Celestron Nexstar Hc Users Manual Warning

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

WARNING.................................................................................................................................................... 4

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

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

ASSEMBLING THE NEXSTAR........................................................................................................................ 8

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

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

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

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

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

THE HAND CONTROL ................................................................................................................................12

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

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

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

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

HAND CONTROL OPERATION .................................................................................................................... 16

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

OBJECT CATALOG ..................................................................................................................................... 18

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

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

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

DIRECTION BUTTONS ................................................................................................................................19

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

SETUP PROCEDURES.................................................................................................................................. 20

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

UTILITY FEATURES ................................................................................................................................... 22

Cord Wrap.......................................................................................................................................... 22

Anti-backlash ..................................................................................................................................... 22

Model Select....................................................................................................................................... 22

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

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

IMAGE ORIENTATION ................................................................................................................................24

FOCUSING ................................................................................................................................................. 25

CALCULATING MAGNIFICATION................................................................................................................ 25

DETERMINING FIELD OF VIEW .................................................................................................................. 25

GENERAL OBSERVING HINTS .................................................................................................................... 26

ASTRONOMY BASICS................................................................................................................................. 27

THE CELESTIAL COORDINATE SYSTEM ..................................................................................................... 27

MOTION OF THE STARS ............................................................................................................................. 28

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POLAR ALIGNMENT (WITH OPTIONAL WEDGE) ......................................................................................... 29

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

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

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

OBSERVING THE MOON ............................................................................................................................. 32

OBSERVING THE PLANETS ......................................................................................................................... 32

OBSERVING THE SUN................................................................................................................................. 33

OBSERVING DEEP SKY OBJECTS ............................................................................................................... 33

SEEING CONDITIONS ................................................................................................................................. 33

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

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

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

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

CARE AND CLEANING OF THE OPTICS ....................................................................................................... 35

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

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

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

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

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

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Congratulations on your purchase of the Celestron NexStar! The NexStar ushers in a whole new generation of computer

automated technology. Simple and friendly to use, the NexStar is up and running after locating just two alignment stars.

It’s the perfect combination of power and portability. If you are new to astronomy, you may wish to start off by using the

NexStar's built-in Sky Tour feature, which commands the NexStar to find the most interesting objects in the sky and

automatically slews to each one. Or if you are an experienced amateur, you will appreciate the comprehensive database of

over 4,000 objects, including customized lists of all the best deep-sky objects, bright double stars and variable stars. No

matter at what level you are starting out, the NexStar will unfold for you and your friends all the wonders of the Universe.

Some of the many standard features of the NexStar include:

• Incredible 4°/second slew speed.

• Fully enclosed motors and optical encoders for position location.

• Integrated hand controller – built into the side of the fork arm.

• Storage for programmable user defined objects; and

Many other high performance features!

The NexStar’s deluxe features 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.

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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 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.

Remove the NexStar from its packaging and place

the base on a sturdy, level surface. Remove the

accessories from their individual boxes.

Once powered on, the display will read NexStar Ready.

Press ENTER to AutoAlign the NexStar. The hand control

display will ask you to move the telescope tube so that it is

level with the ground and facing the north horizon. Use

the UP and Down arrow buttons to position the telescope

North and level. (See Astronomy Basics for help on finding

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.

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Focuser Knob

StarPointer Eyepiece

Flip Mirror

Battery Compartment

Cover

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Input the necessary date and time information as

instructed by the hand control. Press ENTER after

each entry. The NexStar will also ask for time zone

and location information. Use the UP and Down scroll

buttons to select from the various options, pressing

ENTER after each selection. (See Hand Control

section for detailed ali

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Up and Down

Scroll Buttons

Direction

Buttons

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The NexStar will automatically pick an alignment star and slew

the telescope close to that star. Once there, the display will as

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you to use the arrow buttons to aim the Star Pointer at the star. I

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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".

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.

TOUR Button

Object List

Button

Catalog Keys

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Alignment Star

Star Pointer Finderscope

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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

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The NexStar 4 comes completely pre-assembled and can be operational in a matter of minutes. The NexStar is conveniently

packaged in one reusable shipping carton that contains all of the following accessories:

• 25mm SMA Eyepiece – 1¼"

• Star Pointer Finderscope and Mounting Bracket

• The Sky® for Celestron Astronomy Software

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Start by removing the telescope from its shipping carton and setting the round base on a flat table or surface. It is best to

carry the telescope by holding it from the lower portion of the fork arm and from the bottom of the base. Remove all of the

accessories from their individual boxes. Remember to save all of the containers so that they can be used to transport the

telescope. Before the batteries can be installed, the telescope tube should be positioned horizontal to the ground. To do this,

gently rotate the front of the tube upwards until it is level with the ground.

Powering the NexStar

The NexStar can be powered by eight AA batteries (not included), an optional 12v AC adapter or an optional car battery

adapter. The battery compartment is located in the center of the telescope's base (see figure 3-1).

To power the NexStar with batteries:

1. Remove the battery cover from the center of the base by

gently lifting up on the round portion of the cover.

2. Insert the batteries into the battery compartment of the base.

3. Reattach the battery compartment door by gently pushing

down on the cover until it snaps into place.

4. Turn on the power to the NexStar by flipping the switch,

located at the base of the fork arm, to the "On" position.

Battery Compartment

Cover

Figure 3-1: The NexStar 4 Battery Compartment

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The Hand Control

The hand control is located on the side of the fork arm and can be removed and used remotely or used while attached to the

fork. The hand control attaches to the fork arm by resting on two posts, located on the bottom of the hand control cradle,

and a clip inside the fork arm. To remove the hand control from the fork arm cradle, gently lift the hand control upwards

and pull out. To return the hand control into the fork arm, lower the hand control into the cradle so that the two holes in the

bottom of the hand control go over the posts on the bottom of the cradle, and the opening in the back of the hand control

slides over the clip inside the fork arm.

Once the telescope is powered up, the hand control can be used to move the optical tube in altitude (up and down) and

azimuth (side to side).

• 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).

Figure 3-2 – The Rear Cell with Visual Accessories

Focuser Knob

StarPointer Eyepiece

Flip Mirror Control

Diagonal

Barrel

Note:

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The Star Pointer Finderscope

The Star Pointer is the quickest and easiest way to point your telescope exactly at a desired object in the sky. It's like having

a laser pointer that you can shine directly onto the night sky. The Star Pointer is a zero magnification pointing tool that uses

a coated glass window to superimpose the image of a small red dot onto the night sky. While keeping both eyes open when

looking through the Star Pointer, simply move your telescope until the red dot, seen through the Star Pointer, merges with

the object as seen with your unaided eye. The red dot is produced by a light-emitting diode (LED); it is not a laser beam and

will not damage the glass window or your eye. The Star Pointer comes equipped with a variable brightness control, two axes

alignment control and a quick-release dovetail mounting bracket. Before the Star Pointer is ready to be used, it must be

attached to the telescope tube and properly aligned:

Star Pointer Installation

1. 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.

Azimuth Control

Knob

Dovetail Mounting Bracket

Mounting Track

ON/OFF

Variable Brightness

Control

Altitude Control

Knob

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

Glass Window

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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 . Remember to remove the plastic cover over the battery,

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

LED.

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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).

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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. Star Key Activation Light: Indicates that the Star button has been pressed and the utility functions on the hand

control are active.

2. Direction Buttons: Allows complete control of the NexStar in any direction. Use the direction keys to move the

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

3. 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.

Figure 4-1

The NexStar HC Hand Control

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4. Star Key: Gives the user access to the utility functions of the hand control, such as changing the direction of the arrow

keys and backlash compensation.

5. Hand Control Slew Rate Indicator Lights: Displays the speed at which the telescope will move when each direction

button is pressed.

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: 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:

1. Press the

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

RATE button on the hand control.

3. Press the

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

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

how long it takes for a star to move in the eyepiece when the hand control arrow buttons are pressed (especially

when changing directions). The NexStar's anti-backlash 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:

1. Press the

STAR key on the hand control.

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.

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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

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

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 CD-

ROM 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.

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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:

1. Liquid Crystal Display (LCD) Window: Has a dual-line, 16 character display screen that is backlit for comfortable

viewing of telescope information and scrolling text.

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

3. Direction Keys: Allows complete control of the NexStar in any direction. Use the direction keys to move the

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

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:

Figure 5-1

The NexStar Hand Control

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Messier – Complete list of all Messier objects.

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

Caldwell – A combination of the best NGC and IC objects.

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

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

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

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

Alignment Stars Common name listing of the brightest stars in the sky.

Named Objects Alphabetical listing of over 50 of the most popular deep

sky objects.

Double Stars Numeric-alphabetical listing of the most visually stunning

double, triple and quadruple stars in the sky.

Variable Stars Select list of the brightest variable stars with the shortest

period of changing magnitude.

Asterisms A unique list of some of the most recognizable star

patterns in the sky.

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

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

NexStar to those objects.

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

8. Undo: Undo will take you out of the current menu and display the previous level of the menu path. Press Undo

repeatedly to get back to a main menu or use it to erase data entered by mistake.

9. Menu: Displays the many setup and utilities functions such as tracking rate and user defined objects and many

others.

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

sub-menus.

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

12. RS-232 Jack: Allows you to interface with a computer and control the NexStar remotely.

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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 Select Model

Select ModelSelect Model

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

through the different NexStar models. Press ENTER when your NexStar model is displayed on the hand control. This

information will be retained for future use and will not be displayed again. Note: your hand control may have been pre

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 NexStar Ready

NexStar Ready NexStar Ready

NexStar Ready –

––

– Custom

Custom Custom

Custom,

and you can

simply press ENTER and continue to follow the Auto Align procedures below.

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.

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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

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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:

Date - Enter the month, day and year of your observing session. The display will read: mm/dd/yy

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

• 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 MethodSelect Method

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

Choose Choose

Choose

City

CityCity

City if it is not already displayed, and press ENTER.

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 United States

United StatesUnited States

United States is displayed. For international locations, use the Up or

Down scroll key to select International

InternationalInternational

International and press ENTER.

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 DefinedUser Defined

User Defined instead of the Choose City

Choose CityChoose City

Choose City. When User Defined

User DefinedUser Defined

User 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 SuccessfulAlignment Successful

Alignment Successful,

and you are now ready to find your first object.

If the wrong star was centered and aligned to, the NexStar display will read 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 re-

center 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.

Trouble

Shooting

18

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).

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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.

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Selecting an Object

Now that the telescope is properly aligned, you can choose an object from any of the catalogs in the NexStar's extensive

database. The hand control has a key (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:

More

Information

19

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

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:

• 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.

2. Press the ENTER Key. This will automatically slew the telescope to the coordinates of the object.

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.

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.

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The NexStar has four direction buttons in the center of the hand control which control the telescope motion in altitude (up

and down) and azimuth (left and right). The telescope can be controlled at nine different speed rates.

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.

Observing

Tip

20

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

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The NexStar contains many user defined setup functions designed to give the user control over the telescope's many

advanced features. All of the setup and utility features can be accessed by pressing the MENU key and scrolling through the

options:

Tracking Mode Once the NexStar is aligned the tracking motors will automatically turn on and begin

tracking the sky. However, the tracking can be turned off for terrestrial use:

Alt-Az This is the default tracking rate and is used when the telescope is placed on

a flat surface or tripod without the use of an equatorial wedge. The

telescope must be aligned with two stars before it can track in Alt-Az.

EQ North Used to track the sky when the telescope is polar aligned using an

equatorial wedge in the Northern Hemisphere.

EQ South Used to track the sky when the telescope is polar aligned using an

equatorial wedge in the Southern Hemisphere.

Off When using the telescope for terrestrial (land) observation, the tracking

can be turned off so that the telescope never moves.

Tracking Rate In addition to being able to move the telescope with the hand control buttons, the NexStar

will continually track a celestial object as it moves across the night sky. The tracking rate

can be changed depending on what type of object is being observed:

Nine available slew speeds

21

Sidereal This rate compensates for the rotation of the earth by moving the

telescope at the same rate as the rotation of the earth, but in the opposite

direction. When the telescope is polar aligned, this can be accomplished

by moving the telescope in Right Ascension only. When mounted in Alt-

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

declination.

Lunar Used for tracking the moon when observing the lunar landscape.

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

King 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.

User Objects

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: The NexStar stores celestial objects to its database by saving its right ascension and

declination in the sky. This way the same object can be found each time the telescope is

aligned. Once a desired object is centered in the eyepiece, simply scroll to the "Save Sky

Save Sky Save Sky

Save Sky

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Obj

bj bj

bj "

" "

" command and press 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.

Save Land Object: The NexStar can also be used as a spotting scope on terrestrial objects. Fixed land objects

can be stored by saving their altitude and azimuth relative to the location of the telescope at

the time of observing. Since these objects are relative to the location of the telescope, they

are only valid for that exact location. To save land objects, once again center the desired

object in the eyepiece. Scroll down to the "Save Land Obj

Save Land ObjSave Land Obj

Save Land Obj" command and press

ENTER. The display will ask you to enter a number between 1-9 to identify the object. Press

ENTER again to save this object to the database.

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

GoToGoTo

GoTo

Sky

SkySky

Sky Obj

Obj Obj

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

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

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

GoToGoTo

GoTo

Land

LandLand

Land Obj

Obj Obj

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

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

To replace the contents of any of the user defined objects, simply save a new object using one of the existing identification

numbers; NexStar will replace the previous user defined object with the current one.

Get RA/DEC - Displays the right ascension and declination for the current position of the telescope.

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

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

22

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

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

described above.

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

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

by how long it takes for a star to move in the eyepiece when the hand control arrow buttons are pressed (especially when

changing directions). The NexStar's anti-backlash features allows the user to compensate for backlash by inputting a value

which quickly rewinds the motors just enough to eliminate the play between gears. The amount of compensation needed

depends on the slewing rate selected; the slower the slewing rate the longer it will take for the star to appear to move in the

eyepiece. Therefore, the anti-backlash compensation will have to be set higher. You will need to experiment with

different values; a value between 20 and 50 is usually best for most visual observing, whereas a higher value may be

necessary for photographic guiding.

To set the anti-backlash value, scroll down to the Azm Backlash

Azm BacklashAzm Backlash

Azm Backlash or Alt Backlash

Alt BacklashAlt Backlash

Alt Backlash and press ENTER. Enter a value

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

list of different models. If for some reason the incorrect model was selected, 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. NOTE: If your hand control has been pre-set at the

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.

Observing

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ALT-AZ

EQ NORTH

EQ SO UTH

OFF

TRACKING MODE

SIDEREAL

SOLAR

LUNAR

KING

TRACKING RATE

GET ALT-AZ

GET RA-DEC

GOTO ALT-AZ

GOTO RA-DEC

GOTO SKY OBJECT

GOTO LAND OBJECT

SAVE SKY OBJECT

SAVE LAND OBJECT

USER OBJECTS

POWER CORD

BATTERY

CORD WRAP

AZM BACKLASH

ALT BACKLASH

Custom

NexStar 60

NexStar 70

NexStar 80

NexStar 114

NexStar 4"

MODEL SELECT

MENU

Choose City

Choose State

UNITED STATES

Choose City

Choose Country

INTER NATIO NAL

CHOOSE CITY

CHOOSE CITY

SELECT LOCATION

USER DEFINED

ENTER LONG / LAT

SELECT METHOD

ENTER TIME

ENTER DATE

NORTH & LEVEL

AUTO ALIGN

ALIGNM ENT

NAMED STARS

NAMED OBJECTS

DOUBLE STARS

VARIABLE STARS

ASTERISMS

TOUR

PLANETS

LIST

NexStar Ready

NexStar Menu Tree:

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

command functions

24

Fig 6-2a - Actual image

orientation as seen with the

unaided eye

Fig 6-2b - Reversed from left to

right, as viewed through the

eyepiece

Figure 6-1

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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 Maksutov-

Cassegrain 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.

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.

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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.

25

Figure 6-3

The emblem on the end of

the focus knob shows the

correct rotational direction

for focusing the NexStar.

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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.

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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.

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.

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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).

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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.

27

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.

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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.

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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.)

Figure 7-2

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).

29

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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.

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.

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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.

Definition

Figure 7-3

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.

Warning!

30

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.

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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. Remove the screw-on cover from the photo adaptor

port on the rear cell.

2. Thread the T-adapter securely onto the photo

adapter port.

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

adapter.

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

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

the red dot on the side of the T-ring with the dot on the

camera body and twisting.

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.

Figure 7-4 – NexStar with photographic Accessories

Camera Body

T-Ring T-Ada

p

ter

31

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

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.

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.

Definition

Figure 7-5

The position of the Big

Dipper changes throughout

the year and the night.

Figure 7-6

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.

32

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.

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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.

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.

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

filters. A yellow filter works well at improving contrast while a neutral density or polarizing filter will reduce

overall surface brightness and glare.

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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.

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• 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.

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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.

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• 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.

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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.

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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.

34

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.

35

While your NexStar telescope requires little maintenance, there are a few things to remember that will ensure your telescope

performs at its best.

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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. Do NOT rub in circles!

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.

36

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

adapter attaches to any standard wall outlet.

Adapter, Car Battery (#18769) - 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.

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

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 with all Celestron eyepieces.

Carrying Case (#302080) - This case fits both the NexStar 4 and NexStar 5 and is made of sturdy ABS plastic. It is

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

accessories..

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

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

• Super Modified Achromatic (SMA) Eyepieces: 11/4"

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

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

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

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) - Lanthanum is a unique rare earth glass used

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.

37

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

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.

Night Vision Flashlight - (#93588) - Celestron’s premium model for astronomy,

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) – An economical squeeze-type flashlight fitted with a

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 - These filters are designed to enhance

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

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

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

communication port capable of interfacing with popular astronomy software.

Moon Filter (#94119-A) - Celestron’s Moon Filter is an economical eyepiece filter for

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

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:

For 20

° to 40° of latitude #93720-30

For 30

° to 50°of latitude #93720-40

For 40

° to 60° of latitude #93720-50

Polarizing Filter Set (#93608) - The polarizing filter set limits the transmission of light to a specific plane, thus increasing

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

Sky Maps (#93722) - Celestron Sky Maps are the ideal teaching guide for learning the

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

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

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.

38

Tripod, NexStar - A stable tripod is a must for serious astronomical

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) - These pads rest between the ground

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).

39

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

102mm

Multi-layer coating process

Secondary Mirror Spot Size

Secondary Obstruction

1.25"

34.4% by diameter; 11% by area

Corrector Plate: Material

Coatings

BK-7 Optical Glass

A-R Coatings both sides

Highest Useful Magnification 240x ( ~ 6mm eyepiece)

Lowest Useful Magnification (7mm exit pupil) 15x ( ~ 80mm eyepiece)

Resolution: Rayleigh Criterion

Dawes Limit

1.36 arc seconds

1.14 arc seconds

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

1.0º

1.51º x 1.04º

Linear Field of View (at 1000 yds) 52.5 feet

Magnification: Standard Eyepiece

: Camera

55x

27x

Optical Tube Length 13.5 inches

Weight of Telescope 11 Lbs.

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Input Voltage

Maximum

Minimum

12 V DC Nominal

18 V DC Max.

8 V DC Min.

Batteries Required 8 AA Alkaline

Power Supply Requirements 12 VDC-750 mA (Tip positive)

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Motor: Type

Resolution

DC Servo motors with encoders, both axes

.26 arc sec

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

Hand Control

Double line, 16 character Liquid Crystal Display

19 fiber optic backlit LED buttons

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.

Enhanced information on over 100 objects

Total Object Database 4,033

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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 (310) 328-9560 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. (310) 328-9560

Fax. (310) 212-5835

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. (310) 328-9560

Fax. (310) 212-5835

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

11-00

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

quality control purposes and although they may appear on the hand control display they can not

be accessed by the user.

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

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

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

selected, the Model Select utility feature allows you to reset the hand control to its factory default

settings.

The Model Select feature has a Custom option that allows you to enter the exact encoder-gear

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 Model Select is displayed

on the screen, and press ENTER.

3. Use the Up and Down scroll keys to select Custom and press ENTER.

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.

Celestron International

Technical Support Department

2835 Columbia Street

Torrance, CA 90503

310-328-9560

310-212-5835 Fax

Monday – Friday 8am-4pm PST

ADDENDUM TO NEXSTAR 4

TELESCOPE MANUAL