Celestron NexStar HC User Manual

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L

INTRODUCTION ........................................................................................................................................ 4

ARNING

W

QUICK SETUP............................................................................................................................................. 5

ASSEMBLY .................................................................................................................................................. 8

SSEMBLING THE NEXSTAR

A

Powering the NexStar ............................................................................................................................8

The Hand Control .................................................................................................................................. 9

The Eyepiece .......................................................................................................................................... 9

The Star Pointer Finderscope .............................................................................................................. 10

NEXSTAR HC MODEL ...........................................................................................................................12

HE HAND CONTROL

T

Rate Button........................................................................................................................................... 13

Utility Features .................................................................................................................................... 13

GuideStar Software.............................................................................................................................. 14

NEXSTAR GT MODEL............................................................................................................................. 15

AND CONTROL OPERATION

H

Alignment Procedure ...........................................................................................................................16

BJECT CATALOG

O

Selecting an Object ..............................................................................................................................18

Slewing to an Object ............................................................................................................................ 18

Tour Mode............................................................................................................................................ 19

IRECTION BUTTONS

D

Rate Button........................................................................................................................................... 19

ETUP PROCEDURES

S

Tracking Mode ..................................................................................................................................... 20

Tracking Rate.......................................................................................................................................20

Date/Time............................................................................................................................................. 21

User Defined Objects ........................................................................................................................... 21

Get RA/DEC......................................................................................................................................... 21

Get Alt-Az.............................................................................................................................................21

Goto R.A/Dec ....................................................................................................................................... 21

Goto Alt-Az........................................................................................................................................... 22

TILITY FEATURES

U

Cord Wrap
Anti-backlash
Model Select

Hand Control Command Tree.............................................................................................................. 23

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........................................................................................................................ 8

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TELESCOPE BASICS ............................................................................................................................... 24

MAGE ORIENTATION

I

OCUSING

F

ALCULATING MAGNIFICATION

C

ETERMINING FIELD OF VIEW

D

ENERAL OBSERVING HINTS

G

ASTRONOMY BASICS

HE CELESTIAL COORDINATE SYSTEM

T

OTION OF THE STARS

M

................................................................................................................................................. 25

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.................................................................................................................... 26

................................................................................................................................. 27

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............................................................................................................................. 28

ii

OLAR ALIGNMENT (WITH OPTIONAL WEDGE

P

Photography with the NexStar 4 .......................................................................................................... 30

Finding the North Celestial Pole .........................................................................................................31

) .........................................................................................29

CELESTIAL OBSERVING....................................................................................................................... 32

BSERVING THE MOON

O

BSERVING THE PLANETS

O

BSERVING THE SUN

O

BSERVING DEEP SKY OBJECTS

O

EEING CONDITIONS

S

Transparency .......................................................................................................................................33

Sky Illumination ...................................................................................................................................33

Seeing...................................................................................................................................................34

TELESCOPE MAINTENANCE............................................................................................................... 35

ARE AND CLEANING OF THE OPTICS

C

OPTIONAL ACCESSORIES .................................................................................................................. 36

APPENDIX A - TECHNICAL SPECIFICATIONS................................................................................ 39

APPENDIX B - GLOSSARY OF TERMS ............................................................................................... 40

APPENDIX C – MAPS OF TIME ZONES .............................................................................................. 43

SKY MAPS..................................................................................................................................................45

............................................................................................................................. 32

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iii

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 combine with Celestron’s legendary optics to 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

Never look directly at the sun with the naked eye or with a telescope (unless you have the proper solar 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

.

4

3

StarPointer Eyepiece

1

2

Remove the NexStar from its packaging and place
the base on a sturdy, level surface. Remove the
accessories from their individual boxes.

Battery Compartment
Cover

4

Flip Mirror

Attach the included accessories (eyepiece and Star
Pointer finderscope) and remove the front lens
cover. Turn-on the Star Pointer by rotating the dial
on the side. (For instructions on aligning the Star
Pointer see the

Assembly

Focuser Knob

section of the manual).

Rotate the tube so it is level with the ground. Lift
the battery compartment cover to install batteries.
Power the NexStar using the switch next to the 12v
outlet at the base of the fork arm.

6

Once powered on, the display will read
Press ENTER to
display will ask you to move the telescope tube so that it is
level with the ground and facing the north horizon. Use
the UP and Down arrow buttons to position the telescope
North and level. (See
North). The first time the NexStar is powered-on, you may
be prompted to select your telescope model. If so, see the
section on hand control operation for instruction.

AutoAlign

the NexStar. The hand control

Astronomy Basics

NexStar Ready.

for help on finding

5

g

k

f

5

7

Direction
Buttons

Up and Down
Scroll Buttons

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
section for detailed ali

nment procedures).

6

Hand Control

Catalog Keys

Object List
Button

TOUR Button

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.

Alignment Star

The NexStar will automatically pick an alignment star and slew
the telescope close to that star. Once there, the display will as
you to use the arrow buttons to aim the Star Pointer at the star. I
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"

.

6

8

7

6

9

10

1

2

3

5

4

1 Optical Tube 6 Focuser Knob

2 Liquid Crystal Display 7 Straight Through Photographic Adapter

3 Hand Control 8 Flip Mirror Control

4 ON/OFF Switch 9 Eyepiece

5 Battery Compartment 10 Star Pointer Finderscope

7

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 – 1

• Star Pointer Finderscope and Mounting Bracket

• The Sky® for Celestron Astronomy Software

"

¼

AAsssseemmbblliinngg tthhee NNeexxSSttaarr

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

8

Note:

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).

Press UNDO (for GT model only). This will bypass the normal alignment procedures and will still allow you to control

•

the telescope.

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).

StarPointer Eyepiece

Diagonal

Barrel

Flip Mirror Control

Focuser Knob

Figure 3-2 – The Rear Cell with Visual Accessories

9

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:

Variable Brightness

Altitude Control

Star Pointer Installation

1. First, remove the two 8-32 x ¼" screws located on the top portion of the telescope's rear cell.

2. Locate the square dovetail bracket that has the proper curvature for the NexStar tube and align the holes with the two

holes in the telescope body.

3. Use the two 8-32 x ¼" screws to tighten down the bracket to the rear cell.

4. Once the bracket is mounted, 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.

5. 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.

2. Locate a bright star or planet and center it in a low power eyepiece in the main telescope.

ON/OFF

Control

Mounting Track

Knob

Dovetail Mounting Bracket

Figure 3-3: The Star Pointer Finderscope with Mounting Bracket

Glass Window

Azimuth Control
Knob

10

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.

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

and always turn the power off after you have found an object. This will extend the life of both the battery and the
LED.

. Remember to remove the plastic cover over the battery,

11

4

The NexStar 4 HC telescope is a precision scientific instrument that will allow you to enjoy viewing numerous objects in the
night sky — planets, nebulae, star clusters, galaxies and more. Equipped with high speed motors and hand control, the NexStar
HC allows you to remotely move your telescope to desired objects quickly and accurately. At a touch of a button, you can slew
your telescope across the sky in a matter of seconds and continuously track objects as the Earth rotates beneath them. The
NexStar HC is fully upgradeable and can be equipped with the optional NexStar Hand Control with a database of over 4,000
objects (see the Optional Accessories section of this manual).

5

1

2

3

Figure 4-1

The NexStar HC Hand Control

TThhee HHaanndd CCoonnttrrooll

The NexStar HC has a removable hand control that gives the user quick access to all the motion controls the NexStar HC offers.
Below is a brief description of the individual components of the NexStar HC hand controller:

1.

2.

3.

Star Key Activation Light:

control are active.

Direction Buttons:

telescope from object to object or for centering objects in the eyepiece.

Rate:

Instantly changes the rate of speed of the motors when the direction buttons are pressed. Press this button

repeatedly to cycle through the speeds of the motors.

Indicates that the

Allows complete control of the NexStar in any direction. Use the direction keys to move the

Star

button has been pressed and the utility functions on the hand

12

4.

5.

Star Key:

keys and backlash compensation.

Hand Control Slew Rate Indicator Lights:

button is pressed.

Gives the user access to the utility functions of the hand control, such as changing the direction of the arrow

Displays the speed at which the telescope will move when each direction

Rate Button

Pressing the RATE key (3) allows you to instantly change the speed rate of the motors from high speed slew rate to precise
centering rate or two speeds in between. Each rate corresponds to one of the indicator LED lights (5) on the hand control. From
left to right, the corresponding speeds are as follows:

Rate

1 For fine centering of objects in the eyepiece

2 For scanning around for objects in the eyepiece

3 For centering bright stars in the Star Pointer

4 For slewing around the sky from object to object

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 slew rate to approximately 1.5º per
second (equal to the third rate on the hand control). This feature will only function if the telescope is currently set at a speed rate
of 1 or 2.

Utility Features

The NexStar HC hand control comes with a Star function key that allows you to change certain parameters of the hand controls
functions, such as the directional logic of the arrow keys, backlash compensation of the motor gears and azimuth tracking.

Direction Buttons:

1. Press the
button has been pressed. When the button has been pressed, the four direction buttons (2) will be non-operational until
the button is pressed again.

2. Press the

3. Press the

Anti-backlash

1. Press the

2. Use the Right and Left arrow keys to speed up or slow down the initial speed of the azimuth motors when the arrow
buttons are pressed. For example, if it takes a star too long to move in the eyepiece when the hand control arrow buttons
are pressed, then press the Right arrow button to speed up the initial motor speed. The buttons can be pressed repeatedly
to increase the initial motor speed even more.

When looking at a star through an eyepiece or star diagonal, the direction that the star moves when the Up

and Down arrow buttons are pressed will be reversed from when the same object is being centered in the
Star Pointer Finderscope. For example, when a star is being centered in the telescope's eyepiece, it may
appear to move upward when the down arrow button is pressed (and visa-versa) even though the telescope
tube is actually moving downward. This is why it is convenient to be able to change the arrow button
direction when switching from using the Star Pointer to the eyepiece. To reverse the direction of the Up and
Down arrow buttons:

STAR

key on the hand control. The activation light (1) on the hand control will light up to indicate that the

RATE

button on the hand control.

STAR

key on the hand control to activate the direction buttons.

– 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 feature allows the user to compensate for backlash by
having the hand control quickly rewind 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. To change the backlash compensation:

STAR

key on the hand control.

13

3. Use the UP and Down arrow keys to speed up or slow down the initial speed of the altitude motors when the arrow
buttons are pressed.

4. Press the

GuideStar Software

The NexStar HC has an RS-232 port on the back of the hand control, allowing it to be controlled using the GuideStar telescope
control software. Linking the NexStar to a computer requires the use of a RS-232 cable. Connect the phone jack connector to the
RS-232 port in the hand control and the 9-pin connector to the back of your computer. Once connected, install the GuideStar CD­ROM onto your computer and follow the on-screen instruction. The GuideStar software gives you all the "Go-To" features of the
NexStar GT hand control including a 4,000 object database, AutoAlign based on date and location, and helpful information for
hundreds of objects. For information on using many of the GuideStar features, refer to the AutoAlign instructions in the NexStar
GT section of the manual. The GuideStar software also has help buttons to explain many of the commonly used fields.

STAR

key on the hand control again to activate the direction buttons again.

14

The NexStar GT 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 GT hand controller

:

Liquid Crystal Display (LCD) Window:

1.

Has a dual-line, 16 character display screen that is backlit for comfortable

viewing of telescope information and scrolling text.

Align:

2.

3.

Instructs the NexStar to use a selected star or object as an alignment position.

Direction Keys:

Allows complete control of the NexStar in any direction. Use the direction keys to move the

telescope to the initial alignment stars or for centering objects in the eyepiece.

1

7

2

8

3

9

4

10

5

11

6

12

The NexStar Hand Control

Figure 5-1

4.

Catalog Keys:

The NexStar has keys 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:

15

– Complete list of all Messier objects.

Messier

Complete list of all the deep-sky objects in the Revised New General Catalog.

NGC –
Caldwell –
Planets -
Stars
List

down into lists based on their type and/or common name:

Info

5.

6.

7.

8.

9.

10.

11.

12.

Displays coordinates and useful information about objects selected from the NexStar database.

:

Tour:

Activates the tour mode, which seeks out all the best objects for a given month and automatically slews the

NexStar to those objects.

Enter:

Pressing Enter allows you to selects any of the NexStar functions and accept entered parameters.

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.

Menu:

others.

Scroll Keys:

sub-menus.

Rate:

Instantly changes the rate of speed of the motors when the direction buttons are pressed.

RS-232 Jack

A combination of the best NGC and IC objects.

All 8 planets in our Solar System plus the Sun and moon.

– A compiled list of the brightest stars from the SAO catalog.

– For quick access, all of the best and most popular objects in the NexStar database have been broken

Alignment Stars
Named Objects

Double Stars

Variable Stars

Asterisms

Displays the many setup and utilities functions such as tracking rate and user defined objects and many

Used to scroll up and down within any of the menu lists. Using these keys will scroll through those

: Allows you to interface with a computer and control the NexStar remotely.

Common name listing of the brightest stars in the sky.
Alphabetical listing of over 50 of the most popular deep
sky objects.
Numeric-alphabetical listing of the most visually stunning
double, triple and quadruple stars in the sky.
Select list of the brightest variable stars with the shortest
period of changing magnitude.
A unique list of some of the most recognizable star
patterns in the sky

.

HHaanndd CCoonnttrrooll OOppeerraattiioonn

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 utilities functions such as cordwrap and backlash compensation.

The first time that the NexStar is used, it will request information to help identify the model of telescope. Once initialized
(powered on), the hand control will display the message
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.

set at the factory to operate with your NexStar model. If so, there will be an addendum packaged with the hand
control. If your hand control has been pre-set, the display will read
simply press ENTER and continue to follow the Auto Align procedures below.

Select Model

Select Model

Select ModelSelect Model

. Use the Up and Down menu keys (10) to scroll

Note: your hand control may have been pre

NexStar Ready

NexStar Ready –––– Custom

NexStar Ready NexStar Ready

Custom,

Custom Custom

Alignment Procedure

In order for the NexStar to accurately point to objects in the sky, it must first be aligned to 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.

AAuuttoo--AAlliiggnn

Auto-Align is the easiest way to get the 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 about
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

and you can

16

Trouble

Shooting

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 , Press ENTER to begin alignment.

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 arrow 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:

- Enter the month, day and year of your observing session. The display will read:

Date

- Enter the current local time for your area and select PM or AM.

Time

mm/dd/yy

• 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. To enter a numeric time zone, select Zone and enter the number for the appropriate time zone.
For time zone information, refer to the Time Zone map in the appendix of this manual.

Finally, you must enter the location of your observing site. 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 can be saved in the hand controls
memory so that it only has to be entered once from any given location. 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:

1. When

Select Method

Select Method

Select MethodSelect Method

if it is not already displayed, and press ENTER.

City

City

CityCity

is displayed on the hand control screen, use the Up and Down scroll keys to select

Choose

Choose

Choose Choose

2. 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
Down scroll key to select

International

International

InternationalInternational

and press ENTER.

United States

United States

United StatesUnited States

is displayed. For international locations, use the Up or

3. 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.

4. Choose the closest city to your location from the displayed list and press ENTER.

The display will then ask if you would like to save this city for future use. If you press "Yes", the next time you AutoAlign
the telescope, you can select

User Defined

User Defined

User DefinedUser Defined

instead of the

Choose City

Choose City

Choose CityChoose City

. When

User Defined

User Defined

User DefinedUser Defined

is selected, the hand control
will allow you to choose from either the location cities that were saved or any individual longitude/latitude that was saved.
Use the UP and DOWN arrow keys to scroll through the stored cities, when the desired city is displayed, press ENTER. For
saved locations (longitudes/latitudes), enter the number (1-9) of the location coordinates that were saved.

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's field of view. 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 this
procedure for that star. When the telescope has been aligned to both stars the display will read

Alignment Successful

Alignment Successful

Alignment SuccessfulAlignment 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 Bad Alignment. Should this occur, the display
will automatically ask you to re-center the last alignment star and press ALIGN. If you believe that the wrong star may have
been centered (remember the alignment star will always be the brightest star nearest the field of view of the finder), then re­center the star and press ALIGN. If you wish to try aligning on a different star, press UNDO and the NexStar will select two
new alignment stars and automatically slew to the first star.

17

In order to accurately center the alignment star in the eyepiece, it may be necessary to decrease the slew rate of the motors
for fine centering. This is done by pressing the RATE key (11) on the hand controller then selecting the number that
corresponds to the speed you desire. (9 = fastest , 1 = slowest).

TThhiirrdd SSttaar

r

AAlliiggnnmmeennt

t

The NexStar has a third star alignment feature which allows you to replace either of the two original
alignment stars with a new star. 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.

When trying to locate a very faint or small object that may be difficult to find in the eyepiece, you can improve your

•

pointing accuracy by aligning to a third star that is nearest to the object you are trying to find.

To replace an existing alignment star with a new alignment star:

1. Locate and center the desired star in the eyepiece.

2. Select the centered star from the list of alignment stars in the hand control.

3. When the name of the centered star is displayed, press the ALIGN key on the hand control.

4. The display will then ask you which alignment star you want to replace.

5. Use the UP and Down scroll keys to select the alignment star to be replaced. It is usually best to replace the star
closest to the new star. This will space out your alignment stars across the sky.

6. Press ENTER to make the change.

More

Information

OObbjjeecctt CCaattaalloogg

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 (4) 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.

1. 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 (10) allows you to scroll through the catalog to the desired object.

2. 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".

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

and go to the NexStar page.

Slewing to an Object

Once the desired object is displayed in the hand control screen, you have two options:

18

Observing

Tip

Press the INFO Key

1.

declination, magnitude and most importantly, altitude above the horizon. (If a star alignment has not yet been
performed, the altitude will not be displayed).

The speed at which information scrolls across the hand control display can be changed while the information is being
viewed:

•

•

•

Press the ENTER Key

2.

Caution: Never slew the telescope when someone is looking into the eyepiece. The telescope can move at very 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, press the
UNDO key. Pressing any of the catalog keys allows you to scroll through object lists or enter catalog numbers as described
above. However, information such as R.A. and declination of planets and altitude above the horizon will not be displayed
unless the telescope is first properly aligned.

. This will give you useful information about the selected object such as R.A. and

Hold down the “1” key to speed up the scroll speed.
Hold down the “4” key to slow down the scroll speed.
Hold down the “7” key to freeze the information on the display.

. This will automatically slew the telescope to the coordinates of the object.

Tour Mode

The NexStar includes a tour feature which automatically allows the user to choose from a list of interesting objects based on
the month in which you are observing. The Tour mode is activated by pressing the TOUR key (6) on the hand control. Once
activated, simply use the scroll keys to select the current month and press ENTER. The NexStar will display from a list of
the best objects to observe based on the month entered.

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 Up key.

•

When going through any of the object catalogs in the database, you can easily find out which objects are above the horizon
and visible simply by pressing the INFO button when the desired object is displayed. This will display the objects altitude
above the horizon based on the date and time entered. Pressing the UP button once will display any scrolling text associated
with that object. The scrolling text can be viewed even if a star alignment has not been performed.

DDiirreeccttiioonn BBuuttttoonnss

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.

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 (1x sidereal) and can be used for accurate centering of objects in
the eyepiece and photographic guiding. To change the speed rate of the motors:

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 LCD will display "NexStar

•

Ready" indicating that the rate has been changed.

19

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 slew rate to
approximately 1º per second (equal to rate 7 on the hand control). This feature will not function if the telescope is currently
set at a speed rate of 8 or 9.

The slower slew rates (6 and lower) move the motors in the opposite direction than the faster slew rates (8 and 9). This is
done so that an object will move in the appropriate direction when looking into the eyepiece (i.e. pressing the right arrow
button will move the star towards the right in the field of view of the eyepiece). However, if any of the slower slew rates
(rate 6 and below) are used to center an object in the Star Pointer, you may need to press the opposite directional button to
make the telescope move in the correct direction.

1 = 2x 6 = .5º / sec
2 = 4x 7 = 1º / sec
3 = 8x 8 = 2º / sec
4 = 16x 9 = 4º / sec
5 = 32x

Nine available slew speeds

SSeettuupp PPrroocceedduurreess

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

Tracking Rate

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

EQ North

EQ South

Off

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:

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.

Used to track the sky when the telescope is polar aligned using an
equatorial wedge in the Northern Hemisphere.

Used to track the sky when the telescope is polar aligned using an
equatorial wedge in the Southern Hemisphere.

When using the telescope for terrestrial (land) observation, the tracking
can be turned off so that the telescope never moves.

20

Sidereal

Lunar

Solar

King

User Objects

.

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

Get Alt-Az

Goto R.A/ Dec

The NexStar can store up to 20 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:

Save Land Object

GoTo Sky Object:

GoTo Land Object:

- Displays the right ascension and declination for the current position of the telescope.

- Displays the relative altitude and azimuth for the current position of the telescope.

- Allows you to input a specific R.A. and declination and slew to it.

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 "

OOOObj

bj "

bj bj

to identify the object. Press ENTER again to save this object to the database.

: 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 "
ENTER. The display will ask you to enter a number between 1-9 to identify the object. Press
ENTER again to save this object to the database.

To go to any of the user defined sky objects stored in the database, scroll down to "

Sky

Sky Obj

SkySky

NexStar will automatically retrieve the coordinates and slew to the object.

To go to any of the user defined land objects stored in the database, scroll down to "

Land

Land Obj

LandLand

NexStar will automatically retrieve the coordinates and slew to the object.

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 Alt­Az mode, the telescope must make corrections in both R.A. and
declination.

Used for tracking the moon when observing the lunar landscape.

Used for tracking the Sun when solar observing using a proper solar filter.

As light passes through our atmosphere, atmospheric refraction affects the
apparent motion of objects across the sky. The King rate takes this into
account and compensates for the refraction of the atmosphere.

Save Sky

Save Sky

Save Sky Save Sky

command and press ENTER. The display will ask you to enter a number between 1-9

"

" "

Save Land Obj

Save Land Obj

Save Land ObjSave Land Obj

" and enter the number of the object you wish to select and press ENTER.

Obj

Obj Obj

" and enter the number of the object you wish to select and press ENTER.

Obj

Obj Obj

" command and press

GoTo

GoTo

GoToGoTo

GoTo

GoTo

GoToGoTo

21

Helpful

t

Hin

Goto Alt-Az

To store a set of coordinates (R.A./Dec) permanently into the NexStar database, save it as a User Defined Object as
described above.

- Allows you to enter a specific altitude and azimuth position and slew to it.

Observing

TTiipp

UUttiilliittyy FFeeaattuurreess

Scrolling through the MENU options will also provide access to several advanced utility functions within the NexStar such
as cord wrap and anti-backlash.

Cord Wrap

cord around the base of the telescope. The cord wrap menu has two settings; batteries and power cord. By default, the cord
wrap feature is set to "batteries" when the telescope is powered on. If using the NexStar with a AC adapter, change the
setting to "power cord", this will activate the cord wrap feature.

Anti-backlash

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
from 0-100 for both azimuth and altitude 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.

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.

Model Select –

list of different models. If for some reason the incorrect model was selected, the Model Select 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.
factory, it will say NexStar Ready - Custom when first turned-on. Do not use the Model Select feature to change the model
type; doing so may alter the telescope's pointing accuracy.

–

Cord wrap safeguards against the telescope slewing more than 360º in azimuth and wrapping the power

– All mechanical gears have a certain amount of backlash or play between the gears. This play is evident

Azm Backlash

Azm Backlash

Azm BacklashAzm Backlash

When the NexStar is first powered on, the hand control display allows you to select your NexStar from a

or

Alt Backlash

Alt Backlash

Alt BacklashAlt Backlash

NOTE:

If your hand control has been pre-set at the

and press ENTER. Enter a value

22

NexStar Ready

MENU

TRACKING MODE

ALT-AZ
EQ NORTH
EQ SO UTH
OFF

TRACKING RATE

SIDEREAL
SOLAR
LUNAR
KING

GET ALT-AZ
GET RA-DEC
GOTO ALT-AZ
GOTO RA-DEC
USER OBJECTS

GOTO SKY OBJECT
GOTO LAND OBJECT
SAVE SKY O BJECT
SAVE LAND OBJECT

CORD WRAP

ALIGNM ENT

AUTO ALIGN

NORTH & LEVEL

ENTER DATE

LIST

NAMED STARS
NAMED OBJECTS
DOUBLE STARS
VARIABLE STARS
ASTERISMS
TOUR
PLANETS

ENTER TIM E

SELECT METHOD

CHOOSE CITY

UNITED STATES

Choose State

Choose City

INTERNATIONA L

Choose Country

POW ER CORD
BATTERY

AZM BACKLASH
ALT BACKLASH
MODEL SELECT

Custom
NexStar 60
NexStar 70
NexStar 80
NexStar 114
NexStar 4"

USER DEFINED

ENTER LONG / LAT

Choose City

CHOOSE CITY
SELECT LOCATION

NexStar Menu Tree:

The following figure is a menu tree showing the sub-menus associated with the primary

command functions

23

A telescope is an instrument that collects and focuses light. The nature of the optical design determines how the light is focused.
Some telescopes, known as refractors, use lenses. Other telescopes, known as reflectors, use mirrors. The Maksutov-Cassegrain
optical system uses a combination of mirrors and lenses and is referred to as a compound or catadioptric telescope. This unique
design offers large-diameter optics while maintaining very short tube lengths, making them extremely portable. The Maksutov­Cassegrain system consists of a corrector plate, a spherical primary mirror, and a secondary mirror spot. Once light rays enter the
optical system, they travel the length of the optical tube three times.

A

A

ccuuttaawwaayy vviieeww ooff tthhee lliigghhtt ppaatthh ooff tthhe

Figure 6-1

e

MMaakkssuuttoovv--CCaasssseeggrraaiin

n

ooppttiiccaall ddeessiiggn

n

The optics of the NexStar have enhanced multi-layer coatings on the primary and secondary mirrors for increased reflectivity and
a multi coated corrector for the finest anti-reflection characteristics.

Inside the optical tube, a black tube extends out from the center hole in the primary mirror. This is the primary baffle tube and it
prevents stray light from passing through to the eyepiece or camera.

IImmaaggee OOrriieennttaattiioonn

The image orientation changes depending on how the eyepiece is inserted into the telescope. The NexStar uses three reflective
surfaces to bounce the light to the eyepiece. This produces an image that is right-side-up, but reversed from left-to-right (i.e.,
reversed). This is normal for the Maksutov-Cassegrain design.

orientation as seen with the

Fig 6-2a - Actual image

unaided eye

Fig 6-2b - Reversed from left to

right, as viewed through the

eyepiece

24

FFooccuussiinngg

The NexStar's focusing mechanism controls the primary mirror which is mounted on a ring
that slides back and forth on the primary baffle tube. The focusing knob, which moves the
primary mirror, is on the rear cell of the telescope just below the star diagonal and eyepiece.
Turn the focusing knob until the image is sharp. If the knob will not turn, it has reached the
end of its travel on the focusing mechanism. Turn the knob in the opposite direction until
the image is sharp. Once an image is in focus, turn the knob clockwise to focus on a closer
object and counterclockwise for a more distant object. A single turn of the focusing knob
moves the primary mirror only slightly. Therefore, it will take many turns (about 25) to go
from close focus (approximately 20 feet) to infinity.

For astronomical viewing, out of focus star images are very diffuse, making them difficult to
see. If you turn the focus knob too quickly, you can go right through focus without seeing
the image. To avoid this problem, your first astronomical target should be a bright object
(like the Moon or a planet) so that the image is visible even when out of focus. Critical
focusing is best accomplished when the focusing knob is turned in such a manner that the
mirror moves against the pull of gravity. In doing so, any mirror shift is minimized. For
astronomical observing, both visually and photographically, this is done by turning the focus
knob counterclockwise.

CCaallccuullaattiinngg MMaaggnniiffiiccaattiioonn

You can change the power of your telescope just by changing the eyepiece (ocular). To determine the magnification of your
telescope, simply divide the focal length of the telescope by the focal length of the eyepiece used. In equation format, the
formula looks like this:
Focal Length of Telescope (mm)
Magnification =
Focal Length of Eyepiece (mm)

Let’s say, for example, you are using the 25mm eyepiece. To determine the magnification you simply divide the focal length of
your telescope (the NexStar has a focal length of 1300mm) by the focal length of the eyepiece, 25mm. Dividing 1300 by 25
yields a magnification of 52 power.

Figure 6-3

The emblem on the end of

the focus knob shows the

correct rotational direction

for focusing the NexStar



.

Although the power is variable, each instrument under average skies has a limit to the highest useful magnification. The general
rule is that 60 power can be used for every inch of aperture. For example, the NexStar is 4" in diameter. Multiplying 4 by 60
gives a maximum useful magnification of 240 power. Although this is the maximum useful magnification, most observing is
done in the range of 20 to 35 power for every inch of aperture which is 80 to 140 times for the NexStar telescope.

DDeetteerrmmiinniinngg FFiieelldd ooff VViieeww

Determining the field of view is important if you want to get an idea of the angular size of the object you are observing. To
calculate the actual field of view, divide the apparent field of the eyepiece (supplied by the eyepiece manufacturer) by the
magnification. In equation format, the formula looks like this:

Apparent Field of Eyepiece
True Field =
Magnification

As you can see, before determining the field of view, you must calculate the magnification. Using the example in the previous
section, we can determine the field of view using the same 25mm eyepiece. The 25mm eyepiece has an apparent field of view of
52°. Divide the 52° by the magnification, which is 52 power. This yields an actual field of view of 1.0°.

To convert degrees to feet at 1,000 yards, which is more useful for terrestrial observing, simply multiply by 52.5. Continuing
with our example, multiply the angular field 1.0° by 52.5. This produces a linear field width of 52.5 feet at a distance of one
thousand yards. The apparent field of each eyepiece that Celestron manufactures is found in the Celestron Accessory Catalog
(#93685).



25

GGeenneerraall OObbsseerrvviinngg HHiinnttss

When working with any optical instrument, there are a few things to remember to ensure you get the best possible image.

Never look through window glass. Glass found in household windows is optically imperfect, and as a result, may vary in

•

thickness from one part of a window to the next. This inconsistency can and will affect the ability to focus your telescope.
In most cases you will not be able to achieve a truly sharp image, while in some cases, you may actually see a double image.

Never look across or over objects that are producing heat waves. This includes asphalt parking lots on hot summer days or

•

building rooftops.

Hazy skies, fog, and mist can also make it difficult to focus when viewing terrestrially. The amount of detail seen under

•

these conditions is greatly reduced. Also, when photographing under these conditions, the processed film may come out a
little grainier than normal with lower contrast and underexposed.

If you wear corrective lenses (specifically glasses), you may want to remove them when observing with an eyepiece

•

attached to the telescope. When using a camera, however, you should always wear corrective lenses to ensure the sharpest
possible focus. If you have astigmatism, corrective lenses must be worn at all times.

26

Up to this point, this manual covered the assembly and basic operation of your NexStar telescope. However, to
understand your telescope more thoroughly , you need to know a little about the night sky. This section deals with
observational astronomy in general and includes information on the night sky and polar alignment.

m

TThhee CCeelleessttiiaall CCoooorrddiinnaattee SSyysstteem

To help find objects in the sky, astronomers use a celestial coordinate system that is similar to our geographical
coordinate system here on Earth. The celestial coordinate system has poles, lines of longitude and latitude, and an
equator. For the most part, these remain fixed against the background stars.

The celestial equator runs 360 degrees around the Earth and separates the northern celestial hemisphere from the
southern. Like the Earth's equator, it bears a reading of zero degrees. On Earth this would be latitude. However, in the
sky this is referred to as declination, or DEC for short. Lines of declination are named for their angular distance above
and below the celestial equator. The lines are broken down into degrees, minutes of arc, and seconds of arc.
Declination readings south of the equator carry a minus sign (-) in front of the coordinate and those north of the
celestial equator are either blank (i.e., no designation) or preceded by a plus sign (+).

The celestial equivalent of longitude is called Right Ascension, or R.A. for short. Like the Earth's lines of longitude,
they run from pole to pole and are evenly spaced 15 degrees apart. Although the longitude lines are separated by an
angular distance, they are also a measure of time. Each line of longitude is one hour apart from the next. Since the
Earth rotates once every 24 hours, there are 24 lines total. As a result, the R.A. coordinates are marked off in units of
time. It begins with an arbitrary point in the constellation of Pisces designated as 0 hours, 0 minutes, 0 seconds. All
other points are designated by how far (i.e., how long) they lag behind this coordinate after it passes overhead moving
toward the west.

Figure 7-1

The celestial sphere seen from the outside showing R.A. and DEC.

27

s

MMoottiioonn ooff tthhee SSttaarrs

The daily motion of the Sun across the sky is familiar to even the most casual observer. This daily trek is not the Sun
moving as early astronomers thought, but the result of the Earth's rotation. The Earth's rotation also causes the stars to
do the same, scribing out a large circle as the Earth completes one rotation. The size of the circular path a star follows
depends on where it is in the sky. Stars near the celestial equator form the largest circles rising in the east and setting in
the west. Moving toward the north celestial pole, the point around which the stars in the northern hemisphere appear to
rotate, these circles become smaller. Stars in the mid-celestial latitudes rise in the northeast and set in the northwest.
Stars at high celestial latitudes are always above the horizon, and are said to be circumpolar because they never rise and
never set. You will never see the stars complete one circle because the sunlight during the day washes out the starlight.
However, part of this circular motion of stars in this region of the sky can be seen by setting up a camera on a tripod
and opening the shutter for a couple hours. The processed film will reveal semicircles that revolve around the pole.
(This description of stellar motions also applies to the southern hemisphere except all stars south of the celestial equator
move around the south celestial pole.)

All stars appear to rotate around the celestial poles. However, the appearance of this motion
varies depending on where you are looking in the sky. Near the north celestial pole the stars
scribe out recognizable circles centered on the pole (1). Stars near the celestial equator also
follow circular paths around the pole. But, the complete path is interrupted by the horizon.
These appear to rise in the east and set in the west (2). Looking toward the opposite pole, stars
curve or arc in the opposite direction scribing a circle around the opposite pole (3).

Figure 7-2

28

Warning!

)

PPoollaarr AAlliiggnnmmeenntt ((wwiitthh ooppttiioonnaall WWeeddggee)

Even though the NexStar can precisely track a celestial object while in the Alt-Az position, it is still necessary to align
the polar axis of the telescope (the fork arm) to the Earth's axis on rotation in order to attempt long exposure astro
photography. To do an accurate polar alignment, the NexStar requires an optional equatorial wedge (#93658) between
the telescope and a tripod. Celestron also offers a steel tripod with an attached wedge tilt plate (#93497). This allows
the telescope's tracking motors to rotate the telescope around the celestial pole, the same way as the stars. Without the
equatorial wedge, you would notice the stars in the eyepiece would slowly rotate around the center of the field of view.
Although this gradual rotation would go unnoticed when viewing with an eyepiece, it would be very noticeable on
film.

Polar alignment is the process by which the telescope's axis of rotation (called the polar axis) is aligned (made parallel)
with the Earth's axis of rotation. Once aligned, a telescope with a clock drive will track the stars as they move across
the sky. The result is that objects observed through the telescope appear stationary (i.e., they will not drift out of the
field of view). If not using the clock drive, all objects in the sky (day or night) will slowly drift out of the field. This
motion is caused by the Earth's rotation.

Remember, whenever attaching the NexStar to the NexStar tripod or wedge, always use the bolts that come with the
accessory. Never use bolts that thread more than 3/8" into the bottom of the NexStar base. Threading bolts more than
3/8" into the base will damage the internal gears.

Whether you are using your NexStar in the Alt-Az configuration or polar aligned, it will be necessary to locate where
north is and more specifically where the North Star is.

Definition

The polar axis is the axis around which the telescope rotates when moved in right ascension. This axis points
the same direction even when the telescope moves in right ascension and declination.

AAlliiggnniinngg tthhee NNeexxSSttaarr 44 oonn aa WWeeddggee

In order to do a star alignment while using the NexStar on an
equatorial wedge it will be necessary to alter some of the
alignment procedures when doing the AutoAlign. Before the
NexStar is attached to the wedge, slew the telescope so that
the tube is pointed straight up overhead (the tube should be
parallel to the fork arm). Attach the telescope to the wedge
and angle the wedge so that the NexStar's fork arm is
pointing towards Polaris. Move the tripod side to side and tilt
the wedge up and down until Polaris is aligned in the
StarPointer and visible in the eyepiece. Now recycle the
power on the NexStar and begin the AutoAlign procedure as
follows:

1. When the hand control asks you to point the tube

north and level, use the arrow keys to rotate the
telescope tube downward until the tube is
perpendicular (at 90º) with the fork arm.

2. Continue to enter the date and time as requested.

When asked to "choose location", you must scroll
down to the Enter Long / Lat option. Since the
telescope's fork arm is pointed at the celestial pole
(Polaris), you will need to enter location
information as if you were doing an Alt-Az
alignment from the North Pole. To accomplish
this, when asked for your locations latitude, input
the number +89º (-89º for observing in the southern
hemisphere). When asked for longitude, input the longitude for your current location. A list of longitudes
and latitudes can be obtained in most Atlases or on the Celestron web site. You will probably want to save
this location in the database if you will be observing often from an equatorial wedge.

This is how the telescope is to be set up for polar
alignment. The tube should be parallel to the
fork arm which should be pointed to Polaris.

Figure 7-3

29

3. Once complete the NexStar will automatically slew to the first alignment star. If the star that is chosen is in

the north, it may be below the horizon. If so, abort the slew by pressing any of the arrow direction buttons
before the telescope tube comes into contact with the base. Press the UNDO button to select an alignment
star that is above the horizon. Use the hand control to center the alignment star with the Star Pointer and
press ENTER, then center the star in the eyepiece and press ALIGN. Repeat this step with the second
alignment star. For complete AutoAlign procedures, see NexStar GT section of this manual.

4. Now that the NexStar is polar aligned switch the tracking mode to EQ North. This will turn off the altitude

motor and allow the Azimuth motor to track like a right ascension tracking motor. To switch to EQ North
tracking, press the MENU button and press ENTER at the Tracking Mode sub-menu. Use the scroll buttons
to select EQ North and press ENTER.

Photography with the NexStar 4

After looking at the night sky for a while you may want to try photographing it. In addition to the specific accessories
required for celestial photography, there is the need for a camera - but not just any camera. The camera does not have
to have many of the features offered on today's state-of-the-art equipment. For example, you don't need auto focus
capability or mirror lock up. Here are the mandatory features a camera needs for celestial photography. First, a “B”
setting which allows for time exposures. This excludes point and shoot cameras and limits the selection to SLR
cameras, the most common type of 35mm camera on the market today.

Second, the “B” or manual setting should NOT run off the battery. Many new electronic cameras use the battery to
keep the shutter open during time exposures. Once the batteries are drained, usually after a few minutes, the shutter
closes, whether you were finished with the exposure or not. Look for a camera that has a manual shutter when
operating in the time exposure mode. Olympus, Nikon, Minolta, Pentax, Canon and others have made such camera
bodies.

The camera must have interchangeable lenses so you can attach it to the telescope and so you can use a variety of
lenses for piggyback photography. If you can't find a new camera, you can purchase a used camera body that is not
100-percent functional. The light meter, for example, does not have to be operational since you will be determining the
exposure length manually.

You also need a cable release with a locking function to hold the shutter open while you do other things. Mechanical
and air release models are available.

AAttttaacchhiinngg aa CCaammeerraa ttoo tthhee NNeexxSSttaarr

The NexStar 4 has a special adaptor port located on the back of the rear cell to connect a 35mm camera body.
Attaching a camera to the NexStar requires the use of the optional T-adapter (#93635-A) and a T-ring specific to the
brand of camera being used. To attach the photographic
accessories:

1.

2. Thread the T-adapter securely onto the photo

3. Thread the T-ring onto the exposed end of the T-

4. Remove any lens from the body of your camera.

5. Attach the camera body to the T-ring by aligning

Before attempting photography through your NexStar make
sure that the flip mirror is in the "down" position. This will
allow the light path to go straight through the optical tube and
pass directly into the camera.

Remove the screw-on cover from the photo adaptor

port on the rear cell.

adapter port.

adapter.

the red dot on the side of the T-ring with the dot on the
camera body and twisting.

Camera Body

T-Ring

Figure 7-4 – NexStar with photographic Accessories

T-Adapter

30

Finding the North Celestial Pole

In each hemisphere, there is a point in the sky around which all the other stars appear to rotate. These points are called
the celestial poles and are named for the hemisphere in which they reside. For example, in the northern hemisphere all
stars move around the north celestial pole. When the telescope's polar axis is pointed at the celestial pole, it is parallel
to the Earth's rotational axis.

Many methods of polar alignment require that you know how to find the celestial
pole by identifying stars in the area. For those in the northern hemisphere, finding
the celestial pole is not too difficult. Fortunately, we have a naked eye star less than
a degree away. This star, Polaris, is the end star in the handle of the Little Dipper.
Since the Little Dipper (technically called Ursa Minor) is not one of the brightest
constellations in the sky, it may be difficult to locate from urban areas. If this is the
case, use the two end stars in the bowl of the Big Dipper (the pointer stars). Draw an
imaginary line through them toward the Little Dipper. They point to Polaris (see
Figure 7-5). The position of the Big Dipper changes during the year and throughout
the course of the night (see Figure 7-5). When the Big Dipper is low in the sky (i.e.,
near the horizon), it may be difficult to locate. During these times, look for
Cassiopeia (see Figure 7-6). Observers in the southern hemisphere are not as
fortunate as those in the northern hemisphere. The stars around the south celestial

Figure 7-5

The position of the Big

Dipper changes throughout

the year and the night.

pole are not nearly as bright as those around the north. The closest star that is
relatively bright is Sigma Octantis. This star is just within naked eye limit
(magnitude 5.5) and lies about 59 arc minutes from the pole.

Definition

The north celestial pole is the point in the northern hemisphere around which all stars

appear to rotate. The counterpart in the southern hemisphere is referred to as the south

celestial pole.

The two stars in the front of the bowl of the Big Dipper point to Polaris which is less than
one degree from the true (north) celestial pole. Cassiopeia, the “W” shaped constellation,
is on the opposite side of the pole from the Big Dipper. The North Celestial Pole (N.C.P.)
is marked by the “+” sign.

Figure 7-6

31

With your telescope set up, you are ready to use it for observing. This section covers visual observing hints for both
solar system and deep sky objects as well as general observing conditions which will affect your ability to observe.

n

OObbsseerrvviinngg tthhee MMoooon

Often, it is tempting to look at the Moon when it is full. At this time, the face we see is fully illuminated and its light
can be overpowering. In addition, little or no contrast can be seen during this phase.

filters. A yellow filter works well at improving contrast while a neutral density or polarizing filter will reduce
overall surface brightness and glare.

One of the best times to observe the Moon is during its partial phases
(around the time of first or third quarter). Long shadows reveal a great
amount of detail on the lunar surface. At low power you will be able to
see most of the lunar disk at one time. Change to higher power
(magnification) to focus in on a smaller area. Choose the lunar tracking
rate from the NexStar's MENU tracking rate options to keep the moon
centered in the eyepiece even at high magnifications.

LLuunnaarr OObbsseerrvviinngg HHiinnttss

To increase contrast and bring out detail on the lunar surface, use

•

s

OObbsseerrvviinngg tthhee PPllaanneetts

Other fascinating targets include the five naked eye planets. You can see Venus go through its lunar-like phases. Mars
can reveal a host of surface detail and one, if not both, of its polar caps. You will be able to see the cloud belts of
Jupiter and the great Red Spot (if it is visible at the time you are observing). In addition, you will also be able to see
the moons of Jupiter as they orbit the giant planet. Saturn, with its beautiful rings, is easily visible at moderate power.

PPllaanneettaarryy OObbsseerrvviinngg HHiinnttss

Remember that atmospheric conditions are usually the limiting

•

factor on how much planetary detail will be visible. So, avoid
observing the planets when they are low on the horizon or when
they are directly over a source of radiating heat, such as a rooftop or
chimney. See the "Seeing Conditions" section later in this section.
To increase contrast and bring out detail on the planetary surface,

•

try using Celestron eyepiece filters.

32

n

OObbsseerrvviinngg tthhee SSuun

Although overlooked by many amateur astronomers, solar observation is both rewarding and fun. However, because
the Sun is so bright, special precautions must be taken when observing our star so as not to damage your eyes or your
telescope.

Never project an image of the Sun through the telescope. Because of the folded optical design, tremendous heat
build-up will result inside the optical tube. This can damage the telescope and/or any accessories attached to the
telescope.

For safe solar viewing, use a solar filter that reduces the intensity of the Sun's light, making it safe to view. With
a filter you can see sunspots as they move across the solar disk and faculae, which are bright patches seen near
the Sun's edge.

SSoollaarr OObbsseerrvviinngg HHiinnttss

• The best time to observe the Sun is in the early morning or late afternoon when the air is cooler.

• To center the Sun without looking into the eyepiece, watch the shadow of the telescope tube until it forms a
circular shadow.

• To ensure accurate tracking, be sure to select solar tracking rate.

s

OObbsseerrvviinngg DDeeeepp SSkkyy OObbjjeecctts

Deep-sky objects are simply those objects outside the boundaries of our solar system. They include star clusters,
planetary nebulae, diffuse nebulae, double stars and other galaxies outside our own Milky Way. Most deep-sky objects
have a large angular size. Therefore, low-to-moderate power is all you need to see them. Visually, they are too faint to
reveal any of the color seen in long exposure photographs. Instead, they appear black and white. And, because of their
low surface brightness, they should be observed from a dark-sky location. Light pollution around large urban areas
washes out most nebulae making them difficult, if not impossible, to observe. Light Pollution Reduction filters help
reduce the background sky brightness, thus increasing contrast.

s

SSeeeeiinngg CCoonnddiittiioonns

Viewing conditions affect what you can see through your telescope during an observing session. Conditions include
transparency, sky illumination, and seeing. Understanding viewing conditions and the effect they have on observing
will help you get the most out of your telescope.

Transparency

Transparency is the clarity of the atmosphere which is affected by clouds, moisture, and other airborne particles. Thick
cumulus clouds are completely opaque while cirrus can be thin, allowing the light from the brightest stars through.
Hazy skies absorb more light than clear skies making fainter objects harder to see and reducing contrast on brighter
objects. Aerosols ejected into the upper atmosphere from volcanic eruptions also affect transparency. Ideal conditions
are when the night sky is inky black.

Sky Illumination

General sky brightening caused by the Moon, aurorae, natural airglow, and light pollution greatly affect transparency.
While not a problem for the brighter stars and planets, bright skies reduce the contrast of extended nebulae making
them difficult, if not impossible, to see. To maximize your observing, limit deep sky viewing to moonless nights far
from the light polluted skies found around major urban areas. LPR filters enhance deep sky viewing from light
polluted areas by blocking unwanted light while transmitting light from certain deep sky objects. You can, on the other
hand, observe planets and stars from light polluted areas or when the Moon is out.

33

Seeing

Seeing conditions refers to the stability of the atmosphere and directly affects the amount of fine detail seen in extended
objects. The air in our atmosphere acts as a lens which bends and distorts incoming light rays. The amount of bending
depends on air density. Varying temperature layers have different densities and, therefore, bend light differently. Light
rays from the same object arrive slightly displaced creating an imperfect or smeared image. These atmospheric
disturbances vary from time-to-time and place-to-place. The size of the air parcels compared to your aperture
determines the "seeing" quality. Under good seeing conditions, fine detail is visible on the brighter planets like Jupiter
and Mars, and stars are pinpoint images. Under poor seeing conditions, images are blurred and stars appear as blobs.

The conditions described here apply to both visual and photographic observations.

Figure 8-1
Seeing conditions directly affect image quality. These drawings represent a point
source (i.e., star) under bad seeing conditions (left) to excellent conditions (right).
Most often, seeing conditions produce images that lie some where between these two
extremes.

34

While your NexStar telescope requires little maintenance, there are a few things to remember that will ensure your telescope
performs at its best.

CCaarree aanndd CClleeaanniinngg ooff tthhee OOppttiiccss

Occasionally, dust and/or moisture may build up on the corrector plate of your telescope. Special care should be taken when
cleaning any instrument so as not to damage the optics.

If dust has built up on the corrector plate, remove it with a brush (made of camel’s hair) or a can of pressurized air. Spray at an
angle to the lens for approximately two to four seconds. Then, use an optical cleaning solution and white tissue paper to remove
any remaining debris. Apply the solution to the tissue and then apply the tissue paper to the lens. Low pressure strokes should
go from the center of the corrector to the outer portion.

You can use a commercially made lens cleaner or mix your own. A good cleaning solution is isopropyl alcohol mixed with
distilled water. The solution should be 60% isopropyl alcohol and 40% distilled water. Or, liquid dish soap diluted with water (a
couple of drops per one quart of water) can be used.

Occasionally, you may experience dew build-up on the corrector plate of your telescope during an observing session. If you want
to continue observing, the dew must be removed, either with a hair dryer (on low setting) or by pointing the telescope at the
ground until the dew has evaporated.

If moisture condenses on the inside of the corrector, remove the accessories from the rear cell of the telescope. Place the
telescope in a dust-free environment and point it down. This will remove the moisture from the telescope tube.

To minimize the need to clean your telescope, replace all lens covers once you have finished using it. Since the rear cell is NOT
sealed, the cover should be placed over the opening when not in use. This will prevent contaminants from entering the optical
tube.

Internal adjustments and cleaning should be done only by the Celestron repair department. If your telescope is in need of internal
cleaning, please call the factory for a return authorization number and price quote.

Do NOT rub in circles!

35

You will find that additional accessories enhance your viewing pleasure and expand the usefulness of your telescope. For
ease of reference, all the accessories are listed in alphabetical order.

Adapter, AC (#18770)

adapter attaches to any standard wall outlet.

Adapter, Car Battery (#18769) -

Carrying Case (#302080) -

completely lined with pick-n-pluck foam for a customized and secure fit to safely transport and store your scope and
accessories..

Like telescopes, eyepieces come in a variety of designs. Each design has its own advantages and

Eyepieces -

disadvantages. For the 1-1/4" barrel diameter there are four different eyepiece designs available.

Super Modified Achromatic (SMA) Eyepieces: 11/

•

The SMA design is an improved version of the Kellner eyepiece. SMA's are very good, economical, general purpose

eyepieces that deliver a wide apparent field, good color correction and an excellent image at the center of the field of view.
Celestron offers SMA eyepieces in 1-1/4" sizes in the following focal lengths: 6mm, 10mm, 12mm, 17mm and 25mm.

• Plössl

views across the entire field, even at the edges! In the 1-1/4" barrel diameter, they are available in the following focal
lengths: 3.6mm, 6mm, 8mm, 10mm, 13mm, 17mm, 25mm, 32mm and 40mm.

• Ultima -

field eyepieces. In the 1-1/4" barrel diameter, they are available in the following
focal lengths: 5mm, 7.5mm, 12.5mm, 18mm, 30mm, 35mm, and 42mm. These
eyepieces are all parfocal. The 35mm Ultima gives the widest possible field of
view with a 1-1/4" diagonal .

•

Lanthanum Eyepieces (LV Series)

in one of the field lenses of this new eyepiece. The Lanthanum glass reduces
aberrations to a minimum. All are fully multicoated and have an astounding 20mm
of eye relief — perfect for eyeglass wearers! In the 1-1/4" barrel diameter, they are
available in the following focal lengths: 2.5mm, 4mm, 5mm, 6mm, 9mm, 10mm,
12mm and 15mm. Celestron also offers the LV Zoom eyepiece (#3777) with a focal
length of 8mm to 24mm. It offers an apparent field of 40º at 24mm and 60º at 8mm.
Eye relief ranges from 15mm to 19mm

- Plössl eyepieces have a 4-element lens designed for low-to-high power observing. The Plössls offer razor sharp

Ultima is not really a design, but a trade name for our 5-element, wide

– Allows DC (battery) powered telescopes to be converted for use with 120 volt AC power. The

Celestron offers the Car Battery Adapter that allows you to run the NexStar drive off

an external power source. The adapter attaches to the cigarette lighter of your car,
truck, van, or motorcycle.

A Barlow lens is a negative lens that increases the focal length of a

Barlow Lens -

telescope. Used with any eyepiece, it doubles the magnification of that eyepiece.
Celestron offers two Barlow lens in the 1-1/4" size for the NexStar. The 2x Ultima
Barlow (#93506) is a compact triplet design that is fully multicoated for maximum
light transmission and parfocal when used with the Ultima eyepieces. Model #93507
is a compact achromatic Barlow lens that is under three inches long and weighs only
4 oz. It works very well

This case fits both the NexStar 4 and NexStar 5 and is made of sturdy ABS plastic. It is

- Lanthanum is a unique rare earth glass used

.

with all Celestron eyepieces.

"

4

36

Eyepiece Filters

filters that thread into the 1-1/4" oculars. Available individually are: #12 deep yellow, #21 orange, #25 red, #58 green,
#80A light blue, #96 neutral density - 25%T, #96 neutral density - 13%T, and polarizing. These and other filters are also
sold in sets.

and low pressure sodium vapor lights. In addition, they also block unwanted natural light (sky glow) caused by neutral
oxygen emission in our atmosphere. Celestron offers a model for 1-1/4" eyepieces (#94126A).

Hand Control, Upgrade (#93961) –

Combined with your telescope’s built-in slew motors, your NexStar will have the ability to automatically find all the
Messier objects, dozens of double stars and all the planets at a touch of a button. Hand control comes with built-in RS-232

For 20
For 30
For 40

Polarizing Filter Set (#93608) -

contrast between various objects. This is used primarily for terrestrial, lunar and planetary observing.

Sky Maps (#93722) -

night sky. You wouldn’t set off on a road trip without a road map, and you don’t need
to try to navigate the night sky without a map either. Even if you already know your
way around the major constellations, these maps can help you locate all kinds of
fascinating objects.

T-Adapter (#93635-A) -

SLR camera to the rear cell of your Celestron NexStar. This turns your NexStar into a
1300mm telephoto lens perfect for terrestrial photography and short exposure lunar and
filtered solar photography.

T-Ring -

do photography through the telescope. Each camera make (i.e., Minolta, Nikon, Pentax, etc.) has its own unique mount and
therefore, its own T-Ring. Celestron has 8 different models for 35mm cameras.

The T-Ring couples your 35mm SLR camera body to the T-Adapter. This accessory is mandatory if you want to

To enhance your visual observations of solar system objects, Celestron offers a wide range of colored

-

Night Vision Flashlight - (#93588) -

using two red LED's to preserve night vision better than red filters or other
devices. Brightness is adjustable. Operates on a single 9 volt battery (included).

Red Astro Lite – (#93590)

red cap to help preserve your night vision. Remove the red cap for normal
flashlight operation. Very compact size and handy key chain.

Light Pollution Reduction (LPR) Filter -

your views of deep sky astronomical objects when viewed from urban areas. LPR
Filters selectively reduce the transmission of certain wavelengths of light,
specifically those produced by artificial lights. This includes mercury and high

Plugs into your NexStar HC to give you instant access to over 4,000 celestial objects.

communication port capable of interfacing with popular astronomy software.

Moon Filter (#94119-A) -

reducing the brightness of the moon and improving contrast, so greater detail can be observed
on the lunar surface. The clear aperture is 21mm and the transmission is about 18%.

Planisphere (#93720) -

eye viewers to users of highly sophisticated telescopes. The Celestron Planisphere makes it
easy to locate stars for observing and is a great planet finder as well. A map of the night sky,
oriented by month and day, rotates within a depiction of the 24 hours of the day, to display
exactly which stars and planets will be visible at any given time. Ingeniously simple to use, yet
quite effective. Made of durable materials and coated for added protection. Celestron
Planispheres come in three different models, to match the latitude from which you’re observing:

to 40° of latitude #93720-30

°

to 50°of latitude #93720-40

°

to 60° of latitude #93720-50

°

The polarizing filter set limits the transmission of light to a specific plane, thus increasing

Celestron Sky Maps are the ideal teaching guide for learning the

T-Adapter (with additional T-Ring) allows you to attach your

Celestron’s Moon Filter is an economical eyepiece filter for

A simple and inexpensive tool for all levels of observers, from naked

– An economical squeeze-type flashlight fitted with a

Celestron’s premium model for astronomy,

These filters are designed to enhance

37

Tripod, NexStar

observing and photography. This steel field tripod (#93497) folds down to a
compact 8"x28". It is equipped with a built on wedge tilt plate for quick
equatorial use and astrophotography. It has a metal center brace and accessory
tray for added stability

Vibration Suppression Pads (#93503) -

and tripod feet of your telescope. They reduce the amplitude and vibration
time of your telescope when shaken by the wind or an accidental bump. This
accessory is a must for long exposure prime focus photography.

A full description of all Celestron accessories can be found in the Celestron Accessory Catalog (#93685).

- A stable tripod is a must for serious astronomical

.

These pads rest between the ground

38

Appendix A - Technical Specifications

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Design Maksutov-Cassegrain Catadioptric
Aperture 4 inches (102mm)
Focal Length 52 inches (1325mm)
F/ratio of the Optical System 13
Primary Mirror: Diameter
Coatings
Secondary Mirror Spot Size
Secondary Obstruction
Corrector Plate: Material
Coatings
Highest Useful Magnification 240x ( ~ 6mm eyepiece)
Lowest Useful Magnification (7mm exit pupil) 15x ( ~ 80mm eyepiece)
Resolution: Rayleigh Criterion
Dawes Limit
Photographic Resolution 140 lines/mm
Light Gathering Power 212x unaided eye
Near Focus standard eyepiece or camera ~ 20 feet
Field of View: Standard Eyepiece
: 35mm Camera
Linear Field of View (at 1000 yds) 52.5 feet
Magnification: Standard Eyepiece
: Camera
Optical Tube Length 13.5 inches
Weight of Telescope 11 Lbs.

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Minimum
Batteries Required 8 AA Alkaline
Power Supply Requirements 12 VDC-750 mA (Tip positive)

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Resolution
Slew speeds Nine slew speeds: 4º /sec, 2º /sec, 1º/sec, .5/sec, 32x, 16x, 8x, 4x, 2x
Hand Control

Fork Arm Cast aluminum, with integrated hand control receptacle

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Software Precision 16 bit, 20 arc sec. calculations
Ports RS-232 communication port on hand control
Tracking Rates Sidereal, Solar, Lunar and King
Tracking Modes Alt-Az, EQ North & EQ South
Alignment Procedures AutoAlign (2-star alignment)
Database 25 user defined programmable object.

Total Object Database 4,033

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Multi-layer coating process

1.25"

34.4% by diameter; 11% by area
BK-7 Optical Glass
A-R Coatings both sides

1.36 arc seconds

1.14 arc seconds

1.0º

1.51º x 1.04º

55x
27x

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12 V DC Nominal
18 V DC Max.
8 V DC Min.

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DC Servo motors with encoders, both axes
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Double line, 16 character Liquid Crystal Display
19 fiber optic backlit LED buttons

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Enhanced information on over 100 objects

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A

-

Absolute magnitude The apparent magnitude that a star would have if it were observed from a standard distance of 10

parsecs, or 32.6 light-years. The absolute magnitude of the Sun is 4.8. at a distance of 10 parsecs, it
would just be visible on Earth on a clear moonless night away from surface light.

Airy disk The apparent size of a star's disk produced even by a perfect optical system. Since the star can never

be focused perfectly, 84 per cent of the light will concentrate into a single disk, and 16 per cent into
a system of surrounding rings.

Alt-Azimuth Mounting A telescope mounting using two independent rotation axis allowing movement of the instrument in

Altitude and Azimuth.

Altitude In astronomy, the altitude of a celestial object is its Angular Distance above or below the celestial

horizon.

Aperture the diameter of a telescope's primary lens or mirror; the larger the aperture, the greater the

telescope's light-gathering power.

Apparent Magnitude A measure of the relative brightness of a star or other celestial object as perceived by an observer on

Earth.

Arcminute A unit of angular size equal to 1/60 of a degree.
Arcsecond A unit of angular size equal to 1/3,600 of a degree (or 1/60 of an arcminute).
Asterism A small unofficial grouping of stars in the night sky.
Asteroid A small, rocky body that orbits a star.
Astrology The pseudoscientific belief that the positions of stars and planets exert an influence on human

affairs; astrology has nothing in common with astronomy

Astronomical unit (AU) The distance between the Earth and the Sun. It is equal to 149,597,900 km., usually rounded off to

150,000,000 km.

Aurora The emission of light when charged particles from the solar wind slams into and excites atoms and

molecules in a planet's upper atmosphere.

Azimuth The angular distance of an object eastwards along the horizon, measured from due north, between

the astronomical meridian (the vertical line passing through the center of the sky and the north and
south points on the horizon) and the vertical line containing the celestial body whose position is to
be measured. .

B

-

Binary Stars Binary (Double) stars are pairs of stars that, because of their mutual gravitational attraction, orbit

around a common Center of Mass. If a group of three or more stars revolve around one another, it is
called a multiple system. It is believed that approximately 50 percent of all stars belong to binary or
multiple systems. Systems with individual components that can be seen separately by a telescope are
called visual binaries or visual multiples. The nearest "star" to our solar system, Alpha Centauri, is
actually our nearest example of a multiple star system, it consists of three stars, two very similar to
our Sun and one dim, small, red star orbiting around one another.

C

-

Celestial Equator The projection of the Earth's equator on to the celestial sphere. It divides the sky into two equal

hemispheres.

Celestial pole The imaginary projection of Earth's rotational axis north or south pole onto the celestial sphere.
Celestial Sphere An imaginary sphere surrounding the Earth, concentric with the Earth's center.
Collimation The act of putting a telescope's optics into perfect alignment.

D

-

Declination (DEC) The angular distance of a celestial body north or south of the celestial equator. It may be said to

correspond to latitude on the surface of the Earth.

E -
Ecliptic The projection of the Earth's orbit on to the celestial sphere. It may also be defined as "the apparent

yearly path of the Sun against the stars".

Equatorial mount A telescope mounting in which the instrument is set upon an axis which is parallel to the axis of the

Earth; the angle of the axis must be equal to the observer's latitude.

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F -

Focal length The distance between a lens (or mirror) and the point at which the image of an object at infinity is

brought to focus. The focal length divided by the aperture of the mirror or lens is termed the focal
ratio.

J

-

Jovian Planets Any of the four gas giant planets that are at a greater distance form the sun than the terrestrial

planets.

K

-

Kuiper Belt A region beyond the orbit of Neptune extending to about 1000 AU which is a source of many short

period comets.

L

-

Light-Year (ly) A light-year is the distance light traverses in a vacuum in one year at the speed of 299,792 km/ sec.

With 31,557,600 seconds in a year, the light-year equals a distance of 9.46 X 1 trillion km (5.87 X 1
trillion mi).

M

-

Magnitude Magnitude is a measure of the brightness of a celestial body. The brightest stars are assigned

magnitude 1 and those increasingly fainter from 2 down to magnitude 5. The faintest star that can be
seen without a telescope is about magnitude 6. Each magnitude step corresponds to a ratio of 2.5 in
brightness. Thus a star of magnitude 1 is 2.5 times brighter than a star of magnitude 2, and 100 times
brighter than a magnitude 5 star. The brightest star, Sirius, has an apparent magnitude of -1.6, the
full moon is -12.7, and the Sun's brightness, expressed on a magnitude scale, is -26.78. The zero
point of the apparent magnitude scale is arbitrary.

Meridian A reference line in the sky that starts at the North celestial pole and ends at the South celestial pole

and passes through the zenith. If you are facing South, the meridian starts from your Southern
horizon and passes directly overhead to the North celestial pole.

Messier A French astronomer in the late 1700’s who was primarily looking for comets. Comets are hazy

diffuse objects and so Messier cataloged objects that were not comets to help his search. This
catalog became the Messier Catalog, M1 through M110.

N

-
Nebula Interstellar cloud of gas and dust. Also refers to any celestial object that has a cloudy appearance.
North Celestial Pole The point in the Northern hemisphere around which all the stars appear to rotate. This is caused by

the fact that the Earth is rotating on an axis that passes through the North and South celestial poles.
The star Polaris lies less than a degree from this point and is therefore referred to as the "Pole Star".

Nova Although Latin for "new" it denotes a star that suddenly becomes explosively bright at the end of its

life cycle.

O

-
Open Cluster One of the groupings of stars that are concentrated along the plane of the Milky Way. Most have an

asymmetrical appearance and are loosely assembled. They contain from a dozen to many hundreds
of stars.

P

-

Parallax Parallax is the difference in the apparent position of an object against a background when viewed by

an observer from two different locations. These positions and the actual position of the object form a
triangle from which the apex angle (the parallax) and the distance of the object can be determined if
the length of the baseline between the observing positions is known and the angular direction of the
object from each position at the ends of the baseline has been measured. The traditional method in
astronomy of determining the distance to a celestial object is to measure its parallax.

Parfocal Refers to a group of eyepieces that all require the same distance from the focal plane of the

telescope to be in focus. This means when you focus one parfocal eyepiece all the other parfocal
eyepieces, in a particular line of eyepieces, will be in focus.

Parsec The distance at which a star would show parallax of one second of arc. It is equal to 3.26 light-years,

206,265 astronomical units, or 30,8000,000,000,000 km. (Apart from the Sun, no star lies within
one parsec of us.)

Point Source An object which cannot be resolved into an image because it to too far away or too small is

considered a point source. A planet is far away but it can be resolved as a disk. Most stars cannot
be resolved as disks, they are too far away.

R

-
Reflector A telescope in which the light is collected by means of a mirror.

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Resolution The minimum detectable angle an optical system can detect. Because of diffraction, there is a limit

to the minimum angle, resolution. The larger the aperture, the better the resolution.

Right Ascension: (RA) The angular distance of a celestial object measured in hours, minutes, and seconds along the

Celestial Equator eastward from the Vernal Equinox.

S

-

Sidereal Rate This is the angular speed at which the Earth is rotating. Telescope tracking motors drive the

telescope at this rate. The rate is 15 arc seconds per second or 15 degrees per hour.

T

-

Terminator The boundary line between the light and dark portion of the moon or a planet.

U

-
Universe The totality of astronomical things, events, relations and energies capable of being described

objectively.

V

-
Variable Star A star whose brightness varies over time due to either inherent properties of the star or something

eclipsing or obscuring the brightness of the star.

W

-
Waning Moon The period of the moon's cycle between full and new, when its illuminated portion is decreasing.
Waxing Moon The period of the moon's cycle between new and full, when its illuminated portion is increasing.

Z

-

Zenith The point on the Celestial Sphere directly above the observer.

Zodiac The zodiac is the portion of the Celestial Sphere that lies within 8 degrees on either side of the

Ecliptic. The apparent paths of the Sun, the Moon, and the planets, with the exception of some
portions of the path of Pluto, lie within this band. Twelve divisions, or signs, each 30 degrees in
width, comprise the zodiac. These signs coincided with the zodiacal constellations about 2,000 years
ago. Because of the Precession of the Earth's axis, the Vernal Equinox has moved westward by
about 30 degrees since that time; the signs have moved with it and thus no longer coincide with the
constellations.

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CELESTRON ONE YEAR WARRANTY

A. Celestron International (CI) warrants this telescope to be free from defects in materials and workmanship for one year. CI will

repair or replace such product or part thereof which, upon inspection by CI, is found to be defective in materials or
workmanship. As a condition to the obligation of CI to repair or replace such product, the product must be returned to CI
together with proof-of-purchase satisfactory to CI.

B. The Proper Return Authorization Number must be obtained from CI in advance of return. Call Celestron at [phone] to

receive the number to be displayed on the outside of your shipping container.

All returns must be accompanied by a written statement setting forth the name, address, and daytime telephone number of the
owner, together with a brief description of any claimed defects. Parts or product for which replacement is made shall become
the property of CI.

The customer shall be responsible for all costs of transportation and insurance, both to and from the factory of CI, and
shall be required to prepay such costs.

CI shall use reasonable efforts to repair or replace any telescope covered by this warranty within thirty days of receipt. In the
event repair or replacement shall require more than thirty days, CI shall notify the customer accordingly. CI reserves the right to
replace any product which has been discontinued from its product line with a new product of comparable value and function.

This warranty shall be void and of no force of effect in the event a covered product has been modified in design or
function, or subjected to abuse, misuse, mishandling or unauthorized repair. Further, product malfunction or
deterioration due to normal wear is not covered by this warranty.

CI DISCLAIMS ANY WARRANTIES, EXPRESS OR IMPLIED, WHETHER OF MERCHANTABILITY OF FITNESS FOR
A PARTICULAR USE, EXCEPT AS EXPRESSLY SET FORTH HEREIN.

THE SOLE OBLIGATION OF CI UNDER THIS LIMITED WARRANTY SHALL BE TO REPAIR OR REPLACE THE
COVERED PRODUCT, IN ACCORDANCE WITH THE TERMS SET FORTH HEREIN. CI EXPRESSLY DISCLAIMS
ANY LOST PROFITS, GENERAL, SPECIAL, INDIRECT OR CONSEQUENTIAL DAMAGES WHICH MAY RESULT
FROM BREACH OF ANY WARRANTY, OR ARISING OUT OF THE USE OR INABILITY TO USE ANY CI PRODUCT.
ANY WARRANTIES WHICH ARE IMPLIED AND WHICH CANNOT BE DISCLAIMED SHALL BE LIMITED IN
DURATION TO A TERM OF ONE YEAR FROM THE DATE OF ORIGINAL RETAIL PURCHASE.

Some states do not allow the exclusion or limitation of incidental or consequential damages or limitation on how long an implied
warranty lasts, so the above limitations and exclusions may not apply to you.

This warranty gives you specific legal rights, and you may also have other rights which vary from state to state.

CI reserves the right to modify or discontinue, without prior notice to you, any model or style telescope.

If warranty problems arise, or if you need assistance in using your telescope contact:

Celestron International
Customer Service Department
2835 Columbia Street
Torrance, CA 90503

Tel. [phone]
Fax. [phone]
Monday-Friday 8AM-4PM PST

This warranty supersedes all other product warranties.

NOTE: This warranty is valid to U.S.A. and Canadian customers who have purchased this product from an Authorized
CI Dealer in the U.S.A. or Canada. Warranty outside the U.S.A. and Canada is valid only to customers who
purchased from a CI International Distributor or Authorized CI Dealer in the specific country and please contact
them for any warranty service.

Celestron International
2835 Columbia Street
Torrance, CA 90503
Tel. [phone]
Fax. [phone]
Web site at http//www.celestron.com

Copyright 2000 Celestron International
All rights reserved.

(Products or instructions may change
without notice or obligation.)

This device complies with Part 15 of the FCC Rule. Operation is subject to the following
two conditions: 1) This device may not cause harmful interference, and 2) This device
must accept any interference received, including interference that may cause undesired
operations.

#11041-I
Printed in China
$10.00
10-00

ADDENDUM TO NEXSTAR 4

TELESCOPE MANUAL

This document contains useful information about your NexStar 4 telescope that may not have
been included in your instruction manual at the time of printing. Listed below is information
regarding the utility features described under the hand control section of the manual. Please refer
to this addendum when using your NexStar 4 hand control.

Demo and Approach Length

quality control purposes and although they may appear on the hand control display they can not
be accessed by the user.

Light Control

and LCD display for daytime use and to help preserve your night vision. This feature is not
activated on the NexStar 4 model.

Model Select –

select your NexStar from a list of different models. If for some reason the incorrect model was
selected, the
settings.

Model Select

The
ratio for your individual NexStar model. For best possible pointing accuracy, this numeric gear
ratio should be entered into the hand control should you ever need to re-select the telescope
model. To enter the custom encoder-gear ratio for your NexStar model, follow the steps below:

1. When the hand control is turned-on, the display will read NexStar Ready, press the UNDO

button to by-pass the AutoAlign procedure.

2. Press the MENU button and use the Up and Down scroll keys until

on the screen, and press ENTER.

3. Use the Up and Down scroll keys to select

4. The display will read Azm = ??????? . For the NexStar 4 model, enter the number 1059334

and press ENTER. Now enter the same number for altitude as you did for azimuth, Alt =

1059334 and press ENTER.

5. The hand control will now say Recycle Power. Re-start the power to the telescope to save the

changes.

The telescope will now recognize your NexStar model as long as the custom setting is not
changed.

– This feature allows some NexStar models to turn off both the red key pad light

The first time the NexStar is powered on, the hand control display allows you to

Model Select

feature has a

-

These features are only used at the factory as diagnostic tools for

utility feature allows you to reset the hand control to its factory default

Custom

option that allows you to enter the exact encoder-gear

Custom

Model Select

and press ENTER.

Celestron International
Technical Support Department
2835 Columbia Street
Torrance, CA 90503
310-328-9560
310-212-5835 Fax
Monday – Friday 8am-4pm PST

is displayed

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