Celestron CGEM 925, CGEM 800, CGEM 1100 User Manual

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INSTRUCTION MANUAL

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CCGGEEMM88000

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CCGGEEMM99225

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CCGGEEMM1111000

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

Warning.......................................................................................................................................................................................................... 4

ASSEMBLY................................................................................................................................................................................................................................. 6

Setting up the Tripod...................................................................................................................................................................................... 6

Attaching the Equatorial Mount..................................................................................................................................................................... 7

Attaching the Accessory Tray........................................................................................................................................................................ 8

Installing the Counterweight Bar.................................................................................................................................................................... 8

Installing the Counterweight.......................................................................................................................................................................... 8

Attaching the Hand Control Holder ............................................................................................................................................................... 9

Attaching the Optical Tube to the Mount....................................................................................................................................................... 9

Attaching the Visual Back............................................................................................................................................................................ 10

Installing the Star Diagonal.......................................................................................................................................................................... 10

Installing the Eyepiece................................................................................................................................................................................. 10

Installing the Finderscope ............................................................................................................................................................................ 11

Installing the CGEM 1100 Finderscope....................................................................................................................................................... 11

Removing the Lens Cap............................................................................................................................................................................... 13

Moving the Telescope Manually.................................................................................................................................................................. 13

Balancing the Mount in R.A......................................................................................................................................................................... 13

Balancing the Mount in DEC....................................................................................................................................................................... 14

Adjusting the Mount .................................................................................................................................................................................... 14

Adjusting the Mount in Altitude................................................................................................................................................................... 14

Adjusting the Mount in Azimuth.................................................................................................................................................................. 15

Powering the Telescope ............................................................................................................................................................................... 15

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

Hand Control Operation ............................................................................................................................................................................... 17

Alignment Procedures.................................................................................................................................................................................. 17

Startup Procedure......................................................................................................................................................................................... 18

Two Star Align............................................................................................................................................................................................. 19

East/West Filtering.............................................................................................................................................................................. 19

Quick-Align ................................................................................................................................................................................................. 20

Last Alignment............................................................................................................................................................................................. 21

Re-Alignment............................................................................................................................................................................................... 21

Object Catalog.............................................................................................................................................................................................. 21

Selecting an Object....................................................................................................................................................................................... 21

Slewing to an Object .................................................................................................................................................................................... 22

Finding Planets............................................................................................................................................................................................. 22

Tour Mode.................................................................................................................................................................................................... 22

Constellation Tour........................................................................................................................................................................................ 22

Direction Buttons.......................................................................................................................................................................................... 23

Rate Button................................................................................................................................................................................................... 23

Setup Procedures.......................................................................................................................................................................................... 23

Tracking Mode.................................................................................................................................................................................... 23

Tracking Rate...................................................................................................................................................................................... 24

Date/Time............................................................................................................................................................................................24

User Defined Objects .......................................................................................................................................................................... 24

Get RA/DEC ....................................................................................................................................................................................... 25

Goto R.A/Dec......................................................................................................................................................................................25

Identify................................................................................................................................................................................................ 25

Precise GoTo................................................................................................................................................................................................ 25

Scope Setup Features.................................................................................................................................................................................... 25

Setup Time-Site...................................................................................................................................................................................25

Anti-backlash ...................................................................................................................................................................................... 26

Filter Limits.........................................................................................................................................................................................26

Direction Buttons ................................................................................................................................................................................26

Goto Approach.................................................................................................................................................................................... 26

Autoguide Rates.................................................................................................................................................................................. 27

OTA Orientation..................................................................................................................................................................................27

Meridian.............................................................................................................................................................................................. 27

Mount Settings ....................................................................................................................................................................................27

RA Limits............................................................................................................................................................................................ 28

Utility Features............................................................................................................................................................................................. 28

Calibrate Mount................................................................................................................................................................................... 28

Home Position..................................................................................................................................................................................... 29

Light Control.......................................................................................................................................................................................29

Factory Settings...................................................................................................................................................................................29

Version................................................................................................................................................................................................ 29

Get Axis Position.................................................................................................................................................................................29

Goto Axis Position .............................................................................................................................................................................. 29

Hibernate.............................................................................................................................................................................................29

Sun Menu ............................................................................................................................................................................................29

Scrolling Menu.................................................................................................................................................................................... 30

Set Mount Position..............................................................................................................................................................................30

Set Mount Position....................................................................................................................................................................................... 30

Turn On/Off GPS ................................................................................................................................................................................ 30

Turn On/Off RTC................................................................................................................................................................................30

Periodic Error Correction ....................................................................................................................................................................30

TELESCOPE BASICS.............................................................................................................................................................................................................. 32

Image Orientation......................................................................................................................................................................................... 32

Focusing....................................................................................................................................................................................................... 33

Calculating Magnification............................................................................................................................................................................ 33

Determining Field of View........................................................................................................................................................................... 33

General Observing Hints.............................................................................................................................................................................. 34

ASTRONOMY BASICS........................................................................................................................................................................................................... 35

The Celestial Coordinate System.................................................................................................................................................................. 35

Motion of the Stars....................................................................................................................................................................................... 36

Polar Aligning the Mount............................................................................................................................................................................. 37

Polar Align ..........................................................................................................................................................................................37

Finding the North Celestial Pole................................................................................................................................................................... 39

CELESTIAL OBSERVING ..................................................................................................................................................................................................... 40

Observing the Moon..................................................................................................................................................................................... 40

Lunar Observing Hints ................................................................................................................................................................................. 40

Observing the Planets................................................................................................................................................................................... 40

Observing the Sun ........................................................................................................................................................................................ 40

Solar Observing Hints .................................................................................................................................................................................. 41

Observing Deep Sky Objects........................................................................................................................................................................ 41

Seeing Conditions......................................................................................................................................................................................... 41

Transparency................................................................................................................................................................................................ 41

Sky Illumination........................................................................................................................................................................................... 41

Seeing........................................................................................................................................................................................................... 41

ASTROPHOTOGRAPHY........................................................................................................................................................................................................ 43

Short Exposure Prime Focus Photography................................................................................................................................................... 43

Eyepiece Projection...................................................................................................................................................................................... 44

Long Exposure Prime Focus Photography ................................................................................................................................................... 46

Periodic Error Correction (PEC) .................................................................................................................................................................. 47

Using Periodic Error Correction................................................................................................................................................................... 47

Terrestrial Photography................................................................................................................................................................................ 48

Metering....................................................................................................................................................................................................... 48

Reducing Vibration ...................................................................................................................................................................................... 48

CCD Imaging ............................................................................................................................................................................................... 49

Auto Guiding................................................................................................................................................................................................ 49

TELESCOPE MAINTENANCE.............................................................................................................................................................................................. 50

Care and Cleaning of the Optics................................................................................................................................................................... 50

Collimation................................................................................................................................................................................................... 50

OPTIONAL ACCESSORIES................................................................................................................................................................................................. 53

APPENDIX A – TECHNICAL SPECIFICATIONS............................................................................................................................................................ 56

APPENDIX B – GLOSSARY OF TERMS............................................................................................................................................................................ 57

APPENDIX C – RS-232 CONNECTION................................................................................................................................................................................ 60

APPENDIX D – TIME ZONE MAP........................................................................................................................................................................................ 62

SKY MAPS ................................................................................................................................................................................................................................ 64

Congratulations on your purchase of the Celestron CGEM Series telescope! The CGEM Series is made of the highest quality materials to ensure stability and durability. All this adds up to a telescope that gives you a lifetime of pleasure with a minimal amount of maintenance. Furthermore, your Celestron telescope is versatile — it will grow as your interest grows.

The CGEM Series ushers in the next generation of computer automated telescopes. The CGEM series continues in this proud tradition combining large aperture optics with the sophistication and ease of use of our computerized GoTo mount.

If you are new to astronomy, you may wish to start off by using the built-in Sky Tour feature, which commands the telescopes 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 40,000 objects, including customized lists of all the best deep-sky objects, bright double stars and variable stars. No matter your level of experience, the CGEM Series telescopes will unfold for you and your friends all the wonders of the Universe.

Some of the many standard features of the telescope include:

• Fully enclosed optical encoders for position location.

• Ergonomically designed mount that disassembles into compact and portable pieces.

• Database filter limits for creating custom object lists.

• Storage for programmable user defined objects; and Many other high performance features! The CGEM deluxe features combine with Celestron’s legendary Schmidt-Cassegrain optical system to give amateur astronomers 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 telescope, so you should keep this manual handy until you have fully mastered your telescope’s operation. The 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 telescope is designed to give you years of fun and rewarding observations. However, there are a few things to consider before using your telescope that will ensure your safety and protect your equipment.

Warning

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

filter). Permanent and irreversible eye damage may result.

 Never use your telescope to project an image of the sun onto any surface. Internal heat build-up can damage the telescope and any

accessories attached to it.

 Never use an eyepiece solar filter or a Herschel wedge. Internal heat build-up inside the telescope can cause these devices to crack or

break, allowing unfiltered sunlight to pass through to the eye. Never leave the telescope unsupervised, either when children are present or adults who may not be familiar with the correct operating procedures of your telescope

Figure 2.2 – CGEM

(CGEM 1100 Shown)

1 Optical Tube 7 Tripod Center Leg Brace/Accessory Tray 2 Telescope Mounting Platform 8 Counterweight(s) 3 Equatorial Mount 9 Counterweight Bar 4 Latitude Adjustment Knob 10 Azimuth Adjustment Knob 5 Hand Control 11 Dovetail Mounting Bar 6 Tripod 12 Schmidt Corrector Lens

CONTROL PANEL C Hand Control Port A On/Off Switch D Aux Port B 12v Input Jack E Autoguider Port

This section covers the assembly instructions for your Celestron Telescope. Your telescope should be set up indoor the first

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time so that it is easy to identify the various parts and familiarize yourself with the correct assembly procedure before attempting it outdoor.

CGEM 800 CGEM 925 CGEM 1100

Diameter

Focal Length

Eyepiece

Finderscope

Diagonal

Mount Tripod

Software

Counterweights

203mm (8") Schmidt-

Cassegrain

2032mm F/10 2350mm F/10 2800mm F/10

25mm - 1.25" (81x) 25mm - 1.25" (94x) 40mm - 1.25" (70x)

6x30 6x30 9x50

90° - 1.25" 90° - 1.25" 90° - 1.25"

CGEM Equatorial CGEM Equatorial CGEM Equatorial

2" Stainless Steel 2" Stainless Steel 2" Stainless Steel

NexRemote Telescope

Control Software

1-17lb

The Celestron CGEM Series telescopes are shipped in three main boxes. In separate boxes are the following:

 Optical Tube Assembly and Standard Accessories  Equatorial Mount with Hand Control, and Counterweight Bar  Tripod plus one Counterweight

 Additional Counterweights (11098 & 11099 only)

235mm (9.25") Schmidt-

Cassegrain

NexRemote Telescope Control Software

1-17lb; 1-11lb 2-17lb

280mm (11") Schmidt-

NexRemote Telescope

Cassegrain

Control Software

Remove all the pieces from their respective boxes and place on a flat, clear work area. A large floor space is ideal. When setting up your Celestron telescope you must start with the tripod and work up from there. These instructions are laid out in the order each task must be performed.

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The CGEM tripod comes with an all metal center leg brace / accessory tray to give rock solid support to the mount. The tripod comes fully assembled with a metal plate, called the tripod head, that holds the legs together at the top. In addition, there is a central rod that extends down from the tripod head that attaches the equatorial mount to the tripod. To set up the tripod:

1. Stand the tripod upright and pull the tripod legs apart until each leg is fully extended. The tripod will now stand by itself. Once the tripod is set up, you can adjust the height at which it stands.

2. Loosen the lever on the leg clamp so that the tripod leg can be adjusted.

3. Slide the center portion of the tripod leg away from the tripod head until it is at the desired height.

4. Tighten the levers on each leg clamp to hold the legs in place.

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To ensure safe shipment of your CGEM mount, the Azimuth Adjustment Knobs have been removed from the mount and will need to be attached.

Before securing the mount to the tripod as shown in Fig. 2-3:

1. Locate the Azimuth Adjustment Knobs from the box containing the CGEM mount.

2. Thread one knob into each of the holes located on either side of the mount.

3. Only thread the knobs about half way in, leaving enough space for the tripod Alignment Peg which will need to fit between the screw tips.

Figure 2-2

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The equatorial mount allows you to tilt the telescope’s axis of rotation so that you can track the stars as they move across the sky. The CGEM mount is a German equatorial mount that attaches to the tripod head. On one side of the tripod head there is a metal alignment peg for aligning the mount. This side of the tripod will face north when setting up for an astronomical observing session. To attach the equatorial head:

1. Locate the azimuth adjustment screws on the equatorial mount.

2. Retract the screws so they do not extend into the azimuth housing on the mount.

Do NOT remove the screws since they are needed later

for polar alignment.

3. Hold the equatorial mount over the tripod head so that the azimuth housing is above the metal peg.

4. Place the equatorial mount on the tripod head so that the two are flush.

5. Tighten the knob (attached to the central rod) on the underside of the tripod head to hold the equatorial mount firmly in place.

Point Towards North

Equatorial

Mount

Azimuth Adjustment Screws

Alignment Peg

Mounting

Knob

Figure 2-3

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Counterweight

Safety Screw

Counterweight

Bar

Locking Screw

1. Slide the accessory tray over the central rod so that each arm of the tray is pushing against the inside of the tripod legs.

2. Thread the accessory tray knob on to the central rod and tighten.

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To properly balance the telescope, the mount comes with a counterweight bar and at least one counterweight (depending on model). To install the counterweight bar:

1. Locate the counterweight bar locking nut from the box containing the CGEM mount (see Fig 2-5).

2. Thread the counterweight bar through the rounded end of locking nut until the threads pass all the way through and the locking nut can go no further.

3. Locate the opening in the equatorial mount on the DEC axis

4. Thread the counterweight bar into the opening until tight.

5. Tighten the counterweight bar lock nut fully for added support.

Once the bar is securely in place you are ready to attach the counterweight.

Since the fully assembled telescope can be quite heavy, position the mount so that the polar axis is pointing towards north before the tube assembly and counterweights are attached. This will make the polar alignment procedure much easier.

Mounting Knob

Central Rod

Accessory Tray

Accessory Tray Knob

Figure 2-4

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Depending on which telescope model you have, you will receive either one, two or three counterweights. To install the counterweight(s):

1. Orient the mount so that the counterweight bar points toward the ground .

2. Remove the counterweight safety screw on the end of the counterweight bar (i.e., opposite the end that attaches to the mount).

3. Loosen the locking screw on the side of the counterweight.

4. Slide the counterweight onto the shaft (see Figure 2-5).

5. Tighten the locking screw on the side of the weight to hold the counterweight in place.

6. Replace the counterweight safety screw.

Counterweight Bar

Locking Nut

Figure 2-5 – Mount shown with two

counterweights (CGEM 925 & 1100)

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Safety Screw

Dovetail Bar

The telescope comes with a hand control holder to place the computerized hand control. The hand control holder comes in two pieces: the leg clamp that snaps around the tripod leg and the holder which attaches to the leg clamp. To attach the hand control holder:

1. Place the leg clamp up against one of the tripod legs and press firmly until the clamp wraps around the leg.

2. Slide the back of the hand control holder downward into the channel on the front of the legs clamp (see Fig 2-6) until it snaps into place.

Hand Control Holder

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The telescope attaches to the mount via a dovetail slide bar which is mounted along the bottom of the telescope tube

attach the optical tube, make sure that the declination and right ascension clutch knobs are tight (see Figure 2-13) and the counterweight(s) are securely installed.

telescope. To mount the telescope tube:

Now that the optical tube is securely in place, the visual accessories can now be attached to the telescope.

1. Loosen the mounting screw on the side of the telescope mounting platform. This allows you to slide the dovetail bar onto the mount.

2. Remove the safety screw located at the front of the dovetail bar.

3. Slide the dovetail bar on the telescope tube into the mounting platform of the mount. Slide the telescope so that the back of the dovetail bar is close to the back of the mounting platform.

4. Tighten the mounting screw on the side of the mounting platform to hold the telescope in place.

Leg Clamp

. Before you

This will ensure that the mount does not move suddenly while attaching the

Figure 2-6

Telescope Mounting Screw

Figure 2-7

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Star Diagonal

The visual back is the accessory that allows you to attach all visual accessories to the telescope. The telescope optical tubes come with the visual back installed. If it is not already on the tube it can be attached as follows:

1. Remove the rubber cover on the rear cell.

2. Place the knurled slip ring on the visual back over the threads on the rear cell (Fig 2-8).

3. Hold the visual back with the set screw in a convenient position and rotate the knurled slip ring clockwise until tight.

Once this is done, you are ready to attach other accessories, such as eyepieces, diagonal prisms, etc.

If you want to remove the visual back, rotate the slip ring counterclockwise until it is free of the rear cell.

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The star diagonal is a prism that diverts the light at a right angle to the light path of the telescope. This allows you to observe in positions that are physically more comfortable than if you looked straight through. To attach the star diagonal onto the optical tube:

1. Turn the set screw on the visual back until its tip no longer extends into (i.e., obstructs) the inner diameter of the visual back.

2. Slide the chrome portion of the star diagonal into the visual back.

3. Tighten the set screw on the visual back to hold the star diagonal in place.

If you wish to change the orientation of the star diagonal, loosen the set screw on the visual back until the star diagonal rotates freely. Rotate the diagonal to the desired position and tighten the set screw.

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The eyepiece, or ocular, is an optical element that magnifies the image focused by the telescope. The eyepiece fits into either the visual back directly or the star diagonal. To install an eyepiece:

1. Loosen the set screw on the star diagonal until the tip no longer extends into the inner diameter of the eyepiece end of the diagonal.

Eyepiece

Visual Back

Figure 2-8

2. Slide the chrome portion of the eyepiece into the star diagonal.

3. Tighten the set screw on the star diagonal to hold the eyepiece in place.

To remove the eyepiece, loosen the set screw on the star diagonal and slide the eyepiece out. You can replace it with another eyepiece (purchased separately).

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 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.”

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Rear Cell

The CGEM 800 and 925 telescopes come with a 6x30 finderscope used to help you locate and center objects in the main field of your telescope. To accomplish this, the finder has a built-in cross-hair reticle that shows the optical center of the finderscope. The CGEM 1100 comes with a 9x50 finderscope.

Start by removing the finder and hardware from the plastic wrapper. Included are the following:

• Finderscope

• Finder Bracket

• Rubber O-ring

• Three Nylon Thumbscrews (10-24x1/2")

• Two Phillips Head Screws (8-32x1/2")

To install the finderscope:

1. Attach the bracket to the optical tube. To do this, place the curved

portion of the bracket with the slot over the two holes in the rear cell. The bracket should be oriented so that the rings that hold the finder are over the telescope tube, not the rear cell (see Fig 2-9). Start threading the screws in by hand and tighten fully with an Allen wrench.

2. Partially thread-in the three nylon thumbscrews that hold the finder

in place inside the bracket. Tighten the screws until the nylon heads are flush with the inner diameter of the bracket ring. Do NOT thread them in completely or they will interfere with the placement of the finder. (Having the screws in place when the finder is installed will be easier than trying to insert the screws after the finder has been installed.)

3. Slide the rubber O-ring over the back of the finder (it will NOT fit over the

objective end of the finder). It may need to be stretched a little. Once on the main body of the finder, slide it up about one inch from the end of the finder.

4. Rotate the finder until one cross hair is parallel to the R.A. axis and the other is parallel to the DEC axis.

5. Slide the eyepiece end of the finder into the front of the bracket.

6. Slightly tighten the three nylon thumbscrews on the front ring of the bracket to hold the finder in place.

7. Once on, push the finder back until the O-ring is snug inside the back ring of the finder bracket.

Figure 2-11

Finderscope

Nylon Adjustment Screw

Finder Bracket

Figure 2-9

8. Hand tighten the three nylon tipped thumbscrews until snug.

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The CGEM 1100 telescope comes with a 9x50 finderscope. The specifications for a finderscope stand for the magnification and the aperture, in millimeters, of the scope. So, a 9x50 finder magnifies objects eight times and has a 50mm objective lens.

Finderscope Installation

The finderscope must first be mounted in the included quick-release bracket then attached to the rear cell of the telescope. To install the finderscope:

1. Locate the finderscope mounting bracket attached to the bottom portion of the finder bracket. Loosen the two thumb screws to slide the mounting bracket from the finderscope bracket.

2. Find the two holes in the rear cell of the telescope on the top left, when looking from the back of the tube.

3. Place the mounting bracket over the two holes of the rear cell as shown in the figure 2-10.

Figure

2-10

Pivot

4. Insert the screws through the bracket and into the rear cell.

WARNING: If you remove the mounting bracket, do not completely thread the screws back into the rear cell of the telescope. The screws may be long enough to obstruct the movement of, and possibly damage the primary mirror.

Alignment Screws

With the bracket firmly attached to the telescope, you are ready to attach the finder to the bracket.

1. Slide the O-Ring over the back of the finderscope

Scr

and position it on the tube toward the objective end of the finderscope.

2. Slide the eyepiece end of the finderscope into the front ring of the bracket (the front ring is the one without the adjustment screws), then through the back ring. It may be necessary to push down the spring loaded pivot screw so that the finder will pass through the back ring (see figure 2-11)

Figure 2-11

3. Push the finder back until the O-Ring is snug inside the front ring of the finder bracket.

4. Hand tighten the two alignment thumb screws until they make contact with the finderscope.

The finderscope bracket comes in two pieces; the mounting bracket (left) and the finder bracket (right)

Figure 2-12

Quick release Screws

Aligning the Finderscope

The finderscope is adjusted using two adjustment screws, located on the top and on the right (when looking though the finder) of the finder bracket and a spring loaded pivot screw (located on the left side of the bracket). This allows you to turn the top adjustment screw to move the finderscope up and down, and turn the right adjustment screw to move the finderscope right to left. The spring loaded pivot screw puts constant pressure on the finder so that the adjustment screws are always making contact with the finder.

To make the alignment process a little easier, you should perform this task in the daytime when it is easier to locate objects in the telescope without the finder. To align the finder:

1. Choose a conspicuous object that is in excess of one mile away. This will eliminate any possible parallax effect between the telescope and the finder.

2. Point your telescope at the object you selected and center it in the main optics of the telescope.

Declination

Lock

Right Ascension

(RA) Lock

3. Lock the azimuth and altitude clamps to hold the telescope in place.

4. Check the finder to see where the object is located in the field of view.

5. Adjust the thumb screws on the finder bracket, until the cross hairs are centered on the target.

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The 8, 9.25 and 11" lens cap utilizes a bayonet-type locking mechanism to hold it in place. To remove the lens cap, hold the cover firmly and rotate the outer edge 1/2” counterclockwise and pull off.

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In order to properly balance your telescope, you will need to move your telescope manually at various portions of the sky to observe different objects. To make rough adjustments, loosen the R.A. and DEC clutch knobs slightly and move the telescope in the desired direction.

Both the R.A. and DEC axis have lock levers to clutch down each axis of the telescope. To loosen the clutches on the telescope, rotate the lock levers counterclockwise.

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To eliminate undue stress on the mount, the telescope should be properly balanced around the polar axis. Proper balancing is crucial for accurate tracking. To balance the mount:

Figure 2-13

1. Verify that the telescope is securely attached to the telescope mounting platform.

2. Loosen the R.A. lock lever and position the telescope off to one side of the mount. The counterweight bar will

extend horizontally on the opposite side of the mount.

3. Release the telescope — GRADUALLY — to see which way the telescope “rolls.”

4. Loosen the set screws on the side of the counterweight so it can be moved the length of the counterweight bar.

5. Move the counterweight to a point where it balances the telescope (i.e., the telescope remains stationary when the

R.A. clutch knobs are loose).

6. Tighten the screw on the counterweight to hold it in place.

While the above instructions describe a perfect balance arrangement, there should be a SLIGHT imbalance to ensure the best possible tracking. When the scope is on the west side of the mount the counterweight should be slightly imbalanced to the counterweight bar side. And when the tube is on the east side of the mount there should be a slight imbalance toward the telescope side. This is done so that the worm gear is pushing against a slight load. The amount of the imbalance is very slight. When taking astrophotographs, this balance process can be done for the specific area at which the telescope is pointing to further optimize tracking accuracy.

Figure 2-14

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Although the telescope does not track in declination, the telescope should also be balanced in this axis to prevent any sudden motions when the DEC lock lever is loose. To balance the telescope in DEC:

1. Loosen the R.A. clutch lock lever and rotate the telescope so that it is on one side of the mount (i.e., as described

in the previous section on “Balancing the Mount in R.A.”).

2. Tighten the R.A. lock lever to hold the telescope in place.

3. Loosen the DEC clutch lock lever and rotate the telescope until the tube is parallel to the ground.

4. Release the tube —

GO OF THE TELESCOPE TUBE COMPLETELY!

5. Slightly loosen the knobs that holds the telescope to the mounting platform and slide the telescope either forward

or backward until it remains stationary when the DEC clutch is loose. Do NOT let go of the telescope tube while the knob on the mounting platform is loose. It may be necessary to rotate the telescope so that the counterweight bar is pointing down before loosening the mounting platform screw.

6. Tighten the knobs on the telescope mounting platform to hold the telescope in place.

Like R.A. balance, these are general balance instructions and will reduce undue stress on the mount. When taking astrophotographs, this balance process should be done for the specific area at which the telescope is pointing.

GRADUALLY — to see which way it rotates around the declination axis. DO NOT LET

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In order for a motor drive to track accurately, the telescope’s axis of rotation must be parallel to the Earth’s axis of rotation, a process known as polar alignment. Polar alignment is achieved NOT by moving the telescope in R.A. or DEC, but by adjusting the mount vertically, which is called altitude, and horizontally, which is called azimuth. This section simply covers the correct movement of the telescope during the polar alignment process. The actual process of polar alignment, that is making the telescope’s axis of rotation parallel to the Earth’s, is described later in this manual in the section on “

Alignment.”

Adjusting the Mount in Altitude

• To increase (raise) the latitude of the polar axis, turn the rear latitude adjustment knob and loosen the front screw (if necessary).

• To decrease (lower) the latitude of the polar axis, turn the rear latitude adjustment knob and tighten the front screw (if necessary).

Rear Latitude

Adjustment

Knob

Azimuth Adjustment Knob

Figure 2-15

Polar

Front Latitude Adjustment Screw

The latitude adjustment on the mount has a range from approximately 15° to 70°.

It is best to always make final adjustments in latitude by moving the mount against gravity (i.e. using the rear latitude adjustment screw to raise the mount).

Adjusting the Mount in Azimuth

For rough adjustments in azimuth, simply pick up the telescope and tripod and move it side to side until it is roughly pointing towards north. For fine adjustments in azimuth:

1. Turn the azimuth adjustment knobs located on either side of the azimuth housing (see Fig 2-15). While standing behind the telescope, the knobs are on the front of the mount.

• Turning the right adjustment knob clockwise moves the mount toward the right.

• Turning the left adjustment knob clockwise moves the mount to the left.

Both screws push off of the peg on the tripod head, which means you may have to loosen one screw while tightening the other. The screw that holds the equatorial mount to the tripod may have to be loosened slightly.

Keep in mind that adjusting the mount is done during the polar alignment process only. Once polar aligned, the mount must NOT be moved. Pointing the telescope is done by moving the mount in right ascension and declination, as described earlier in this manual.

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The telescope mount can be powered by the supplied car battery adapter or optional 12v AC adapter. Use only adapters supplied by Celestron. Using any other adapter may damage the electronics or cause the telescope not to operate properly, and will void your manufacturer's warranty.

1. To power the telescope with the car battery adapter (or 12v AC adapter), simply plug the round post into the 12v outlet on the electronic panel and plug the other end into your cars cigarette lighter outlet or portable power supply (see

Optional Accessories).

2. Turn on the power to the telescope by flipping the switch, located on the electronics panel, to the "On" position.

All Celestron computerized telescope come with a hand control designed to give you instant access to all the functions that

Figure 3

your telescope has to offer. With automatic slewing to over 40,000 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 computerized hand controller:

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 telescope to use a selected star or object as an alignment position.

Direction Keys: Allows complete control of the telescope in any direction. Use the direction keys to move the telescope to the initial alignment stars or for centering objects in the eyepiece.

The Hand Control

4. Catalog Keys: The hand control has keys on the hand control to allow direct access to each of the catalogs in its database. The hand control contains the following catalogs in its database:

Messier – Complete list of all Messier objects. NGC – Complete list of all the deep-sky objects in the Revised New General Catalog. Caldwell – A combination of the best NGC and IC objects. Planets - All 8 planets in our Solar System plus the 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 telescope's database have been broken

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

Named Stars

Named Objects

Double Stars

Variable Stars

Asterisms

CCD Objects

IC Objects

Abell Objects

Constellation

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

Tour: Activates the tour mode, which seeks out all the best objects for the current date and time, and automatically slews the telescope to those objects. Enter: Pressing Enter allows you to select any of the telescope's functions and accept entered parameters.

Undo: Undo will take you out of the current menu and display the previous level of the menu path. Press Undo repeatedly to get back to a main menu or use it to erase data entered by mistake.

Menu: Displays the many setup and utilities functions such as tracking rates 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 will appear on the right side of the LCD when there are sub-menus below the displayed menu. Using these keys will scroll through those sub-menus. Rate: Instantly changes the rate of speed of the motors when the direction buttons are pressed.

11.

12.

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

Common name listing of the brightest stars in the sky. Alphabetical listing of over 50 of the most popular deep sky objects. Numeric-alphabetical listing of the most visually stunning double, triple and quadruple stars in the sky. Select list of the brightest variable stars with the shortest period of changing magnitude. A unique list of some of the most recognizable star patterns in the sky A custom list of many interesting galaxy pairs, trios and clusters that are well suited for CCD imaging. A complete list of all the Index Catalog deep-sky objects. A custom list of the Abell Catalog deep-sky galaxies. A complete list of all 88 constellations.

Hand Control Operation

This section describes the basic hand control procedures needed to operate all Celestron computerized telescopes. These procedures are grouped into three categories: Alignment, Setup and Utilities. The alignment section deals with the initial telescope alignment as well as finding objects in the sky; the setup section discusses changing parameters such as tracking mode and tracking rate; finally, the last section reviews all of the utilities functions such as calibrating your mount, polar alignment and backlash compensation.

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In order for the telescope to accurately point to objects in the sky, it must first be aligned with 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. There are many ways to align your telescope with the sky depending on what information the user is able to provide:

Two Star Align uses the entered time/location information and allows the user to select which two alignment stars

the telescope will automatically slew to. One Star Align uses the same time/location information but only uses one star for

Figure 3

-2-

Declination In

dex Marks and Right Ascension (RA) I ndex Marks

alignment. telescope.

Solar System Align will display a list of visible daytime objects (planets and the moon) available to align the

Quick-Align will ask you to input all the same information as you would for the Auto Align procedure. However,

instead of slewing to the alignment stars for centering and alignment, the telescope bypasses this step and simply models the sky based on the information given. Finally,

Last Alignment restores your last saved star alignment and switch position.

Last Alignment also serves as a good safeguard in case the telescope should lose power.

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Before any of the described alignments are performed, the telescope mount needs to be positioned so that the index marks are aligned on both the right ascension and declination axes. (see Fig 3-2).

Once the index position has been set, the hand control will display the last entered date and time information stored in the hand control.

Index

Marks

1. Press ENTER to begin the alignment process.

2. The hand control will ask the user to set the mount to its index position. Move the telescope mount, either manually or with the hand control, so that the index marked in both R.A. and Dec are aligned (see Fig 3-2). Press

Enter to

continue.

 The hand control will then display the

last entered local time, time zone and date.

 Use the Up/Down keys (10) to view the

current parameters.

 Press ENTER to accept the current parameters.  Press UNDO to enter current date, time and location information into the hand control. The following

information will be displayed:

Location - The hand control 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 locations, use the Up or Down scroll key to select

 Use the Up and Down Scroll buttons to choose your current state (or country if International locations was

Internationaland press ENTER.

United States is displayed. For international

selected) from the alphabetical listing and press ENTER.

 Use the Up and Down Scroll buttons to choose the closest city to your location from the displayed list and

press ENTER.

Time - Enter the current local time for your area. You can enter either the local time (i.e. 08:00), or you can enter military time (i.e.

 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

20:00 ).

between options.

 Select the time zone that you are observing from. Again, use the Up and Down buttons (10) to scroll through

Updating Your

Location

the choices. Refer to Time Zone map in Appendix for more information.

Date - Enter the month, day and year of your observing session.

- Since you may not need to update your observing location as often as the date and time, it

is not displayed each time you update the date and time. To update your city, press UNDO at any time when updating

your date and time. Continue to press UNDO to change the state, country or to add longitude/latitude coordinates.

Select one of the alignment methods as described below.

Note: If incorrect information is entered into the hand control, the UNDO button acts like a back space button allowing the user to re-enter the correct data.

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Two-Star Align allows the user to select two stars on which to align the telescope. To align your telescope using the Two-Star Align method:

1. Select Two-Star Align from the alignment choices given. Based on the date and time information entered, the hand control will automatically select and display a bright star that is above the horizon.

 Press ENTER to select this star as your first alignment star.  If for some reason the chosen star is not visible (perhaps behind a tree or building) press UNDO to have the

hand control automatically select the next brightest star.

 Or you can use the Up/Down keys to browse the entire Named Star list and select any one of over two hundred

alignment stars.

2. Once the telescope is finished slewing to your first alignment star, the display will ask you to use the arrow buttons to align the selected star with the cross hairs in the center of the finderscope. When centered in the finder, press ENTER.

3. 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.

4. After the first alignment star has been entered the hand control will automatically

East/West (E/W) Filtering

select a second alignment star and have you repeat this procedure for that star.

When the telescope has been aligned on both stars the display will ask you if you wish to add additional calibration stars. Calibration stars are used to improve the pointing accuracy of your telescope by compensating for subtle opto-mechanical misalignments between the telescope optics and the mount. Therefore it is usually a good idea to add at least one additional calibration star to improve the telescope’s all-sky pointing accuracy.

5. Press ENTER to select a calibration star. Select a star the same way you did with the first two alignments stars and pres ENTER. You will notice that all the calibration stars displayed are located on the opposite side of the side of the sky (Meridian) as the original alignment stars. This is essential for an accurate calibration of the mount.

Finally you can chose to continue to add additional calibration stars or Press UNDO to complete the alignment.

Tips for adding calibration stars:

 Although for casual observing it is not necessary to add calibration stars, it

is recommended that you add as many as three calibration stars for optimal

In order to ensure the best possible full sky pointing accuracy, your computerized telescope automatically filters and chooses its initial alignment stars so that the first two alignment stars are located on one side of the Meridian and any calibration stars are on the opposite side of the Meridian, as indicated by the "W" or "E" displayed in the upper-right corner of the LCD. East/West filtering can be changed simply by pressing the MENU button at any time during the alignment process.

point accuracy.

 Calibration stars that are near the equator offer the best results than stars near the poles.

 Although it is not be necessary to use calibration stars if the telescope mount has not been moved since its

original alignment/calibration, it may be necessary to recalibrate the telescope if the optical tube has been removed for any reason.

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Figure

3-3

One-Star Alignment works much the same way as Two-Star Align but uses only a single star in the sky for alignment. This method of alignment is not as accurate as the two-star alignment and is recommended only for telescopes that are permanently and accurately polar aligned.

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Solar System Align is designed to provide excellent tracking and GoTo performance by using solar system objects (Sun, Moon and planets) to align the telescope with the sky. Solar System Align is a great way to align your telescope for daytime viewing as well as a quick way to align the telescope for nighttime observing.

Never look directly at the sun with the naked eye or with a telescope (unless you have the proper solar filter). Permanent and irreversible eye damage may result.

1. Select Solar System Align from the alignment options.

2. The SELECT OBJECT message will appear in the top row of the

display. Use the Up and Down scroll keys (10) to select the daytime object (planet, moon or sun) you wish to align. Press ENTER.

3. Use the direction arrow buttons to carefully center the object in the finderscope. Press ENTER when centered.

4. Then, center the object in the eyepiece and press ALIGN.

Once in position, the telescope will model the sky based on this information and display

The Meridian is an imaginary 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.

Alignment Successful.

Tips for Using Solar System Align

 For safety purposes, the Sun will not be displayed in any of the hand control’s customer object lists unless it is

enabled from the Utilities Menu. To allow the Sun to be displayed on the hand control, do the following:

1. Press the UNDO button until the display reads “CGEM Ready”

2. Press the MENU button and use the Up and Down keys to select the Utilities menu. Press ENTER.

3. Use the UP and Down keys to select Sun Menu and press ENTER.

4. Press ENTER again to allow the Sun to appear on the hand control display.

The Sun can be removed from the display by using the same procedure as above.

 To improve the telescope pointing accuracy, you can use the Re-Align feature as described below.

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Quick-Align uses all the date and time information entered at startup to align the telescope. However, instead of slewing to the alignment stars for centering and alignment, the telescope 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 telescope the information needed to track objects in any part of the sky (depending on accuracy of polar alignment). Quick-Align is not meant to be used to accurately locate small or faint deep-sky objects or to track objects accurately for photography.

To use Quick-Align, simply select Quick Align from the alignment options and press ENTER. The telescope will automatically use the entered date/time parameters to align itself with the sky and display

NOTE: Once a Quick-Align has been done, you can use the Re-alignment feature (see below) to improve your telescopes pointing accuracy.

Alignment Successful.

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The Last Alignment method will automatically recall the last stored index positions to continue using the alignment that was saved when the telescope was last powered down. This is a useful feature should your telescope accidentally lose power or be powered down.

NOTE: Just like with Quick-Align, you can use the Re-alignment feature (see below) to improve your telescopes pointing accuracy after using the

Hibernate feature described later in this chapter.

use the

Last Alignment method. To maintain a more accurate alignment over a series of observing sessions,

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The telescopes has a re-alignment feature which allows you to replace any of the 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 on actual objects

in the sky. This will improve the pointing accuracy of your telescope without having to re-enter addition information.

 If you have used the computer assisted polar alignment method and have manually moved the mount, it may be

necessary to re-align the mount for improved pointing accuracy.

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

1. Select the desired star (or object) from the database and slew to it.

2. Carefully center the object in the eyepiece.

3. Once centered, press the UNDO button until you are at the main menu.

4. With options

5. 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. It is usually best to replace the star closest to the new object. This will space out your alignment stars across the sky.

6. Press ALIGN to make the change.

CGEM Ready displayed, press the ALIGN key on the hand control to select Alignment Stars from the list of

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Selecting an Object

Now that the telescope is properly aligned, you can choose an object from any of the catalogs in the telescope's extensive database. The hand control has a key (4) designated for each of the catalogs in its database. There are two ways to select objects from the database: scrolling through the named object lists and entering object numbers.

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, Asterisms and CCD Objects. Selecting any one of these catalogs will display a numeric-alphabetical listing of the objects under that list. Pressing the Up and Down keys (10) allows you to scroll through the catalog to the desired object.

Helpful

Hint

When scrolling through a long list of objects, holding down either the Up or Down key will allow you to scroll

through the catalog more rapidly by only displaying every fifth catalog object.

Pressing any of the other 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".

Slewing to an Object

Once the desired object is displayed on the hand control screen, choose from the following options:

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

declination, magnitude size and text information for many of the most popular objects.

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

Caution: Never slew the telescope when someone is looking into the eyepiece. The telescope can move at 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.

Finding Planets

Your telescope can locate all 8 of our solar systems planets plus the Moon. However, the hand control will only display the solar system objects that are above the horizon (or within its filter limits). To locate the planets, press the PLANET key on the hand control. The hand control will display all solar system objects that are above the horizon:

 Use the Up and Down keys to select the planet that you wish to observe.  Press INFO to access information on the displayed planet.  Press ENTER to slew to the displayed planet.

Tour Mode

The telescopes include 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 (see

Filter Limits in the Setup Procedures section of the manual). To activate the Tour mode, press the TOUR key (6)

on the hand control. The hand control 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 Up key.

Constellation Tour

In addition to the Tour Mode, your telescope has a Constellation Tour that allows the user to take a tour of all the best objects in each of the 88 constellations. Selecting above the user defined horizon (filter limits). Once a constellation is selected, you can choose from any of the database object catalogs to produce a list of all the available objects in that constellation.

 To see information and data about the displayed object, press the INFO key.  To slew to the object displayed, press ENTER.  To see the next tour object, press the Up key.

Constellation from the LIST menu will display all the constellation names that are

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Celestron CGEM 925, CGEM 800, CGEM 1100 User Manual

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