appear to move in the eyepiece. Therefore, the anti-backlash compensation will have to be
set higher. You will need to experiment with different values; a value between 20 and 50
is usually best for most visual observing, whereas a higher value may be necessary for
photographic guiding.
To set the anti-backlash value, scroll down to the anti-backlash option and press ENTER.
Enter a value from 0-100 for both azimuth and altitude directions and press ENTER after
each one to save these values. NexStar will remember these values and use them each time
it is turned on until they are changed.
Slew Limits – Sets the limits in altitude that the telescope can slew without displaying a
warning message. The slew limits prevent the telescope tube from slewing to an object
below the horizon or slewing to an object that is high enough that the tube might hit one of
the tripod legs. However, the slew limits can be customized depending on your needs.
For example, if you would like to slew to an object that is close to the zenith and are certain
that the tube will not hit the tripod legs, you can set the slew limits to 90º in altitude. This
will allow the telescope to slew to any object above the horizon without warning.
Direction Buttons –The direction a star moves in the eyepiece varies depending on the
accessories being used. This can create confusion when guiding on a star using an off-axis
guider versus a straight through guide scope. To compensate for this, the direction of the
drive control keys can be changed. To reverse the button logic of the hand control, press
the MENU button and select Direction Buttons from the Utilities menu. Use the Up/Down
arrow keys (10) to select either the Azimuth buttons (left and right) or Altitude buttons (up
and down) and press ENTER. Pressing ENTER again will reverse the direction of the hand
control buttons from their current state. Direction Buttons will only change the eyepiece
rates (rate 1-6) and will not affect the slew rates (rate 7-9).
Light Control – This feature allows you to turn off both the red key pad light and LCD display for daytime use to
conserve power and to help preserve your night vision.
Select Model – The first time the NexStar is powered on, the hand control display allows you to select your NexStar
from a list of different models. If for some reason the incorrect model was selected or you wish to use your hand control on
a different NexStar model, the Select Model utility feature allows you to re-select the proper NexStar model from the
displayed list. Once the correct NexStar model has been selected the power needs to be restarted before beginning the
alignment procedure. The Select Model feature will return the hand control to its original factory settings. Parameters such
as backlash compensation values along with slew and filter limits will be reset. However, stored parameters such as user
defined objects will remain saved even after the model has been changed.
RS-232 - The NexStar has a RS-232 port located on the bottom of the hand control that allows it to communicate with
many astronomy computer programs such as The Sky by Software Bisque. Before attempting to create a link with a
computer, select the RS-232 option and press Enter.
SETUP TIME-SITE
A Z M P O S IT IV E
AZM NEGATIVE
A L T P O S ITIV E
ALT NEGATIVE
ANTI-BACKLASH
SLEW ALT MAX
SLEW ALT MIN
SLEW LIMITS
AZM BUTTONS
ALT BUTTONS
DIRECTION BUTTONS
DISPLAY OFF
DISPLAY ON
KEY PAD OFF
KEY PAD ON
LIGHT CONTROL
SELECT MODEL
UTILITIES
MENU