Instruction manual | Celestron 4 Telescope User Manual

INSTRUCTION MANUAL
INTRODUCTION ........................................................................................................................................ 4
WARNING ................................................................................................................................................... 4
ASSEMBLY .................................................................................................................................................. 8
ASSEMBLING THE NEXSTAR ....................................................................................................................... 8
Powering the NexStar ............................................................................................................................ 8
The Hand Control .................................................................................................................................. 9
The Eyepiece.......................................................................................................................................... 9
The Star Pointer Finderscope.............................................................................................................. 10
HAND CONTROL ..................................................................................................................................... 12
HAND CONTROL OPERATION .................................................................................................................... 13
Alignment Procedure ........................................................................................................................... 13
Auto-Align............................................................................................................................................ 13
Two Star Alignment ............................................................................................................................. 15
Quick-Align.......................................................................................................................................... 15
NexStar Re-Alignment ......................................................................................................................... 16
OBJECT CATALOG ..................................................................................................................................... 16
Selecting an Object .............................................................................................................................. 16
Slewing to an Object............................................................................................................................ 16
Tour Mode ........................................................................................................................................... 17
DIRECTION BUTTONS ................................................................................................................................ 17
Rate Button .......................................................................................................................................... 17
SETUP PROCEDURES ................................................................................................................................. 18
Tracking Mode ................................................................................................................................................. 18
Tracking Rate ................................................................................................................................................... 18
View Time-Site ................................................................................................................................................ 18
Sidereal Time ................................................................................................................................................... 18
Filter Limits...................................................................................................................................................... 18
Date/Time ............................................................................................................................................ 19
User Defined Objects ....................................................................................................................................... 19
Get RA/DEC ........................................................................................................................................ 19
Get Alt-Az ............................................................................................................................................ 19
Goto R.A/Dec....................................................................................................................................... 19
Goto Alt-Az .......................................................................................................................................... 19
UTILITY FEATURES ................................................................................................................................... 20
Steup Time-Site................................................................................................................................................ 20
Anti-backlash ................................................................................................................................................... 20
Slew Limits ...................................................................................................................................................... 20
Direction Buttons ............................................................................................................................................. 20
Light Control .................................................................................................................................................... 20
Select Model..................................................................................................................................................... 20
RS-232.............................................................................................................................................................. 20
Hand Control Command Tree ............................................................................................................. 21
TELESCOPE BASICS............................................................................................................................... 22
IMAGE ORIENTATION ................................................................................................................................ 22
FOCUSING ................................................................................................................................................. 23
CALCULATING MAGNIFICATION ............................................................................................................... 23
DETERMINING FIELD OF VIEW .................................................................................................................. 23
GENERAL OBSERVING HINTS .................................................................................................................... 24
ASTRONOMY BASICS ................................................................................................................................ 25
THE CELESTIAL COORDINATE SYSTEM ..................................................................................................... 25
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MOTION OF THE STARS ............................................................................................................................. 26
POLAR ALIGNMENT (WITH OPTIONAL WEDGE) ......................................................................................... 27
Photography with the NexStar 4 .......................................................................................................... 28
Finding the North Celestial Pole ......................................................................................................... 28
CELESTIAL OBSERVING ...................................................................................................................... 30
OBSERVING THE MOON............................................................................................................................. 30
OBSERVING THE PLANETS......................................................................................................................... 30
OBSERVING THE SUN ................................................................................................................................ 31
OBSERVING DEEP SKY OBJECTS ............................................................................................................... 31
SEEING CONDITIONS ................................................................................................................................. 31
Transparency ....................................................................................................................................... 31
Sky Illumination ................................................................................................................................... 31
Seeing................................................................................................................................................... 32
TELESCOPE MAINTENANCE............................................................................................................... 33
CARE AND CLEANING OF THE OPTICS ....................................................................................................... 33
OPTIONAL ACCESSORIES .................................................................................................................. 34
APPENDIX A - TECHNICAL SPECIFICATIONS ............................................................................... 37
APPENDIX B - GLOSSARY OF TERMS............................................................................................... 38
APPENDIX C – MAPS OF TIME ZONES.............................................................................................. 41
SKY MAPS ................................................................................................................................................. 43
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Congratulations on your purchase of the Celestron NexStar! The NexStar ushers in a whole new generation of computer
automated technology. Simple and friendly to use, the NexStar is up and running after locating just two alignment stars.
It’s the perfect combination of power and portability. If you are new to astronomy, you may wish to start off by using the
NexStar's built-in Sky Tour feature, which commands the NexStar to find the most interesting objects in the sky and
automatically slews to each one. Or if you are an experienced amateur, you will appreciate the comprehensive database of
over 4,000 objects, including customized lists of all the best deep-sky objects, bright double stars and variable stars. No
matter at what level you are starting out, the NexStar will unfold for you and your friends all the wonders of the Universe.
Some of the many standard features of the NexStar include:
•
Incredible 4°/second slew speed.
•
Fully enclosed motors and optical encoders for position location.
•
Integrated hand controller – built into the side of the fork arm.
•
Storage for programmable user defined objects; and
Many other high performance features!
The NexStar’s deluxe features combined with Celestron’s legendary optical standards give amateur astronomers one of the
most sophisticated and easy to use telescopes available on the market today.
Take time to read through this manual before embarking on your journey through the Universe. It may take a few observing
sessions to become familiar with your NexStar, so you should keep this manual handy until you have fully mastered your
telescope’s operation. The NexStar hand control has built-in instructions to guide you through all the alignment procedures
needed to have the telescope up and running in minutes. Use this manual in conjunction with the on-screen instructions
provided by the hand control. The manual gives detailed information regarding each step as well as needed reference
material and helpful hints guaranteed to make your observing experience as simple and pleasurable as possible.
Your NexStar telescope is designed to give you years of fun and rewarding observations. However, there are a few things to
consider before using your telescope that will ensure your safety and protect your equipment.
Warning
Never look directly at the sun with the naked eye or with a telescope (unless you are using the proper solar
filter). Permanent and irreversible eye damage may result.
Never use your telescope to project an image of the sun onto any surface. Internal heat build-up can damage the
telescope and any accessories attached to it.
Never use an eyepiece solar filter or a Herschel wedge. Internal heat build-up inside the telescope can cause these
devices to crack or break, allowing unfiltered sunlight to pass through to the eye.
Never leave the telescope unsupervised, either when children are present or adults who may not be familiar with the
correct operating procedures of your telescope.
4
3
3
Eyepiece
StarPointer
1
Flip Mirror
Focuser Knob
Attach the included accessories (eyepiece and Star
Pointer finderscope) and remove the front lens
cover. Remove plastic cover over the battery and
turn-on the Star Pointer by rotating the dial on the
side. (For instructions on aligning the Star Pointer
see the Assembly section of the manual).
Remove the NexStar from its packaging and place
the base on a sturdy, level surface. Remove the
accessories from their individual boxes.
4
2
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.
The first time the NexStar is powered on the display will
read Select Model. Use the Up and Down scroll buttons to
select your NexStar model from the list and press ENTER.
When the display reads NexStar Ready, press ENTER to
AutoAlign the NexStar. The hand control display will ask
you to move the telescope tube so that it is level with the
ground and facing the north horizon. Use the direction
arrow buttons on the hand control to position the telescope
north and level. (See Astronomy Basics for help on finding
north).
5
5
7
Direction
Buttons
Catalog Keys
Up and Down
Scroll Buttons
Object List
Button
TOUR Button
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 alignment procedures).
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.
6
Star Pointer Finderscope
Alignment Star
The NexStar will automatically pick an alignment star and slew
the telescope close to that star. Once there, the display will ask
you to use the arrow buttons to aim the Star Pointer at the star. If
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
Alignment Successful".
Successful"
6
9
1
10
8
2
7
3
6
5
4
1
2
Optical Tube
Liquid Crystal Display
6
7
Focuser Knob
Straight Through Photographic Adapter
3
Hand Control
8
Flip Mirror Control
4
ON/OFF Switch
9
Eyepiece
5
Battery Compartment
10
Star Pointer Finderscope
7
The NexStar 4 comes completely pre-assembled and can be operational in a matter of minutes. The NexStar is conveniently
packaged in one reusable shipping carton that contains all of the following accessories:
•
•
•
25mm SMA Eyepiece – 1¼"
Star Pointer Finderscope
Computerized Hand Control with 4,000 Object Database
Assembling the NexStar
Start by removing the telescope from its shipping carton and setting the round base on a flat table or surface. It is best to
carry the telescope by holding it from the lower portion of the fork arm and from the bottom of the base. Remove all of the
accessories from their individual boxes. Remember to save all of the containers so that they can be used to transport the
telescope. Before the batteries can be installed, the telescope tube should be positioned horizontal to the ground. To do this,
gently rotate the front of the tube upwards until it is level with the ground.
Powering the NexStar
The NexStar can be powered by eight AA batteries (not included), an optional 12v AC adapter or an optional car battery
adapter. The battery compartment is located in the center of the telescope's base (see figure 3-1).
To power the NexStar with batteries:
1.
Remove the battery cover from the center of the base by
gently lifting up on the round portion of the cover.
2.
Insert the batteries into the battery compartment of the base.
3.
Reattach the battery compartment door by gently pushing
down on the cover until it snaps into place.
4.
Turn on the power to the NexStar by flipping the switch,
located at the base of the fork arm, to the "On" position.
Battery Compartment
Cover
Figure 3-1: The NexStar 4 Battery Compartment
8
The Hand Control
The hand control is located on the side of the fork arm and can be removed and used remotely or used while attached to the
fork. The hand control attaches to the fork arm by resting on two posts, located on the bottom of the hand control cradle,
and a clip inside the fork arm. To remove the hand control from the fork arm cradle, gently lift the hand control upwards
and pull out. To return the hand control into the fork arm, lower the hand control into the cradle so that the two holes in the
bottom of the hand control go over the posts on the bottom of the cradle, and the opening in the back of the hand control
slides over the clip inside the fork arm.
Once the telescope is powered up, the hand control can be used to move the optical tube in altitude (up and down) and
azimuth (side to side). Use the Up arrow directional button to move the telescope tube until it is roughly parallel to the
ground. This will make it more convenient to attach the necessary accessories as well as remove the front lens cover and
install batteries when they are needed.
You are now ready to attach the included visual accessories onto the telescope optical tube.
The Eyepiece
The eyepiece, or ocular, is the optical element that magnifies the
image focused by the telescope. The NexStar 4 has an internal
diagonal mirror that diverts light to the eyepiece barrel on top of
the telescope's rear cell. The eyepiece fits into the barrel built-in
to the rear cell. To install the eyepiece:
1.
Loosen the thumbscrew on the eyepiece barrel so it does not
obstruct the inner diameter of the barrel.
2.
Slide the chrome portion of the eyepiece into the eyepiece barrel.
3.
Tighten the thumbscrew to hold the eyepiece in place.
Eyepiece
StarPointer
Diagonal
Barrel
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.”
Flip Mirror Control
Focuser Knob
Figure 3-2 – The Rear Cell with Visual Accessories
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.
Note:
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).
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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:
ON/OFF
Variable Brightness
Control
Glass Window
Azimuth Control
Knob
Mounting Track
Altitude Control
Knob
Dovetail Mounting Bracket
Figure 3-3: The Star Pointer Finderscope with Mounting Bracket
Star Pointer Installation
1.
Locate the dovetail mounting bracket on the rear cell of the optical tube.
2.
Slide the mounting track at the bottom of the Star Pointer over the dovetail portion of the bracket. It may be necessary
to loosen the two screws on the side of the mounting track before sliding it over the dovetail. The end of the Star
Pointer with the glass window should be facing out towards the front of the telescope.
3. Tighten the two screws on the side of the mounting track to secure the Star Pointer to the dovetail bracket.
Star Pointer Operation
The star pointer is powered by a long life 3-volt lithium battery (#CR2032) located underneath the front portion of the Star
Pointer. Like all finderscopes, the Star Pointer must be properly aligned with the main telescope before it can be used. This
is a simple process using the azimuth and altitude control knobs located on the side and bottom of the Star Pointer. The
alignment procedure is best done at night since the LED dot will be difficult to see during the day.
1.
To turn on the Star Pointer, rotate the variable brightness control (see figure 3-3) clockwise until you here a
"click". To increase the brightness level of the red dot, continue rotating the control knob about 180º until it stops.
Remember to remove the plastic cover over the battery, and always turn the power off after you have found
an object. This will extend the life of both the battery and the LED.
2.
Locate a bright star or planet and center it in a low power eyepiece in the main telescope.
3.
With both eyes open, look through the glass window at the alignment star.
4.
If the Star Pointer is perfectly aligned, you will see the red LED dot overlap the alignment star. If the Star Pointer
is not aligned, take notice of where the red dot is relative to the bright star.
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5.
Without moving the main telescope, turn the Star Pointer's azimuth and altitude alignment controls until the red
dot is directly over the alignment star.
If the LED dot is brighter than the alignment star, it may make it difficult to see the star. Turn the variable brightness
control counterclockwise, until the red dot is the same brightness as the alignment star. This will make it easier to get an
accurate alignment. The Star Pointer is now ready to be used.
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The NexStar 4 has a removable hand controller built into the side of the fork arm designed to give you instant access to all
the functions the NexStar has to offer. With automatic slewing to over 4,000 objects, and common sense menu
descriptions, even a beginner can master its variety of features in just a few observing sessions. Below is a brief description
of the individual components of the NexStar 4 hand controller:
1.
2.
3.
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.
Align: Instructs the NexStar to use a selected star or object as an alignment position.
Direction Keys: Allows complete control of the NexStar in any direction. Use the direction keys to center objects in
the StarPointer finderscope and eyepiece.
1
7
2
8
3
9
10
4
5
11
6
12
Figure 4-1
The NexStar Hand Control
4.
Catalog Keys: The NexStar has a key on the hand control to allow direct access to each of the catalogs in its 4,000+
object database. The NexStar contains the following catalogs in its database:
Messier – Complete list of all Messier objects.
NGC – Select list of all the deep-sky objects in the Revised New General Catalog.
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Caldwell – A combination of the best NGC and IC objects.
Planets - All 8 planets in our Solar System plus the Moon.
Stars – A compiled list of the brightest stars from the SAO catalog.
List – For quick access, all of the best and most popular objects in the NexStar database have been broken
down into lists based on their type and/or common name:
Named Stars
Named Objects
Double Stars
Variable Stars
Asterisms
Common name listing of the brightest stars in the sky.
Alphabetical listing of over 50 of the most popular deep
sky objects.
Numeric-alphabetical listing of the most visually stunning
double, triple and quadruple stars in the sky.
Select list of the brightest variable stars with the shortest
period of changing magnitude.
A unique list of some of the most recognizable star
patterns in the sky.
5.
6.
Info: Displays coordinates and useful information about objects selected from the NexStar database.
Tour: Activates the tour mode, which seeks out all the best objects for a given month and automatically slews the
NexStar to those objects.
7. Enter: Pressing Enter allows you to select any of the NexStar functions, accept entered parameters and slew the
telescope to displayed objects.
8. Undo: Undo will take you out of the current menu and display the previous level of the menu path. Press Undo
repeatedly to get back to a main menu or use it to erase data entered by mistake.
9. Menu: Displays the many setup and utilities functions such as tracking rate and user defined objects and many
others.
10. Scroll Keys: Used to scroll up and down within any of the menu lists. A double arrow symbol on the right side of
the LCD indicates that the scroll keys can be used to view additional information.
11. Rate: Instantly changes the rate of speed of the motors when the direction buttons are pressed.
12. RS-232 Jack: Allows you to interface with a computer and control the NexStar remotely.
Hand Control Operation
This section describes the basic hand control procedures needed to operate the NexStar. These procedures are grouped into
three categories: Alignment, Setup and Utilities. The alignment section deals with the initial telescope alignment as well as
finding objects in the sky; the setup section discusses changing parameters such as tracking mode and tracking rate; finally,
the last section reviews all of the utility functions such as adjusting the telescopes slew limits and backlash compensation.
Alignment Procedure
In order for the NexStar to accurately point to objects in the sky, it must first be aligned with two known positions (stars) in
the sky. With this information, the telescope can create a model of the sky, which it uses to locate any object with known
coordinates.
Auto-Align
Auto-Align is the easiest way to get your NexStar aligned and ready to observe. Even if you do not know a single star in the
sky, the NexStar will align itself by guiding the user through the alignment procedure by asking for basic information like
the date, time and location. The NexStar will then automatically choose two stars for alignment and roughly center the stars
in the field of view of the Star Pointer. Before the telescope is ready to be aligned, it should be set up in an outside location
with all accessories (eyepiece and Star Pointer) attached and lens cover removed as described in the Assembly section of the
manual.
1.
Once the NexStar is powered on the display will read NexStar Ready. Press ENTER to begin alignment.
The first time that the NexStar is used, it will request information to help identify the model of telescope. Once powered on,
the hand control will display the message Select Model.
Model Use the Up and Down menu keys (10) to scroll through the
different NexStar models. Press ENTER when your NexStar model is displayed on the hand control. This information will
be retained for future use and will not be displayed again. If for some reason the incorrect model was selected or you wish
13
to use your hand control on a different NexStar model, the Select Model utility feature allows you to re-select the proper
NexStar model from the displayed list (see Select Model later in this section).
2.
3.
4.
Use the Up and Down scroll keys to select AutoAlign if it is not already displayed, and press ENTER.
The telescope will then ask you to use the direction keys (3) to level the telescope tube and point the front of the
telescope towards north. North can be found by finding the direction of the North Star (Polaris) or by using a compass.
You do not need to point at the North Star, only the north horizon. Alignment only needs to be approximate, however a
close alignment will make the auto alignment more accurate. Once the telescope is in the north and level position, press
ENTER.
The hand control display will then ask for the following information:
Location - The NexStar will display a list of cities to choose from. Choose the city from the database that is closest to
your current observing site. The city you choose will be remembered in the hand controls memory so that
it will be automatically displayed the next time an alignment is done. Alternatively, if you know the exact
longitude and latitude of your observing site, it can be entered directly into the hand control and
remembered for future use as well. To choose a location city:
Use the Up and Down scroll keys to choose between City Database and Custom Site. City Database will allow
you to select the closest city to your observing site from a list of either international or U.S. location. Custom Site
allows you to enter the exact longitude and latitude of your observing site. Select City Database and press
ENTER.
The hand control will allow you to choose from either U.S. or international locations. For a listing of U.S.
locations by state and then by city, press ENTER while United States is displayed. For international locations,
use the Up or Down scroll key to select International and press ENTER.
To display a list of local cities, first select your state from the alphabetical listing (or a list of countries if
International locations was selected) and press ENTER.
Choose the closest city to your location from the displayed list and press ENTER.
Time -
Enter the current time for your area. You can enter either the local time (i.e. 8:00), or you can enter military
time (i.e. 20:00).
Select PM or AM. If military time was entered, the hand control will bypass this step.
Choose between Standard time or Daylight Savings time. Use the Up and Down scroll buttons (10) to toggle
between options.
Helpful
Hints
Select the time zone that you are observing from. Again, use the Up and Down buttons (10) to scroll through the
choices. For time zone information, refer to the Time Zone map in the appendix of this manual.
Date -
Enter the month, day and year of your observing session. The display will read: mm/dd/yy.
•
If the wrong information has been input into the hand control, the UNDO button will act as a backspace allowing
the user to re-enter information.
•
The next time that your NexStar is Auto Aligned, the hand control will automatically display the last location
(either a city or longitude/latitude) that was entered. Pressing the UNDO button will allow you to go back and
select a new city location or longitude/latitude.
Based on this information, the NexStar will automatically select a bright star that is above the horizon and slew towards it. At
this point the telescope is only roughly aligned, so the alignment star should only be close to the field of view of the Star
Pointer finder. Once finished slewing, the display will ask you to use the arrow buttons to align the selected star with the red
dot in the center of the Star Pointer. If for some reason the chosen star is not visible (perhaps behind a tree or building) you
can press UNDO to select and slew to a different star. Once centered in the finder, press ENTER. The display will then
instruct you to center the star in the field of view of the eyepiece. When the star is centered, press ALIGN to accept this star
as your first alignment star. (There is no need to adjust the slewing rate of the motors after each alignment step. The NexStar
automatically selects the best slewing rate for aligning objects in both the Star Pointer and the eyepiece). After the first
alignment star has been entered the NexStar will automatically slew to a second alignment star and have you repeat the same
14
procedure for that star. When the telescope has been aligned to both stars the display will read Alignment Successful,
Successful
and you are now ready to find your first object.
Observing
Tips
If the wrong star was centered and aligned to, the NexStar display will read Align Failed.
Failed Press UNDO to begin the
alignment procedure again.
If you are not sure if the correct star was centered, always remember that the alignment star will be the brightest
star nearest the field of view of the finder. There may be other fainter stars visible that are closer to the center of the
Star Pointer, but the actual alignment star will be obviously brighter than any other star in the area.
For the best possible pointing accuracy, always center the alignment stars using the up arrow button and the right
arrow button. Approaching the star from this direction when looking through the eyepiece will eliminate much of the
backlash between the gears and assure the most accurate alignment possible.
Two Star Alignment
With the two-star alignment method, the NexStar requires the user to know the positions of only two bright stars in order to
accurately align the telescope with the sky and begin finding objects. Here is an overview of the two-star alignment
procedure:
1.
2.
3.
4.
5.
6.
Once the NexStar is powered on, use the Up and Down scroll keys to select TwoTwo-Star Align,
Align and press
ENTER.
The NexStar display will ask you to move the telescope tube until it is horizontal to the ground. To do this, use
the direction keys (3) to move the telescope until it is roughly level with the ground. Press ENTER.
The SELECT STAR 1 message will appear in the top row of the display. Use the Up and Down scroll keys (10) to
select the star you wish to use for the first alignment star. Press ENTER.
NexStar then asks you to center in the eyepiece the alignment star you selected. Use the direction buttons to slew
the telescope to the alignment star and carefully center the star in the eyepiece.
Once the alignment star is centered in the field of view of the eyepiece, press the ALIGN key (2) to accept this
position.
NexStar will then ask you to select and center a second alignment star and press the ALIGN key. It is best to
choose alignment stars that are a good distance away from one another. Stars that are at least 40º to 60º apart from
each other will give you a more accurate alignment than stars that are close to each other.
Once the second star alignment is completed properly, the display will read Alignment Successful,
Successful and you will hear the
tracking motors turn-on and begin to track.
Quick-Align
Quick-Align allows you to input all the same information as you would for the AutoAlign procedure. However, instead of
slewing to two alignment stars for centering and alignment, the NexStar bypasses this step and simply models the sky based
on the information given. This will allow you to roughly slew to the coordinates of bright objects like the moon and planets
and gives the NexStar the information needed to track objects in altazimuth in any part of the sky. Quick-Align is not meant
to be used to accurately locate small or faint deep-sky objects or to track objects accurately for photography. Note: Once a
Quick-Align has been done, you can use the Re-alignment feature (see below) to improve your telescopes pointing and
tracking accuracy.
To use Quick-Align:
1.
2.
3.
Select Quick-Align from the alignment options.
Use the arrow buttons to level the tube and position the telescope tube towards north and press ENTER.
The hand control will then ask you to input all the same time and location information as you would for the
AutoAlign procedure.
Once entered, the NexStar will model the sky based on this information and display Alignment Successful.
Successful
15
NexStar Re-Alignment
The NexStar has a re-alignment feature which allows you to replace either of the two original alignment stars with a new
star or celestial object. This can be useful in several situations:
•
•
If you are observing over a period of a few hours, you may notice that your original two alignment stars have
drifted towards the west considerably. (Remember that the stars are moving at a rate of 15º every hour).
Aligning on a new star that is in the eastern part of the sky will improve your pointing accuracy, especially on
objects in that part of the sky.
If you have aligned your telescope using the Quick-Align method, you can use re-align to align to two actual
objects in the sky. This will improve the pointing accuracy of your telescope without having to re-enter
addition information.
To replace an existing alignment star with a new alignment star:
1.
2.
3.
4.
5.
6.
7.
Select the desired star (or object) from the database and slew to it.
Carefully center the object in the eyepiece.
Once centered, press the UNDO button until you are at the main menu.
With NexStar Ready displayed, press the ALIGN key on the hand control.
The display will then ask you which alignment star you want to replace.
Use the UP and Down scroll keys to select the alignment star to be replaced, and press ENTER. It is usually
best to replace the star closest to the new object. This will space out your alignment stars across the sky.
Press ALIGN to make the change.
Object Catalog
Selecting an Object
Now that the telescope is properly aligned, you can choose an object from any of the catalogs in the NexStar's extensive
database. The hand control has a key designated for each of the catalogs in its database. There are two ways to select objects
from the database: scrolling through the named object lists and entering object numbers.
•
Pressing the LIST key on the hand control will access all objects in the database that have common names or
types. Each list is broken down into the following categories: Named Stars, Named Object, Double Stars,
Variable Stars and Asterisms. Selecting any one of these options will display an alpha-numeric listing of the
objects under that list. Pressing the Up and Down keys allows you to scroll through the catalog to the desired
object.
•
Pressing any of the catalog keys (M, CALD, NGC, or STAR) will display a blinking cursor below the name
of the catalog chosen. Use the numeric key pad to enter the number of any object within these standardized
catalogs. For example, to find the Orion Nebula, press the "M" key and enter "042".
•
Pressing the PLANET button will allow you to use the UP and DOWN arrow keys to scroll through and
select the eight planets as well as the moon.
More
Information
To download a list of all the stars contained in the STAR Catalog with SAO number cross references, logon to our web site
at www.celestron.com.
Slewing to an Object
Once the desired object is displayed on the hand control screen, you have two options:
1.
Press the INFO Key. This will give you useful information about the selected object such as magnitude,
constellation and fascinating facts about many of the objects.
16
The speed at which information scrolls across the hand control display can be changed while the information is being
viewed:
•
Press the “1” key repeatedly to speed up the scroll speed.
•
Press the “4” key repeatedly to slow down the scroll speed.
•
Press the “7” key to freeze and unfreeze the information on the display.
2.
Press the ENTER Key. This will automatically slew the telescope to the coordinates of the object. While the
telescope is slewing to the object, the user can still access many of the hand control functions (such as displaying
information about the object).
If you slew to an object that is below the horizon, NexStar will notify you by displaying a message reminding you that you
have selected an object outside of your slew limits (see Slew Limits in the Utility Features section of the manual). Press
UNDO to go back and select a new object. Press ENTER to ignore the message and continue the slew. The NexStar hand
control will only display objects that are below the horizon if the Filter Limits are set below 0º in altitude. See Filter Limits
in the Utility Feature section of the manual for more information on setting the filter limits.
Caution: Never slew the telescope when someone is looking into the eyepiece. The telescope can move at fast slew
speeds and may hit an observer in the eye.
Object information can be obtained without having to do a star alignment. After the telescope is powered on, pressing any
of the catalog keys allows you to scroll through object lists or enter catalog numbers and view the information about the
object as described above.
Tour Mode
The NexStar includes a tour feature which automatically allows the user to choose from a list of interesting objects based on
the date and time in which you are observing. The automatic tour will display only those objects that are within your set
filter limits. To activate the Tour mode, press the TOUR key (6) on the hand control. The NexStar will display the best
objects to observe that are currently in the sky.
•
•
•
To see information and data about the displayed object, press the INFO key.
To slew to the object displayed, press ENTER.
To see the next tour object, press the Down key.
Direction Buttons
The NexStar has four direction buttons in the center of the hand control which control the telescope motion in altitude (up
and down) and azimuth (left and right). The telescope can be controlled at nine different speed rates.
1
2
3
4
5
=
=
=
=
=
2x
4x
8x
16x
32x
6
7
8
9
=
=
=
=
.5º / sec
1º / sec
2º / sec
4º / sec
Nine available slew speeds
Rate Button
Pressing the RATE key (11) allows you to instantly change the speed rate of the motors from high speed slew rate to precise
guiding rate or anywhere in between. Each rate corresponds to a number on the hand controller key pad. The number 9 is
the fastest rate (4º per second, depending on power source) and is used for slewing between objects and locating alignment
stars. The number 1 on the hand control is the slowest rate (2x sidereal) and can be used for accurate centering of objects in
the eyepiece. To change the speed rate of the motors:
17
•
•
Press the RATE key on the hand control. The LCD will display the current speed rate.
Press the number on the hand control that corresponds to the desired speed.
The hand control has a "double button" feature that allows you to instantly speed up the motors without having to choose a
speed rate. To use this feature, simply press the arrow button that corresponds to the direction that you want to move the
telescope. While holding that button down, press the opposite directional button. This will increase the speed to the
maximum slew rate.
Setup Procedures
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.
When using the telescope for terrestrial (land) observation, the tracking
can be turned off so that the telescope never moves.
Off
Tracking Rate - In addition to being able to move the telescope with the hand control buttons, the NexStar will
continually track a celestial object as it moves across the night sky. The tracking rate can be changed
depending on what type of object is being observed:
Sidereal
Lunar
Solar
This rate compensates for the rotation of the earth by moving the
telescope at the same rate as the rotation of the earth, but in the opposite
direction. When the telescope is polar aligned, this can be accomplished
by moving the telescope in Right Ascension only. When mounted in AltAz mode, the telescope must make corrections in both R.A. and
declination.
Used for tracking the moon when observing the lunar landscape.
Used for tracking the Sun when solar observing using a proper solar filter.
View Time-Site - View Time-Site will display the last saved time and longitude/latitude entered in the hand control.
Sidereal Time – Displays the Sidereal time for your current time and location. This is useful for knowing the right
ascension of celestial objects that are located on the local meridian at that time.
Filter Limits – When an alignment is complete, the NexStar automatically knows which celestial objects are above the
horizon. As a result, when scrolling through the database lists (or selecting the Tour function), the NexStar hand control
will display only those objects that are known to be above the horizon when you are observing. You can customize the
object database by selecting altitude limits that are appropriate for your location and situation. For example, if you are
observing from a mountainous location where the horizon is partially obscured, you can set your minimum altitude limit to
read +20º. This will make sure that the hand control only displays objects that are higher in altitude than 20º.
18
Observing
Tip!
If you want to explore the entire object database, set the maximum altitude limit to 90º and the minimum limit to –90º. This
will display every object in the database lists regardless of whether it is visible in the sky from your location.
User Defined Objects - The NexStar can store up to 50 different user defined objects in its memory. The objects can
be daytime land objects or an interesting celestial object that you discover that is not included
in the regular database. There are several ways to save an object to memory depending on
what type of object it is:
Save Sky Object:
The NexStar stores celestial objects to its database by saving its right ascension and
declination in the sky. This way the same object can be found each time the telescope is
aligned. Once a desired object is centered in the eyepiece, simply scroll to the "Save
Save Sky
Obj" command and press ENTER. The display will ask you to enter a number between 1-25
to identify the object. Press ENTER again to save this object to the database.
Save Land Object:
The NexStar can also be used as a spotting scope on terrestrial objects. Fixed land objects
can be stored by saving their altitude and azimuth relative to the location of the telescope at
the time of observing. Since these objects are relative to the location of the telescope, they
are only valid for that exact location. To save land objects, once again center the desired
object in the eyepiece. Scroll down to the "Save
Save Land Obj"
Obj command and press
ENTER. The display will ask you to enter a number between 1-25 to identify the object.
Press ENTER again to save this object to the database.
Enter R.A. - Dec:
You can also store a specific set of coordinates for an object just by entering the R.A. and
declination for that object. Scroll to the "Enter
Enter RARA-DEC " command and press ENTER.
The display will then ask you to enter first the R.A. and then the declination of the desired
object.
GoTo Object:
To go to any of the user defined objects stored in the database, scroll down to either GoTo
Sky Obj or Goto Land Obj and enter the number of the object you wish to select and
press ENTER. NexStar will automatically retrieve and display the coordinates before
slewing to the object.
To replace the contents of any of the user defined objects, simply save a new object using one of the existing identification
numbers; NexStar will replace the previous user defined object with the current one.
Get RA/DEC - Displays the right ascension and declination for the current position of the telescope.
Get Alt-Az - Displays the relative altitude and azimuth for the current position of the telescope.
Goto R.A/ Dec - Allows you to input a specific R.A. and declination and slew to it.
Goto Alt-Az
Helpful
Hint
- 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.
19
Utility Features
Scrolling through the MENU options will also provide access to several advanced utility functions such as anti-backlash
compensation and slew limits.
Setup Time-Site - Allows the user to customize the NexStar display by changing time and location parameters (such as
time zone and daylight savings).
Anti-backlash – All mechanical gears have a certain amount of backlash or play between the gears. This play is evident
by how long it takes for a star to move in the eyepiece when the hand control arrow buttons are pressed (especially when
changing directions). The NexStar's anti-backlash features allows the user to compensate
for backlash by inputting a value which quickly rewinds the motors just enough to
eliminate the play between gears. The amount of compensation needed depends on the
slewing rate selected; the slower the slewing rate the longer it will take for the star to
U T ILIT IE S
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
S E T U P T IM E -S IT E
photographic guiding.
AN T I-BAC K L AS H
M
ENU
To set the anti-backlash value, scroll down to the anti-backlash option and press ENTER.
Enter a value from 0-100 for both azimuth and altitude directions and press ENTER after
each one to save these values. NexStar will remember these values and use them each time
it is turned on until they are changed.
Slew Limits – Sets the limits in altitude that the telescope can slew without displaying a
warning message. The slew limits prevent the telescope tube from slewing to an object
below the horizon or slewing to an object that is high enough that the tube might hit one of
the tripod legs. However, the slew limits can be customized depending on your needs.
For example, if you would like to slew to an object that is close to the zenith and are certain
that the tube will not hit the tripod legs, you can set the slew limits to 90º in altitude. This
will allow the telescope to slew to any object above the horizon without warning.
Direction Buttons –The direction a star moves in the eyepiece varies depending on the
accessories being used. This can create confusion when guiding on a star using an off-axis
guider versus a straight through guide scope. To compensate for this, the direction of the
drive control keys can be changed. To reverse the button logic of the hand control, press
the MENU button and select Direction Buttons from the Utilities menu. Use the Up/Down
arrow keys (10) to select either the Azimuth buttons (left and right) or Altitude buttons (up
and down) and press ENTER. Pressing ENTER again will reverse the direction of the hand
control buttons from their current state. Direction Buttons will only change the eyepiece
rates (rate 1-6) and will not affect the slew rates (rate 7-9).
A Z M P O S IT IV E
A Z M N E G A T IV E
A L T P O S IT IV E
A L T N E G A T IV E
S L E W LIM IT S
SLEW ALT M AX
S L E W A L T M IN
D IR E C T IO N BU T T O N S
AZM B UTTO NS
ALT B UTTO NS
L IG H T C O N T R OL
D IS P L A Y O F F
D IS P L A Y O N
KEY PAD O FF
KEY PAD ON
SELECT M ODEL
Light Control – This feature allows you to turn off both the red key pad light and LCD display for daytime use to
conserve power and to help preserve your night vision.
Select Model – The first time the NexStar is powered on, the hand control display allows you to select your NexStar
from a list of different models. If for some reason the incorrect model was selected or you wish to use your hand control on
a different NexStar model, the Select Model utility feature allows you to re-select the proper NexStar model from the
displayed list. Once the correct NexStar model has been selected the power needs to be restarted before beginning the
alignment procedure. The Select Model feature will return the hand control to its original factory settings. Parameters such
as backlash compensation values along with slew and filter limits will be reset. However, stored parameters such as user
defined objects will remain saved even after the model has been changed.
RS-232 - The NexStar has a RS-232 port located on the bottom of the hand control that allows it to communicate with
many astronomy computer programs such as The Sky by Software Bisque. Before attempting to create a link with a
computer, select the RS-232 option and press Enter.
20
NexStarReady
M ENU
T R ACK IN G
M ODE
A L T -A Z
EQ NO RTH
E Q S O UTH
OFF
R AT E
S ID E R E A L
SOLAR
LUNAR
V IE W T IM E -S IT E
S IDE R E AL T IM E
FILT E R LIM IT S
A L T M A X IN L IS T
A L T M IN IN L IS T
U T ILIT IE S
S E TU P TIM E /S ITE
A N TI-B A C K L A S H
S L E W L IM ITS
D IR E C TIO N B U TTO N S
L IG H T C O N TR O L
SELECT MODEL
R S -2 3 2
U S E R OBJE C T S
G O TO S K Y O B J
SAVE SKY OBJ
E NTE R RA & DE C
G O TO LA ND O B J
SAVE LAND OBJ
G E T ALT -AZ
G OT O ALT -AZ
G E T R A-D E C
G OT O R A-D E C
A L IG NM ENT
L IST
AU T O ALIG N
P O IN T T U B E N O R T H & L E V E L
CIT Y DAT ABASE
Un ited States
Ch oose State
NA M E D S TA R
N A M E D O B JE C T
A S T E R IS M S
TOUR
V A R IA B L E S T A R
DO UBLE S TA R
CALDW ELL
M E S S IE R
NGC
S O LA R S Y S TE M
SAO
Ch oose City
E n ter Tim e
E n ter Date
In te rn a tio n a l
Ch oose Cou n try
Ch oose City
CUS T O M S IT E
En ter Lon g /Lat
E n ter Tim e
E n ter Date
T W O-S T AR ALIG NM E NT
LEVEL TUBE
SELECT STAR 1
CENTER STAR 1
SELECT STAR 2
CENTER STAR 2
QU IC K ALIG N
P O IN T T U B E N O R T H & L E V E L
SELECT LO CAT IO N
ENTER T IM E
E N T ER DA T E
NexStar Menu Tree:
The following figure is a menu tree showing the sub-menus associated with the primary command
functions
21
A telescope is an instrument that collects and focuses light. The nature of the optical design determines how the light is focused.
Some telescopes, known as refractors, use lenses. Other telescopes, known as reflectors, use mirrors. The Maksutov-Cassegrain
optical system uses a combination of mirrors and lenses and is referred to as a compound or catadioptric telescope. This unique
design offers large-diameter optics while maintaining very short tube lengths, making them extremely portable. The MaksutovCassegrain system consists of a corrector plate, a spherical primary mirror, and a secondary mirror spot. Once light rays enter the
optical system, they travel the length of the optical tube three times.
Figure 5-1
A cutaway view of the light path of the Maksutov-Cassegrain optical design
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.
Image Orientation
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.
Fig 5-2a - Actual image
orientation as seen with the
unaided eye
Fig 5-2b - Reversed from left to
right, as viewed through the
eyepiece
22
Focusing
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.
Figure 5-3
The emblem on the end of
the focus knob shows the
correct rotational direction
for focusing the NexStar.
Calculating Magnification
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.
Determining Field of View
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).
23
General Observing Hints
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.
24
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.
The Celestial Coordinate System
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 6-1
The celestial sphere seen from the outside showing R.A. and DEC.
25
Motion of the Stars
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 6-2
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).
26
Polar Alignment (with optional Wedge)
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.
Warning!
Polar alignment is the process by which the telescope's axis of rotation (called the polar axis) is aligned (made parallel)
with the Earth's axis of rotation. Once aligned, a telescope with a clock drive will track the stars as they move across
the sky. The result is that objects observed through the telescope appear stationary (i.e., they will not drift out of the
field of view). If not using the clock drive, all objects in the sky (day or night) will slowly drift out of the field. This
motion is caused by the Earth's rotation.
Remember, whenever attaching the NexStar to the NexStar tripod or wedge, always use the bolts that come with the
accessory. Never use bolts that thread more than 3/8" into the bottom of the NexStar base. Threading bolts more than
3/8" into the base will damage the internal gears.
Whether you are using your NexStar in the Alt-Az configuration or polar aligned, it will be necessary to locate where
north is and more specifically where the North Star is.
Definition
The polar axis is the axis around which the telescope rotates when moved in right ascension. This axis points
the same direction even when the telescope moves in right ascension and declination.
Aligning the NexStar 4 on a Wedge
In order to do a star alignment while using the NexStar on an
equatorial wedge it will be necessary to use the Two-Star
alignment method rather than the AutoAlign method. 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 Two-Star alignment
procedure as described in the Hand Control section of the
manual. When doing a Two-Star alignment while using an
equatorial wedge, remember the following:
When the hand control instructs you to point the telescope
tube north and level, make sure that the tube is positioned
perpendicular (at a 90º angle) to the fork arm with the tube
facing down. This is the same position that you would have
the tube if you were aligning the telescope in Altazimuth.
After the alignment is complete, remember that your slew and
filter limits are defined relative to the base of the telescope.
This means that an altitude slew limit of 80º instructs the
NexStar to avoid slewing to any objects that is closer than 10º
from being parallel with the fork arm.
Figure 6-3
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.
Filter limits should be set so that the entire database will be displayed. Set the maximum altitude limit to read 90º and
the minimum altitude limit to –90º. This will allow you to view and choose any object in the database.
27
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.
Attaching a Camera to the NexStar
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 Tadapter (#93635-A) and a T-ring specific to the brand of
camera being used. To attach the photographic accessories:
1.
2.
3.
4.
5.
Remove the screw-on cover from the photo
adaptor port on the rear cell.
Thread the T-adapter securely onto the photo
adapter port.
Thread the T-ring onto the exposed end of the Tadapter.
Remove any lens from the body of your camera.
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.
Camera Body
T-Ring
T-Adapter
Figure 6-4 – NexStar with photographic Accessories
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.
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.
Figure 6-5
The position of the Big
Dipper changes throughout
the year and the night.
28
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 6-5). The
position of the Big Dipper changes during the year and throughout the course of the night (see Figure 6-5). 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 6-6). 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.
Definition
The north celestial pole is the point in the northern hemisphere around which all stars
appear to rotate. The counterpart in the southern hemisphere is referred to as the south
celestial pole.
Figure 6-6
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.
29
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.
Observing the Moon
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.
Lunar Observing Hints
•
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.
Observing the Planets
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.
Planetary Observing Hints
•
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.
30
Observing the Sun
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.
Solar Observing Hints
•
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.
Observing Deep Sky Objects
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.
Seeing Conditions
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.
31
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 7-1
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.
32
While your NexStar telescope requires little maintenance, there are a few things to remember that will ensure your telescope
performs at its best.
Care and Cleaning of the Optics
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 service department. If your telescope is in need of
internal cleaning, please call the factory for a return authorization number and price quote.
33
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.
CD-ROM (#93700) - Celestron and Software Bisque have joined together to present
this comprehensive CD-ROM called The Sky™ Level 1 - from Celestron. It features a
10,000 object database, 75 color images, horizontal projection, custom sky chart
printing, zoom capability and more! A fun, useful and educational product. PC
format.
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
34
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.
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).
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
For 30° to 50°of latitude
For 40° to 60° of latitude
#93720-30
#93720-40
#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.
35
Tripod, NexStar (#93497) - 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).
36
Appendix A - Technical Specifications
O
Oppttiiccaall S
Sppeecciiffiiccaattiioonn
Design
Aperture
Focal Length
F/ratio of the Optical System
Primary Mirror:
Diameter
Coatings
Secondary Mirror Spot Size
Secondary Obstruction
Corrector Plate:
Material
Coatings
Highest Useful Magnification
Lowest Useful Magnification (7mm exit pupil)
Resolution: Rayleigh Criterion
Dawes Limit
Photographic Resolution
Light Gathering Power
Near Focus standard eyepiece or camera
Field of View: Standard Eyepiece
: 35mm Camera
Linear Field of View (at 1000 yds)
Magnification: Standard Eyepiece
: Camera
Optical Tube Length
Weight of Telescope
Maksutov-Cassegrain Catadioptric
4 inches (102mm)
52 inches (1325mm)
13
102mm
Multi-layer coating process
1.25"
34.4% by diameter; 11% by area
BK-7 Optical Glass
A-R Coatings both sides
240x ( ~ 6mm eyepiece)
15x ( ~ 80mm eyepiece)
1.36 arc seconds
1.14 arc seconds
140 lines/mm
212x unaided eye
~ 20 feet
1.0º
1.51º x 1.04º
52.5 feet
53x
27x
13.5 inches
11 Lbs.
E
Elleeccttrroonniicc S
Sppeecciiffiiccaattiioonnss
Input Voltage
Maximum
Minimum
Batteries Required
Power Supply Requirements
12 V DC Nominal
18 V DC Max.
8 V DC Min.
8 AA Alkaline
12 VDC-750 mA (Tip positive)
M
Meecchhaanniiccaall S
Sppeecciiffiiccaattiioonnss
Motor: Type
Resolution
Slew speeds
Hand Control
Fork Arm
DC Servo motors with encoders, both axes
.26 arc sec
Nine slew speeds: 4º /sec, 2º /sec, 1º/sec, .5/sec, 32x, 16x, 8x, 4x, 2x
Double line, 16 character Liquid Crystal Display
19 fiber optic backlit LED buttons
Cast aluminum, with integrated hand control receptacle
S
Sooffttw
waarree S
Sppeecciiffiiccaattiioonnss
Software Precision
Ports
Tracking Rates
Tracking Modes
Alignment Procedures
Database
16 bit, 20 arc sec. calculations
RS-232 communication port on hand control
Sidereal, Solar, Lunar and King
Alt-Az, EQ North & EQ South
AutoAlign (2-star alignment)
25 user defined programmable object.
Enhanced information on over 100 objects
Total Object Database
4,033
37
Appendix B - Glossary of Terms
AAbsolute magnitude
Airy disk
Alt-Azimuth Mounting
Altitude
Aperture
Apparent Magnitude
Arcminute
Arcsecond
Asterism
Asteroid
Astrology
Astronomical unit (AU)
Aurora
Azimuth
BBinary Stars
CCelestial Equator
Celestial pole
Celestial Sphere
Collimation
DDeclination (DEC)
EEcliptic
Equatorial mount
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.
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.
A telescope mounting using two independent rotation axis allowing movement of the instrument in
Altitude and Azimuth.
In astronomy, the altitude of a celestial object is its Angular Distance above or below the celestial
horizon.
the diameter of a telescope's primary lens or mirror; the larger the aperture, the greater the
telescope's light-gathering power.
A measure of the relative brightness of a star or other celestial object as perceived by an observer on
Earth.
A unit of angular size equal to 1/60 of a degree.
A unit of angular size equal to 1/3,600 of a degree (or 1/60 of an arcminute).
A small unofficial grouping of stars in the night sky.
A small, rocky body that orbits a star.
The pseudoscientific belief that the positions of stars and planets exert an influence on human
affairs; astrology has nothing in common with astronomy
The distance between the Earth and the Sun. It is equal to 149,597,900 km., usually rounded off to
150,000,000 km.
The emission of light when charged particles from the solar wind slams into and excites atoms and
molecules in a planet's upper atmosphere.
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. .
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.
The projection of the Earth's equator on to the celestial sphere. It divides the sky into two equal
hemispheres.
The imaginary projection of Earth's rotational axis north or south pole onto the celestial sphere.
An imaginary sphere surrounding the Earth, concentric with the Earth's center.
The act of putting a telescope's optics into perfect alignment.
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.
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".
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.
38
FFocal length
JJovian Planets
KKuiper Belt
LLight-Year (ly)
MMagnitude
Meridian
Messier
NNebula
North Celestial Pole
Nova
OOpen Cluster
PParallax
Parfocal
Parsec
Point Source
RReflector
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.
Any of the four gas giant planets that are at a greater distance form the sun than the terrestrial
planets.
A region beyond the orbit of Neptune extending to about 1000 AU which is a source of many short
period comets.
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).
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.
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.
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.
Interstellar cloud of gas and dust. Also refers to any celestial object that has a cloudy appearance.
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".
Although Latin for "new" it denotes a star that suddenly becomes explosively bright at the end of its
life cycle.
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.
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.
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.
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.)
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.
A telescope in which the light is collected by means of a mirror.
39
Resolution
Right Ascension: (RA)
SSidereal Rate
TTerminator
UUniverse
VVariable Star
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.
The angular distance of a celestial object measured in hours, minutes, and seconds along the
Celestial Equator eastward from the Vernal Equinox.
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.
The boundary line between the light and dark portion of the moon or a planet.
The totality of astronomical things, events, relations and energies capable of being described
objectively.
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.
WWaning Moon
Waxing Moon
The period of the moon's cycle between full and new, when its illuminated portion is decreasing.
The period of the moon's cycle between new and full, when its illuminated portion is increasing.
ZZenith
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.
40
Appendix C – Maps of Time Zones
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48
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 2001 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
11-01
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