C150-HD AND G-8N NEWTONIAN INSTRUCTION MANUAL Models #31056 and #31058
T A B L E O F C O N T E N T S ▲ INTRODUCTION .................................................................................................................................................. 5 How to Use This Manual ................................................................................................................................ 6 A Word of Caution ..........................................................................................................................................
Observing the Moon ..................................................................................................................................... 40 Observing the Planets ................................................................................................................................... 40 Observing the Sun ......................................................................................................................................... 41 Observing Deep-Sky Objects .............
I N T R O D U C T I O N Welcome to the Celestron world of amateur astronomy! Celestron has been providing amateur astronomers with the tools to explore the universe for more than a quarter of a century. The Celestron Newtonian telescope continues in this proud tradition. With a mirror diameter of 6", your C150-HD has almost 500 times the light gathering power of the unaided human eye. The G-8N, with its 8" diameter mirror gathers almost 800 times the light of your eye.
How to Use this Manual This manual is designed to instruct you in the proper use of your Celestron Newtonian telescope. The instructions are for assembly, initial use, long term operation, and maintenance. There are seven major sections to the manual. The first section covers the proper procedure for setting up your Celestron telescope. This includes setting up the tripod, attaching the telescope to the mount, balancing the telescope, etc. The second section deals with the basics of telescope use.
FAMILIAR WITH THE CORRECT OPERATING PROCEDURES OF YOUR TELESCOPE. NEVER USE AN EYEPIECE SOLAR FILTER OR A HERSCHEL WEDGE SOLAR FILTER. INTERNAL HEAT BUILD-UP INSIDE THE TELESCOPE CAN CAUSE THESE DEVICES TO CRACK OR BREAK. NEVER POINT YOUR TELESCOPE AT THE SUN UNLESS USING THE PROPER SOLAR FILTER. WHEN USING A SOLAR FILTER, ALWAYS COVER THE FINDER. ALTHOUGH SMALL IN APERTURE, THE FINDER HAS ENOUGH LIGHT GATHERING POWER TO POSSIBLY CAUSE PERMANENT AND IRREVERSIBLE EYE DAMAGE.
A S S E M B L I N G Y O U R N EWT O N IA N T E L E S C O P E This section covers the proper assembly instructions for your G-8N and C150-HD reflecting telescope. These telescopes are Newtonian reflector that utilize mirrors with specific focal lengths. The telescope comes on the German equatorial mount, which when properly aligned and fitted with the optional motors, will track objects as they move across the sky. Each telescope contains the following standard accessories.
The G-8N 1 2 15 3 14 4 13 12 5 6 7 8 10 9 Figure 2-1 G-8N with CG-5 Equatorial Mount 1. Finderscope 2. Finderscope Bracket 3. Tube Ring 4. Piggyback Adapter 5. Latitude Scale 6. Latitude Adjustment Screw 7. Tripod 8. Accessory Tray 9. Tripod Leg Clamp 10. Leg Brace Assembly 11. Counterweight 12. Counterweight Shaft 13. Equatorial Mount 14. Focuser 15.
The C150-HD 1 2 15 14 3 4 13 12 5 6 7 11 10 8 9 Figure 2-1A C150-HD with CG-4 Equatorial Mount 1. FinderscopeBracket 2. Finderscope 3. Tube Ring 4. Primary Mirror (inside tube) 5. Solw Motion Cables 6. Latitude Scale 7. Latitude Adjustment Screw 8. Tripod 10 • The C150-HD 9. 10. 11. 12. 13. 14. 15.
Assembling the Equatorial Mount Setting Up the Tripod The tripod comes fully assembled with the metal plate, called the tripod head, that holds the legs together at the top. In addition, the brackets that support the accessory tray are also attached to the tripod. Stand the tripod upright and pull the tripod legs apart until the leg brace assembly for the accessory tray is fully extended (see figure 2-2). The tripod will now stand by itself.
Attaching the Accessory There are three wing bolts that hold the accessory tray to the center leg brace. Tray 1. Locate the three wing bolts. 2. Place the accessory tray over the leg brace and position it so the thread holes in the accessory tray are above the slotted holes in the bracket. 3. Insert the wing bolts up through the slotted holes in the leg brace (see figure 23). 4. Thread the wing bolts into the holes in the accessory tray. 5. Tighten the wing bolts fully.
Attaching the Equatorial The equatorial mount allows you to tilt the telescope’s axis of rotation so that you Mount can track the stars as they move across the sky. The CG-4 and CG-5 mounts are German equatorial mounts that attache to the tripod head (i.e., metal plate on the tripod). On one side of the plate there is an “N” which signifies north. This side of the tripod will face north when setting up for an astronomical observing session. Above the “N” is a peg about 3/4" high that points straight up.
Attaching the R.A. Slow Motion Knob With the mount securely in place, you are ready to attach some of the accessories (the telescope tube will be added last). Start with the Right Ascension (R.A.) slow motion knob. The R.A. slow motion knob allows you to make fine pointing adjustments in the direction the telescope is aiming (once it is attached to the mount). To install the knob: 1. Locate the hard plastic shell under the R.A. shafts. 2. Remove either of the two oval tabs by pulling tightly. 3.
Attaching the Declination Slow Motion Knob Like the R.A. slow motion knob, the DEC slow motion knob allows you to make fine pointing adjustments in the direction the telescope is pointed. The DEC slow motion knob attaches in the same manner as the R.A. knob. The shaft that the DEC slow motion knob fits over is toward the top of the mount, just below the telescope mounting platform. Once again, you have two shafts to choose from. Use the shaft that is pointing toward the ground.
Attaching the Counterweight Bar and Counterweight The last item to be mounted before the telescope tube is the counterweight bar and counterweight. Used to balanced the telescope, the counterweight bar attaches to the opposite side of the mount as the telescope. To install the counterweight bar: 1. Retract the counterweight bar lock nut by turning it counterclockwise. This will expose the threads on the end of the counterweight bar. 2. Thread the counterweight bar into the mount completely.
Attaching the Telescope to the Mount (For G-8N) Before you attach the optical tube, fully tighten the right ascension and declination clamps. This will prevent the telescope from moving suddenly once attached to the mount. 1 Locate the mounting bracket from the box containing the equatorial mount head. 2 Attach the mounting bracket to the tube rings so that the tappered (narrow) end is against the bottom of the tube rings. 3 Loosen the hand knob on the side of the CG-5 mount.
Attaching the Telescope to the Mount (For C150HD) Before you attach the optical tube, make sure that the declination and right ascension clamps are tight. The optical tube attaches to the mount via two rings that are mounted on the tube of the telescope. To mount the telescope tube: 1. Loosen the knobs on the side of the rings. This will allow you to slide the mounting rings the length of the optical tube. 2. Locate the two holes on either end of the CG-4 mounting platform. 3.
Removing the Lens Cap The G-8N lens cover has a 1-1/2" cap covering an aperture stop that is offset from the center. To utilize the aperture stop, leave the telescope cover on the front of the tube and remove only the small aperture stop cap from the front of the cover. This is useful when observing very bright objects, like the full moon. The aperture stop reduces the amount of light entering the tube resulting in better resolution.
Balancing the Telescope in DEC The telescope should also be balanced on the declination axis to prevent any sudden motions when the DEC clamp is released. To balance the telescope in DEC: 1. Release the R.A. clamp 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 telescope in R.A.). 2. Lock the R.A. clamp to hold the telescope in place. 3.
Adjusting the Mount in Altitude For the purpose of polar alignment, there are two directions in which the mount can be adjusted; vertically, which is called altitude and horizontally, which is called azimuth. There are several ways to align on the celestial pole, many of which are discussed later in this manual. This section simply covers the correct movement of the mount during the polar alignment process. To adjust the mount in altitude (i.e.
Disassembling and Transporting Your Telescope The entire telescope and mount is light enough to pick up and carry outside for a casual observing session. If, however, you want to transport your telescope to a remote observing location, you must partially disassemble it. Here’s how: 1. Remove the telescope from the equatorial mount. Return it to the shipping carton to ensure safe transportation. 2. Remove the three wing bolts that hold the accessory tray to the tripod. 3.
Installing the Finderscope To install the finderscope onto the telescope you must first mount the finderscope through the finder bracket and then attach it to the telescope. Toward the front of the telescope tube, near the focusing assembly, there is a small bracket with a set screw in it. This is where the finderscope bracket will be mounted. To install the finderscope: 1. Slide the rubber O-ring over the eyepiece end of the finderscope and roll it 2/3 of the way up the finderscope. 2.
Installing the Eyepiece The eyepiece, or ocular as it is also called, is an optical element that magnifies the image focused by the telescope. Without the eyepiece it would be impossible to use the telescope visually. The eyepiece fits directly into the eyepiece holder. To attach an ocular: 1. Loosen the set screw on the eyepiece holder so that it does not obstruct the inner diameter of the eyepiece holder. 2. Slide the chrome portion of the eyepiece into the eyepiece holder. 3.
Technical Specifications Below is pertinent technical information on your G-8N and C150-HD telescope that you may find useful. G-8N C150-HD Optical System: Newtonian Reflector Newtonian Reflector Aperture: 200mm (8") 150mm (6") Focal Length: 1000mm (40") 750mm (30") Highest Useful Power: 480x 360x Resolution (arc seconds): 0.58 .77 Light Gathering Power: 816 459 Limiting Visual Magnitude: 14 13.5 Secondary Obstruction 2.9" 2.2" % of Primary Surface Area 13.1% 13.4% f/ratio: f/5 f/5 Length: 19.75" 14.
T E L E S C O P E B A S I C S Once your telescope has been fully assembled and the accessories attached, you are ready to take a look. This section deals with basic telescope operation. Image Orientation The Newtonian optical system produces an upside down image. This will only affect your terrestrial observations. For celestial viewing, star charts can be made to match the view in the telescope by rotating the chart 180° about the center. The view through the finder is also inverted.
Focusing To focus your telescope, simply turn the focus knob located directly below the eyepiece holder (see figure 2-13). Turning the knob clockwise allows you to focus on an object that is farther than the one you are currently observing. Turning the knob counterclockwise from you allows you to focus on an object closer than the one you are currently observing.
Aligning the Finder Accurate alignment of the finder makes it easy to find objects with the telescope, especially celestial objects. To make aligning the finder as easy as possible, this procedure should be done in the daytime when it is easy to find and identify objects. The finderscope has a spring-loaded adjustment screw that puts pressure on the finderscope while the remaining screws are used to adjust the finder horizontally and vertically.
Your First Look With the telescope fully assembled and all the accessories attached you are ready for your first look. Your first look should be done in the daytime when it is easier to locate the locking clamps and slow motion adjustment knobs. This will help to familiarize you with your telescope, thus making it easier to use at night. Daytime Observing 1. Begin by finding a distant object that is fairly bright. 2. Insert a low power eyepiece (one with a large focal length) into the telescope. 3.
Nighttime Observing Looking at objects in the sky is quite different than looking at objects on Earth. For one, many objects seen in the daytime are easy to see with the naked eye and can be located by using landmarks. In addition, objects on the ground are stationary, or at least for the most part. In the night sky you will see a tremendous amount of stars that are not visible to the naked eye and the only way to find objects (at least initially) is by using other stars to guide you there.
Calculating Magnification As implied in the previous section, you can change the power of your Celestron telescope just by changing the eyepiece (ocular). To determine the magnification for your telescope, simply divide the focal length of the telescope (1000mm) by the focal length of the eyepiece you are using. In equation format, the formula looks like this: Focal Length of Telescope (mm) Magnification = ————————————————— Focal Length of Eyepiece (mm) Let’s take an example to see how this formula works.
A S T R O N O M Y B A S I C S This section deals with observational astronomy in general. It includes information on the night sky, polar alignment, and using your telescope for astronomical observations. The Celestial Coordinate System In order to help find objects in system which is similar to our The celestial coordinate system an equator. For the most part, stars. the sky, astronomers use a celestial coordinate geographical coordinate system here on Earth.
Motion of the Stars Like the Sun, the stars also appear to move across the sky. This motion is caused by the Earth’s rotation. For observers in the northern hemisphere, all stars appear to move around the north celestial pole. For observers in the southern hemisphere, all stars appear to move around the south celestial pole. This means that over a 24hour period, any given star will scribe out a complete circle around its respective celestial pole.
Polar Alignment In order for the telescope to track the stars it must meet two criteria. First, you need a drive motor that will move at the same rate as the stars. For the G-8N there are two optional motor drives (#93518 and #93523) that can be fitted to it. For the C150-HD there are also two optional motor drives (#93517 and #93522). The second thing you need is to set the telescope’s axis of rotation so that it tracks in the right direction.
Finding the Pole Figure 4-4 The position of the Big Dipper changes throughout the year and throughout the night. For 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.
Latitude Scales The easiest way to polar align a telescope is with a latitude scale. Unlike other methods that require you to find the celestial pole by identifying certain stars near it, this method works off of a known constant to determine how high the polar axis should be pointed. The latitude range varies depending upon the telescope you own. The range for the CG-4 and CG-5 and is 40°.
Pointing at Polaris This method utilizes Polaris as a guidepost to the celestial pole. Since Polaris is less than a degree from the celestial pole, many amateurs simply point the polar axis of their telescope at Polaris. Although this is by no means a perfect alignment, it is close. To align using this method: Align the finderscope with the main optical tube as described in the "Aligning the Finder" section earlier in the manual.
Declination Drift This method of polar alignment allows you to get the most accurate alignment on the celestial pole and is required if you want to do long exposure deep-sky astrophotography through the telescope. The declination drift method requires that you monitor the drift of selected guide stars. The drift of each guide star tells you how far away the polar axis is pointing from the true celestial pole and in what direction.
Polar Alignment Finders There are two finders specifically designed for polar alignment that can be used with the CG-4 and CG-5 mounts. These finders can be purchased as optional accessories for the C150-HD and G-8N. The first finder, known as the 7x50 Polaris finder (#51614), is used as a regular finder. The second finder is the polar axis finderscope (#94221). Its sole purpose is polar alignment and can NOT be used to find objects in the telescope.
C E L E S T I A L O B S E R V I N G With your telescope set up, you are ready to use it for celestial observing. This section covers visual observing of both solar system and deep-sky objects. Observing the Moon In the night sky, the Moon is a prime target for your first look because it is extremely bright and easy to find. Often, it is a temptation 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.
Observing the Sun WARNING: 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 (always use the proper solar filter) 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.
Using the Setting Circles Once the setting circles are aligned you can use them to find any object with known coordinates. 1. Select an object to observe. Use a seasonal star chart or planisphere to make sure the object you chose is above the horizon. As you become more familiar with the night sky, this will no longer be necessary. 2. Look up the coordinates in an atlas or reference book. 3. Move the telescope in declination until the indicator is pointing at the correct declination coordinate. 4.
Star Hopping You can use your setting circles to find these objects (as described earlier in this manual) or try star hopping. Star hopping is done by using bright stars to guide you to an object. Here are directions for two popular objects. The Andromeda Galaxy, M31, is an easy first target. To find M31: 1. Locate the constellation of Pegasus, a large square visible in the fall and winter months. 2. Start at the star in the northeast corner. The star is Alpha (α) Andromedae. 3.
Star hopping may take some getting used to since you can see more stars through the finder than you can see with the naked eye. And, some objects are not visible in the finder. One such object is M57, the famed Ring Nebula. Here’s how to find it: 1. Find the constellation of Lyra, a small parallelogram visible in the summer and fall months. Lyra is easy to pick out because it contains the bright star Vega. 2.
Viewing 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 affect they have on observing will help you get the most out of your telescope. Transparency Transparency is the clarity of the atmosphere and is affected by clouds, moisture, and other airborne particles.
temperature, don’t touch the telescope tube with your hands. When pointing the telescope, hold the telescope by the star diagonal. If observing with others, make sure no one stands in front of or directly below the telescope tube. The images produced by Type 2 seeing conditions don’t move as quickly as those produced by Type 1 conditions, but the images are quite blurry. Fine detail is lost and the contrast is low for extended objects. Stars are spread out and not sharp.
C E L E S T I A L P H O T O G R A P H Y After looking at the night sky for awhile you may want to try photographing it. Several forms of celestial photography are possible with your Celestron telescope. The most common forms of celestial photography, in order of difficulty are: short exposure prime focus, piggyback, eyepiece projection, and long exposure deep sky. Each of these is discussed in moderate detail with enough information to get you started.
Short Exposure Prime Focus Short exposure prime focus photography is the best way to begin recording celestial objects. It is done with the camera attached to the telescope without an eyepiece or camera lens in place. To attach your camera, you need the T-adapter and a T-Ring for your specific camera (i.e., Minolta, Nikon, Pentax, etc.). The C150-HD and G-8N focuser have built-in T-adapter and are ready to accept a 35mm camera body. The TRing replaces the 35mm SLR camera’s normal lens.
The exposure times listed here should be used as a starting point. Always make exposures that are longer and shorter than the recommended time. Also, try bracketing your exposures, taking a few photos at each shutter speed. This will ensure that you will get a good photo. If using black and white film, try a yellow filter to reduce the light intensity and to increase contrast. Keep accurate records of your exposures.
9. Close the camera’s shutter. As for lenses, use good ones that produce sharp images near the edge of the field. The lenses should have a resolving power of at least 40 lines per millimeter. A good focal length range is 50 to 500mm for lenses designed for 35mm cameras. The exposure time depends on the film being used. However, five minutes is usually a good starting point. With slower films, like 100 ISO, you can expose as long as 45 minutes.
T E L E S C O P E M A I N T E N A N C E After you have set up your telescope and started using it, there are a few things to remember for future reference. Care and Cleaning of the Optics To minimize the need to clean your telescope, replace all lens covers once you have finished using it. Since the front of the telescope tube is open ALWAYS replace the front cover when the telescope is not in use.
Prior to collimating the primary mirror holder, locate the three (3) screws on the end plate at the end of the tube. Unthread the three screws and remove the plate from the end of the tube. Under the end plate there are three (3) sets of two (2) screws. The shorter Allen screws push the mirror holder which is held by the longer outer screws. In order to make an adjustment, the outer screw is loosened while the shorter screw is turned in or out. Then, the outer screw is tightened.
O P T I O N A L A C C E S S O R I E S The following is a partial list of optional accessories available for your Celestron C150-HD and G-8N. 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 C150-HD and G-8N.
• 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! They are available in the following focal lengths: 2.5mm, 4mm, 5mm, 6mm, 9mm, 10mm, 12mm, 15mm, 20mm and 25mm. Celestron also offers the LV Zoom eyepiece (#3777) with a focal length of 8mm to 24mm.
Single Axis Motor Drive System - #93518 By adding the MDCG-5 Drive System to your mount, you add the capacity to automatically track objects in the sky, a convenience you’ll be sure to enjoy during long viewing or astrophotography sessions, when manual tracking can become tiring. Furthermore, the Drive System will enhance high-power visual observing. It attaches to the R.A.
THE MESSIER CATALOG The Messier Catalog, compiled by Charles Messier, was the first extensive listing of star clusters and nebulae. Messier’s primary observational purpose was to discover comets. He compiled this list so that others searching for comets would not be confused by these objects. His list still remains popular today because all of these objects are easily visible in amateur telescopes. M# NGC# Const. R.A.
M# NGC# Const. R.A. HMS DEC °‘ Mag Type M36 M37 M38 M39 M40 NGC 1960 NGC 2099 NGC 1912 NGC 7092 Aur Aur Aur Cyg UMa 5 5 5 21 12 36.3 52.0 28.7 32.3 22.2 34 32 35 48 58 08 33 50 26 05 6.0 5.6 6.4 4.6 8.0 Op. Cl. Op. Cl. Op. Cl. Op. Cl. dbl M41 M42 M43 M44 M45 NGC 2287 NGC 1976 NGC 1982 NGC 2632 CMa Ori Ori Cnc Tau 6 5 5 8 3 47.0 35.3 35.5 40.0 47.5 -20 -5 -5 19 24 44 27 16 59 07 4.5 4.0 9.0 3.1 1.2 Op. Cl. D. Neb. D. Neb. Op. Cl. Op. Cl.
M# NGC# Const. R.A. HMS DEC °‘ Mag Type Proper Name M81 M82 M83 M84 M85 NGC 3031 NGC 3034 NGC 5236 NGC 4374 NGC 4382 UMa UMa Hya Vir Com 9 9 13 12 12 55.8 56.2 37.7 25.1 25.4 69 69 -29 12 18 04 41 52 53 11 6.8 8.4 7.6 9.3 9.2 Sp. Gx. Ir. Gx. Sp. Gx. El. Gx. El. Gx. Bodes Nebula M86 M87 M88 M89 M90 NGC 4406 NGC 4486 NGC 4501 NGC 4552 NGC 4569 Vir Vir Com Vir Vir 12 12 12 12 12 26.2 30.8 32.0 35.7 36.8 12 12 14 12 13 57 24 25 33 10 9.2 8.6 9.5 9.8 9.5 El. Gx. El. Gx. Sp. Gx. El. Gx.
LIST OF BRIGHT STARS The following is a list of bright stars that can be used to align the R.A. setting circle. All coordinates are in epoch 2000.0. Star Name Constellation Epoch 2000.0 DEC R.A. HMS °‘“ Magnitude Sirius Canopus Arcturus Rigel Kent. Vega CMa Car Boo Cen Lyr 06 06 14 14 18 45 09 23 57 15 40 39 37 36 56 -16 -52 +19 -60 +38 42 58 41 44 10 57 50 02 47 01 -1.47 -0.72 -0.72 +0.01 +0.
FOR FURTHER READING The following is a list of astronomy books that will further enhance your understanding of the night sky. The books are broken down by classification for easy reference. Astronomy Texts Astronomy Now .................................................................................................... Pasachoff & Kutner Cambridge Atlas Of Astronomy .......................................................................... Audouze & Israel McGraw-Hill Encyclopedia Of Astronomy ............
CELESTRON ONE YEAR WARRANTY A. Celestron warrants this telescope to be free from defects in materials and workmanship for one year. Celestron will repair or replace such product or part thereof which, upon inspection by Celestron, is found to be defective in materials or workmanship. As a condition to the obligation of Celestron to repair or replace such product, the product must be returned to Celestron together with proof-of-purchase satisfactory to Celestron. B.
2835 Columbia Street Torrance, CA 90503 Tel. (310) 328-9560 Fax (310) 212-5835 www.celestron.com Copyright 2002 Celestron All rights reserved. (Products or instructions may change without notice or obligation.) Item # 31058-INST 08-02 Price $10.
