User manual CELESTRON CI-700 - Instruction Manual

CELESTRON CI-700 / CM-1100 / CM-1400 INSTRUCTION MANUAL Models #91525 / #11055 / #11065 T h e C e l e s t r o n C M- 1 1 00/1400 Copyright © 1998 Celestron International 2835 Columbia Street Torrance, CA 90503 (310) 328-9560 No part of this manual may be reproduced in any form or by any means, electronic or mechanical, including photocopying, recording, or by any information storage and retrieval system, without written permission from Celestron International. Celestron International provides this manual "as is" without warranty of any kind, either expressed or implied, including but not limited to the implied warranties of merchantability and fitness for a particular purpose. Celestron may make modifications to this manual and/or the products described herein at any time without notice or obligation. ii · Table of Contents TABLE OF CONTENTS 1 2 2 3 v INTRODUCTION .................................................................................................................................. How to Use this Manual ..................................................................................................................... A Word of Caution ............................................................................................................................. The Schmidt-Cassegrain Optical System .......................................................................................... v ASSEMBLING YOUR CELESTRON CM-1100 ...................................................................................... 4 Unpacking Your Celestron CM-1100 .................................................................................................. 4 Setting Up the Tripod ......................................................................................................................... 6 Attaching the Center Leg Brace ........................................................................................................ 7 Attaching the Central Column ............................................................................................................ 7 Attaching the Equatorial Mount .......................................................................................................... 8 Installing the Counterweight Bar ........................................................................................................ 9 Installing the Counterweight ............................................................................................................... 9 Attaching the Celestron CM-1100 to the Mount ................................................................................ 10 Attaching the Visual Back ................................................................................................................11 Installing the Star Diagonal ...............................................................................................................11 Installing the Eyepiece .....................................................................................................................12 Installing the Finder .......................................................................................................................... 13 Installing the Polar Axis Finder .........................................................................................................14 Moving the Telescope in R.A. and DEC ............................................................................................ 15 Using the Slow Motion Controls ........................................................................................................ 15 Adjusting the Mount .........................................................................................................................16 Balancing the Mount in R.A. .............................................................................................................17 Balancing the Mount in DEC .............................................................................................................18 Transporting Your Celestron CM-1100 ..............................................................................................19 Storing Your Celestron CM-1100 ......................................................................................................19 Technical Specifications ...................................................................................................................20 v TELESCOPE BASICS .........................................................................................................................22 Image Orientation ............................................................................................................................. 22 Focusing ..........................................................................................................................................23 General Photography Hints ...............................................................................................................24 Aligning the Finder ............................................................................................................................24 Your First Look .................................................................................................................................25 Daytime Observing .....................................................................................................................25 Nighttime Observing ...................................................................................................................26 Calculating Magnification ..................................................................................................................27 Determining Field of View ................................................................................................................. 27 v ASTRONOMY BASICS ....................................................................................................................... 28 The Celestial Coordinate System ......................................................................................................28 Motion of the Stars ...........................................................................................................................29 Polar Alignment ................................................................................................................................ 30 Finding the Pole ...............................................................................................................................31 Latitude Scales .......................................................................................................................... 32 Pointing at Polaris ......................................................................................................................33 The Polar Axis Finder ................................................................................................................. 34 Declination Drift .......................................................................................................................... 35 Aligning the Setting Circles .............................................................................................................36 Table of Contents · iii v USING THE DRIVE ............................................................................................................................. 37 Powering Up the Drive ......................................................................................................................37 Guide Speed ....................................................................................................................................38 Tracking Rate Selection.................................................................................................................... 38 BC -Backlash Correction ..................................................................................................................39 Periodic Error Correction ..................................................................................................................39 HC/CCD ...........................................................................................................................................40 12 V DC ...........................................................................................................................................40 Northern/Southern Hemisphere Operation ......................................................................................... 41 Using the Hand Controller ................................................................................................................. 41 R.A./DEC Reverse ............................................................................................................................42 Autoguiding ...................................................................................................................................... 42 v CELESTIAL OBSERVING ...................................................................................................................43 Observing the Moon .......................................................................................................................... 43 Observing the Planets ......................................................................................................................43 Observing the Sun ............................................................................................................................44 Observing Deep-Sky Objects ............................................................................................................45 Using the Setting Circles ........................................................................................................... 45 Star Hopping ..............................................................................................................................46 Viewing Conditions ...........................................................................................................................48 Transparency ............................................................................................................................. 48 Sky Illumination .........................................................................................................................48 Seeing .......................................................................................................................................48 v CELESTIAL PHOTOGRAPHY .............................................................................................................50 Short Exposure Prime Focus ........................................................................................................... 51 Piggyback ........................................................................................................................................53 Eyepiece Projection .........................................................................................................................55 Long Exposure Prime Focus ............................................................................................................57 CCD Imaging ....................................................................................................................................59 Description of F-Numbers ............................................................................................................60 Fastar Configuration ...................................................................................................................60 Imaging at f/2.1 .......................................................................................................................... 61 Imaging at f/7 ............................................................................................................................. 61 Imaging at f/11 ...........................................................................................................................61 Imaging at f/22 ...........................................................................................................................62 v TELESCOPE MAINTENANCE .............................................................................................................63 Care and Cleaning of the Optics .......................................................................................................63 Collimation .......................................................................................................................................63 v OPTIONAL ACCESSORIES ................................................................................................................66 v THE MESSIER CATALOG ..................................................................................................................70 v LIST OF BRIGHT STARS ...................................................................................................................73 v FOR FURTHER READING ...................................................................................................................74 iv · Table of Contents INTRODUCTION Welcome to the Celestron world of amateur astronomy! For more than a quarter of a century, Celestron has provided amateur astronomers with the tools needed to explore the universe. The Celestron CM-1100 and CM-1400 continues in this proud tradition combining large aperture optics with ease of use and portability. With a mirror diameter of 11 inches, your Celestron CM1100 has a light gathering power of 1,593 times that of the unaided human eye, and the CM-1400 has a light gathering power of 2,581 times that of the unaided human eye. Yet despite their large apertures, the Celestron CM-1100 and CM1400 optical systems are extremely compact and portable because they utilize the Schmidt-Cassegrain design. This means you can take your Celestron CM1100 or CM-1400 to the mountains or desert or wherever you observe. The Celestron CM-1100 and CM-1400 are made of the highest quality materials to ensure stability and durability. All this adds up to telescopes that will give you a lifetime of pleasure with a minimal amount of maintenance. And, your Celestron CM-1100 and CM-1400 are versatile -- they grow as your interest in astronomy grows. Your Celestron CM-1100 and CM-1400, are not limited to astronomical viewing alone. They can also be used for terrestrial viewing to study the world around you. All you need to do is take the time to familiarize yourself with your Celestron telescope and its operation. NOTE The CM-1100 and CM-1400 share the same mount and are basically the same with the exception of the larger aperture of the 14". So, this manual will basically discuss the CM-1100 but will discuss the CM-1400 when there are differences. Users of the CI-700 mount by itself will find complete assembly and operation instructions in the "AssemblingYour CM-1100" and "Using the Drive" sections of this manual. Introduction · 1 How to Use This Manual This manual is designed to instruct you in the proper use of your Celestron CM-1100 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 CM1100 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. Topics include focusing, aligning the finder, and taking your first look. The third section deals with the basics of astronomy which includes the celestial coordinate system, the motion of the stars, and polar alignment. The fourth section deals with celestial observing covering visual observations of the planets and deepsky objects. Using both the setting circles and star hopping are discussed. The fifth section covers celestial photography working from the easiest to the most difficult. The last major section is on telescope maintenance, specifically on cleaning and collimation. Keeping your CM-1100 in proper collimation is the single most important thing you can do to ensure it performs well. In addition to the major sections mentioned previously, there is a list of optional accessories for your Celestron CM-1100 that include a brief description of its purpose. This is the section to consult when you've mastered the basics and are ready for new, more challenging observations. The final part of this manual contains a list of objects that can be observed through your Celestron CM-1100 telescope. Included are the coordinates for each object, its brightness, and a code which indicates what type of an object it is. In addition, there is a list of bright stars used for aligning the setting circles. Read the assembly instructions through completely before you attempt to set up your Celestron CM-1100 telescope. Then, once you've set up your Celestron CM-1100, read the section on "Telescope Basics" before you take it outside and use it. This will ensure that you are familiar with your telescope before you try to use it under a dark sky. Since it will take a few observing sessions to familiarize yourself with your Celestron CM-1100, you should keep this manual handy until you have fully mastered your telescope's operation. After that, save the manual for future reference. A Word of Caution Your Celestron CM-1100 is designed to give you hours of fun and rewarding observations. There are, however, a few things to consider before using your telescope that will ensure your safety and protect your equipment. NEVER LOOK DIRECTLY AT THE SUN WITH THE NAKED EYE OR WITH A TELESCOPE. 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/OR 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 CHIL- WARNING ! 2 · Introduction DREN ARE PRESENT OR ADULTS WHO MAY NOT BE FAMILIAR WITH THE CORRECT OPERATING PROCEDURES OF YOUR TELESCOPE. NEVER POINT YOUR TELESCOPE AT THE SUN UNLESS YOU HAVE THE PROPER SOLAR FILTER. WHEN USING YOUR TELESCOPE WITH THE CORRECT SOLAR FILTER, ALWAYS COVER THE FINDER. ALTHOUGH SMALL IN APERTURE, THIS INSTRUMENT HAS ENOUGH LIGHT GATHERING POWER TO CAUSE PERMANENT AND IRREVERSIBLE EYE DAMAGE. IN ADDITION, THE IMAGE PROJECTED BY THE FINDER IS HOT ENOUGH TO BURN SKIN OR CLOTHING. The Schmidt-Cassegrain A telescope is nothing more than an instrument that collects and focuses light. The nature of the optical design determines how the light is focused. Some Optical System telescopes, known as refractors, use lenses while others, known as reflectors, use mirrors. The Schmidt-Cassegrain optical (or Schmidt-Cass for short) system uses a combination of mirrors and lenses and is referred to as a compound or catadioptric telescope. This unique design offers large diameter optics while maintaining very short tube lengths, making them extremely portable. This makes them extremely popular among amateur astronomers. The Schmidt-Cassegrain system consists of a zero power corrector plate, a spherical primary mirror, and a secondary mirror. Once light rays enter the optical system, they travel the length of the optical tube three times. Inside the optical tube you will notice a black tube (not illustrated) that extends out from the center hole in the primary mirror. This is the primary baffle tube which prevents stray light from passing through to the eyepiece or camera without striking the primary or secondary mirrors. Figure 1-1 This cross-sectional diagram shows the light path of the Schmidt-Cassegrain optical system. Note that the light rays travel the length of the telescope tube three times, making this a compact optical design. Note that the curve of the corrector plate is greatly exaggerated. Introduction · 3 ASSEMBLING YOUR CM-1100 This section covers the assembly instructions for your Celestron CM-1100 telescope. The Celestron CM-1100 should be set up indoors the first time so that it is easy to identify the various parts and familiarize yourself with the correct assembly procedure before attempting it outdoors. The Celestron CM-1100 is a standard 11" Schmidt-Cassegrain telescope on a heavy-duty German equatorial mount. The Celestron CM-1100 comes standard with Starbright TM enhanced multilayer aluminum coatings on the primary and secondary mirrors for increased reflectivity. Also, the corrector plate is fully coated to allow maximum light transmission. The Celestron CM-1100 is shipped in six boxes. One contains the telescope and is accompanied by a box that contains most of the standard accessories, which are: · 26mm Plössl Ocular 1-1/4" · Visual Back 1-1/4" (2" Visual Back on the CM-1400) · Star Diagonal 1-1/4" (2" Mirror Diagonal for the CM-1400) · 9x50mm Finderscope with Bracket · Car Battery Adapter · Lens Cap In separate boxes are the following: · Optical Tube Assembly · Equatorial Mount and Counterweight Bar · Tripod · Central Column, Electronics Module, Polar Axis Finder and Hand Control · One 23 Pound Counterweight (The CM-1400 come with two 25 lb. counterweights) · Accessories for Optical Tube Included is all the hardware needed to assemble the telescope. Use the diagram on the following page (see Figure 2-1) to familiarize yourself with the various parts of your Celestron CM-1100 telescope. Unpacking Your Celestron CM-1100 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 CM1100) you must start with the tripod and work up from there. These instructions are laid out in the order each task must be performed. 4 · Assembling Your CM-1100 16 1 2 15 14 13 12 3 4 5 11 10 6 7 9 8 CM-1100 Figure 2-1 1. 2. 3. 4. 5. 6. 7. 8. Optical Tube Finderscope Star Diagonal Eyepiece Polar Axis Finderscope Drive Control Electronics Hand Control Tripod 9. Center Leg Brace 10. Counterweight 11. Counterweight Bar 12. R.A. Clutch Knob 13. DEC Clutch Knob 14. Mounting Platform Clamp Knob 15. Dovetail Slidebar 16. Objective Lens Cover Assembling Your CM-1100 · 5 Setting Up the Tripod The tripod legs attach to a central column which together form the tripod to which the equatorial mount attaches. The tripod comes with two leg support brackets; a collapsible one that is already attached to the lower legs and a removable one that must be attached. To set up the tripod: 1. Stand the tripod vertically on a level surface, with the feet facing down (See Figure 2-2). 2. Grab the lower portion of two of the tripod legs and lift them slightly off the ground so that the tripod is resting on the third leg. 3. Extend the tripod legs by pulling the tripod legs apart until the collapsible leg bracket is fully extended. (See Figure 2-3) Before the tripod is ready to support the equatorial head and optical tube the center leg support brace must first be installed. Figure 2-2 Figure 2-3 6 · Assembling Your CM-1100 Attaching the Center Leg Brace For maximum rigidity, the CI 700 tripod has a center leg brace that installs on to the threaded rod below the tripod head. This brace fits snugly against the tripod legs, increasing stability while reducing vibration and flexure. To attach the center leg brace: 1 Unscrew the tension knob from the threaded rod beneath the tripod head. Place the center leg brace onto the threaded rod so that the cup on the end of each bracket contours to the curve of the tripod legs. Rotate the tension knob back on the threaded rod until the brace is very snug against each tripod leg. Central Column Electronics Console 2 3 Center Leg Brace Figure 2-4 Attaching the Central Column Before the equatorial mount head can be installed, the central column with the electronics module must be attached to the tripod. To attach the central column: 1 Position the central column so that the electronics module is right side up (see Figure 2-4). Place the lower end of the central column over the tripod head. Rotate the column until the three holes line up with the threaded holes on the side of the tripod head. The electronics console should be positioned directly between two of the tripod leg hinges to provide easy access to it even when the counterweight bar and counterweight(s) are attached. Insert the three 3/8-16 button head cap screws provided through the holes in the central column and into the tripod head. Tighten the screws to hold the column securely in place. 2 3 4 5 Assembling Your CM-1100 · 7 Attaching the Equatorial Mount After the tripod is set up, you are ready to attach the equatorial mount. The equatorial mount is the platform to which the telescope attaches and allows you to move the telescope in right acsension and declination. The mount is also adjustable so you can orient the axis of rotation so that it is parallel with the Earth's axis of rotation (see the section on "Polar Alignment"). To attach the equatorial mount to the tripod: 1. Insert the base of the equatorial mount into the top of the central column. 2. Rotate the equatorial mount on the central column until the holes in the mount line up with those in the central column and the dec opening (where the counterweight shaft will go) is positioned directly over one of the tripod legs. 3. Insert the three remaining 3/8-16 cap screws and washers provided through the holes in the central pier and into the equatorial mount (see Figure 2-5). 4. Tighten the screws to hold the equatorial mount in place. Counterweight Shaft Opening Equatorial Mount Central Column Figure 2-5 8 · Assembling Your CM-1100 Installing the Counterweight Bar To properly balance the telescope, the mount comes with a counterweight bar and one counterweight (the CM-1400 comes with two counterweights). The counterweight bar is located in the same box as the Equatorial Mount Head -- in a cutout along the bottom of the shipping box. To install the counterweight bar: 1. Locate the opening in the equatorial mount on the DEC axis (see figure 26). It is opposite the telescope mounting platform. 2. Thread the counterweight bar into the opening until tight. HINT Once the bar is securely in place you are ready to attach the counterweight. Since the fully assembled telescope is quite heavy, position the mount so that the tripod leg with the counterweight bar over it is pointing towards north before the tube assembly and counterweights are attached. This will make the polar alignment procedure much easier. Counterweight Bar Counterweight Bar Safety Screw Figure 2-5 Installing the Counterweight Figure 2-6 The Celestron CM-1100 comes standard with one 23 pound counterweight. The CM-1400 comes with two 25 pound counterweights. To install the counterweight(s): 1. Orient the mount so that the counterweight bar points toward the ground (see figure 2-7). Counterweight Bar 2. Remove the counterweight safety thumbscrew and washer on the end of the counterweight bar (i.e., opposite the end that attaches to the mount). 3. Loosen the set screw on the side of the counterweight. 4. Slide the counterweight onto the shaft. 5. Tighten the locking screw on the side of the weight to hold the counterweight in place. Counterweight 6. Replace the counterweight safety thumbscrew and washer. Figure 2-7 Assembling Your CM-1100 · 9 Attaching the Optical Tube to the Mount The telescope attaches to the mount via a dovetail slide bar which is mounted along the bottom of the telescope. Before you attach the optical tube, make sure that the declination and right ascension clutch knobs are tight. This will ensure that the mount does not move suddenly while attaching the telescope. To mount the telescope tube: 1 Loosen the knobs on the side of the telescope mounting platform. This allows you to slide the dovetail bar on the telescope onto the mount. 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 almost flush with the back of the mounting platform. Tighten the locking knobs on the side of the mounting platform to hold the telescope in place. Slide the dovetail slide bar safety clamp down the front end of the slide bar until it touches the mounting platform. This clamp is designed to keep the telescope from sliding off the mount in case the knobs on the side of the platform comes loose. It is best to wait until the telescope is balanced in R.A. and DEC before attaching the safety clamp (see "Balancing the Mount in DEC" later in this section). 2 3 4 Optical Tube Dovetail Slide Bar Mounting Platform Mounting Platform Locking Knobs Figure 2-8 10 · Assembling Your CM-1100 Attaching the Visual Back The visual back is the accessory that allows you to attach all visual accessories to the telescope. To attach the visual back: 1. Remove the plastic cover on the rear cell. 2. Place the knurled slip ring on the visual back over the threads on the rear cell. 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 separates from the rear cell. Installing the Star Diagonal 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: NOTE: The CM-1400 uses a 2" mirror diagonal. 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. Figure 2-9 Assembling Your CM-1100 · 11 Installing the Eyepiece The eyepiece, or ocular, is an optical element that magnifies the image focused by the telescope. The ocular(s) fit into either the visual back directly, the star diagonal, or the Erect Image Diagonal (purchased separately). To install an ocular: 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. 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 ocular (purchased separately). NOTE: The 2" mirror diagonal has a 1 1/4" eyepiece adapter to use 1 1/4" eyepieces. You may remove the adapter to use 2" eyepieces. 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." Figure 2-10 12 · Assembling Your CM-1100 Installing the Finder The CM-1100 telescope come with a 9x50 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. Start by removing the finder and hardware from the plastic wrapper. Included are the following: · 9x50mm Finder · Finder Bracket · Rubber O-ring · Three Nylon Tipped Thumbscrews (10-24x1/2") · Two Allen Head Screws (8-32x1/2") To install the finder: 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 Figure 2-1). Start threading the screws in by hand and tighten fully with an Allen wrench. 2. Partially thread-in the three nylon-tipped 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 tipped 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. 8. Hand tighten the three nylon tipped thumbscrews until snug. Assembling Your CM-1100 · 13 Installing the Polar Finder To aid in polar aligning the mount, your telescope comes standard with a Polar Housing Finder. It installs directly on top of the polar housing of the mount. To install the Polar Finder: 1. Locate the Polar Finder assembly. The Polar Finder assembly consists of the polar finder, mounting bracket and knurled mounting screw (see Figure 2.11). 2. Place the Polar Finder Assembly on top of the polar axis housing so that the mounting stop on the metal bracket sits flush against the rear of the polar housing. 3. Secure the Polar Finder Assembly to the mount by threading the Knurled Mounting Screw into the threaded hole on top of the Polar Housing. The Polar Axis Finder is now installed and ready to use. To learn how to polar align the mount using the Polar Axis Finder, refer to the Astronomy Basics section of the manual. Nylon Tension Screw Finderscope Bracket Assembly Polar Finderscope Knurled Mounting Screw Mounting Stop Polar Axis Housing Figure 2-11 14 · Assembling Your CM-1100 Moving the Telescope in R.A. and DEC Once set up, you need to point your telescope 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 two knobs to clutch down each axis of the telescope. To loosen the clutches on the telescope, rotate the clutch knobs (see figure below) counterclockwise. Once your have found your desired object in the finderscope, rotate the clutch knobs on each axis clockwise to lock the telescope in place. DEC Clutch Knobs DEC Slow Motion Control R.A. Slow Motion Control Using the Slow Motion Controls R.A. Clutch Knobs Figure 2-12 The CI 700 mount is equipped with slow motion controls on both the R.A. and Declination axis. Each slow motion control has a clutch mechanism that allows you to override the tracking motor and adjust the amount of tension when turning the knob. To adjust the clutch mechanism, hold the slow motion knob with one hand, and rotate the clutch wheel with your other hand. Rotate the clutch wheel clockwise (downward) to increase the tension on the slow motion control and counterclockwise (upward) to decrease the tension. Slow Motion Knob Clutch Wheel Figure 2-13 Assembling Your CM-1100 · 15 Adjusting the Mount In order for the clock 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 "Polar Alignment." To adjust the mount in altitude: 1. Locate the altitude adjustment bolt just above the tripod column (see figure 2-14). 2. Using the 7/32" Allen wrench provided, turn the altitude adjustment bolt until the mount is at the right elevation. The total altitude range is from 13° to 65°. With the 23 lb counterweight attached to the counterweight shaft, the equatorial head can go as low as 20° without hitting the tripod leg. To adjust the mount in azimuth: 1. Locate the azimuth adjustment bolt on the flat portion of the tripod column. 2. Loosen the two azimuth lock knobs located on the top of the tripod column. 3. Turn the azimuth adjustment bolt with the 7/32" Allen wrench until the polar axis is pointing in the right direction. 4. Tighten the azimuth lock knobs to hold the mount in place. The mount can be moved ± 7° in azimuth using these bolts. 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. Once the appropriate adjustments have been made and you are aligned on the celestial pole, turn the clock drive on and the telescope will track. Azimuth Lock Screws Altitude Adjustment Bolt Azimuth Adjustment Bolt Bubble Level Figure 2-14 16 · Assembling Your CM-1100 Balancing the Mount in R.A. 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: 1. Verify that the telescope securing knobs on the telescope mounting platform are tight. 2. Loosen the R.A. clutch knobs 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 set 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 2-15 With the standard accessories attached, the counterweight should be at the far end of the counterweight bar. Assembling Your CM-1100 · 17 Balancing the Mount in DEC 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 clutch knob is loose. To balance the telescope in DEC: 1. Loosen the R.A. clutch knobs 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. clutch knobs to hold the telescope in place. 3. Loosen the DEC clutch knobs and rotate the telescope until the tube is parallel to the ground. 4. Release the tube -- GRADUALLY -- to see which way it rotates around the declination axis. DO NOT LET 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. 6. Tighten the knobs on the telescope mounting platform to hold the telescope in place. Once the telescope is balanced in declination, slide the dovetail bar safety clamp down the front of the telescope's slide bar until it touches the mounting platform and tighten the locking bolt (see Figure 2-16). This not only acts as a safety in case the mounting platform knobs are loosened, but will also allow you to put the tube on the mount in the exact same position each time for perfect balance. 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. Dovetail Slide Bar Safety Clamp Dovetail Slide Bar Figure 2-16 With the standard accessories attached, the end of the dovetail bar should be almost flush with the end of the telescope mounting platform. . 18 · Assembling Your CM-1100 Transporting Your Celestron CM-1100 Because of the Celestron CM-1100's size and weight, you should ALWAYS remove the telescope from the mount when moving the telescope. To do so: 1. Take the telescope off of the mount and return it to its shipping box. 2. Remove the counterweight from the counterweight bar. 3. Remove the counterweight bar from the mount. 4. Remove the finderscope from the optical tube. 5. Take the equatorial mount off of the central column. 6. Remove the center leg brace from the tripod. 7. Collapse the tripod legs inward, towards each other. The telescope is now broken down into enough pieces to be easily transported. Storing Your Celestron CM-1100 When not in use, your Celestron CM-1100 can be left fully assembled and set up. However, all lens and eyepiece covers should be put back in place. This will reduce the amount of dust build-up on all optical surfaces and reduce the number of times you need to clean the instrument. You may want to return everything to its original shipping container and store it there. If this is the case, all optical surfaces should still be covered to prevent dust accumulation. If you are in the field, and plan on being there for a few days, use a plastic tarp to cover the telescope and mount. Assembling Your CM-1100 · 19 Technical Specifications Below is pertinent technical information on your Celestron CM-1100 telescope that you may find useful. OPTICAL TUBE: Optical System: Aperture: Focal Length: F/ratio: Highest Useful Power Magnification: Lowest Useful Power Magnification: Resolution (arc seconds): Photographic Resolution: Light Gathering Power: Limiting Visual Magnitude: Near Focus with eyepiece: with camera: Optical Tube Length: Weight Optical Tube: CM-1100 Schmidt-Cassegrain 11" (279mm) 2800mm (110.2") f/10 660x 42x 0.41 200 lines/mm 1593x 14.7 60' 60' 25" 27.5 lbs. CM-1400 Schmidt-Cassegrain 14" (356mm) 3910mm (153.9") f/11 840x 50x 0.33 182 lines/mm 2581x 15.3 175' 225' 32" 45 lbs. DEC AXIS: · All machined stainless steel and aluminum · 5.625 diameter precision bronze worm gear, 180 tooth. AGMA quality 10. · .4375 diameter precision 303 stainless steel worm. AGMA quality 10. Dual bearing supported. · One inch diameter solid shaft, centerless ground · Two 2" preloaded Tapper Roller Bearings, pre-loading the shaft. · Bearing preload is independent of clutch tension. · Slip Clutch-Variable friction two knob adjustment · 5.25" laser engraved setting circle, 1 degree increments. · 182 oz/in Stepper Motor - .50 arc second steps · Removable stainless steel counterweight shaft · Dovetail saddle plate ­ allowing for interchanging of any tube assembly · Instrument Weight of 60 Lbs POLAR AXIS: · All machined stainless steel and aluminum · 5.625 diameter precision bronze worm gear, 180 tooth. AGMA quality 10. · .4375 diameter precision 303 stainless steel worm. AGMA quality 10. Dual bearing supported. · One inch diameter solid shaft, centerless ground · Two 2" preloaded Tapper Roller Bearings, pre-loading the shaft. · Bearing preload is independent of clutch tension. · Slip Clutch-Variable friction two knob adjustment · 5.25" driven laser engraved setting circle, 5 minute increments (Northern Hemisphere only) · 182 oz/in Stepper Motor - .50 arc second steps · Latitude adjustment 20 to 65 degrees with counterweights. Total travel is 13 to 65 degrees. · Azimuth adjustment, bi-directional +/- 7 degrees 20 · Assembling Your CM-1100 TRIPOD: · All machined aluminum · Semi-pier Tripod Design · Fixed hieght Tripod with dual leg support · Tripod legs are 48.5" long · Tripod hieght is 49" high (fully extended with column attached) · Tripod weight approximately 20 pounds · Weight of equatorial head 31 pounds CONTROL SYSTEM: · Diamond push button pattern · Hand Control: Reversible R.A. and DEC, Autoguider ready (use an autoguider and the hand control at the same time) · Two photo guide rates: .3x, and .5x sidereal · Three slew rates: 8x, 16x, and 20x (double button hand control, see chapter on Hand Control use) · Quartz tracking rates; Sidereal, Solar, Lunar, King · Periodic Error Correction (PEC) · Accepts Auto-Guider Systems · Northern and Southern Hemisphere operation · Backlash compensation for declination axis. · 12 Volt DC - 500 MA power use Note: All specifications are stated for the Celestron CM telescopes using the standard accessories. Also, these specifications are approximate and subject to change without notice. Assembling Your CM-1100 · 21 TELESCOPE BASICS Once your telescope is fully assembled, you are ready for your first look. This section deals with some of the basics of telescope operation. Image Orientation The image orientation changes depending on how the eyepiece is inserted into the telescope. When using the star diagonal, the image is right-side-up, but reversed from left-to-right (i.e., reverted). If inserting the eyepiece directly into the visual back (i.e., without the star diagonal), the image is upside-down and reversed from left-to-right (i.e., inverted). This is normal for the SchmidtCassegrain design and applies to the telescope's finder as well. Figure 3-1 These simplified drawings of the planet Jupiter illustrate the different image orientations obtained when using various viewing configurations. 22 · Telescope Basics Focusing The Celestron CM-1100 focusing mechanism controls the primary mirror which is mounted on a ring which slides back and forth on the primary baffle tube. The focusing knob, which moves the primary mirror, is on the rear cell of the telescope just right of the star diagonal and eyepiece. Turn the focusing knob until the image is sharp. If the knob will not turn, it has reached the end of its travel on the focusing mechanism. Turn the knob in the opposite direction until the image is sharp. Once an image is in focus, turn the knob clockwise to focus on a closer object and counterclockwise for a more distant object. A single turn of the focusing knob moves the primary mirror only slightly. Therefore, it will take many turns (about 40) to go from close focus (approximately 65 feet) to infinity. For critical focusing, both visually and photographically, turn the focus knob counterclockwise until the image is sharp. Turning the focusing knob in this direction pushes the primary mirror forward, or against the pull of gravity, which minimizes any mirror shift. When working with any optical instrument, there are a few things to remember to ensure you get the best possible image. · Never look through window glass. Glass found in household windows is optically imperfect, and as a result, may vary in thickness from one part of a window to the next. This inconsistency can and will affect the ability to focus your telescope. In most cases you will not be able to achieve a truly sharp image. In some cases, you may actually see a double image. · Never look across or over objects that are producing heat waves. This includes asphalt parking lots on hot summer days or building rooftops. · Hazy skies, fog, and mist can also make it difficult to focus when viewing terrestrially. The amount of detail seen under these conditions is greatly reduced. Also, when photographing under these conditions, the processed film may come out a little grainier than normal with lower contrast. · When using your telescope as a telephoto lens, the split screen or microprism focuser of the 35mm SLR camera may "black out." This is common with all long focal length lenses. If this happens, use the ground glass portion of your focusing screen. To achieve a very sharp focus you may consider using a focusing magnifier. (These are readily available from your local camera store.) · If you wear corrective lenses (specifically glasses), you may want to remove them when observing with an eyepiece attached to the telescope. When using a camera, however, you should always wear corrective lenses to ensure the sharpest possible focus. If you have astigmatism, corrective lenses must be worn at all times. Figure 3-2 The decal on the end of the focus knob shows the correct rotational direction for focusing the CM-1100. Telescope Basics · 23 General Photography Hints Your Celestron CM-1100 can be used for both terrestrial and astronomical photography. Your Celestron CM-1100 has a fixed aperture and, as a result, a fixed f/ratio. To properly expose your subjects photographically you need to set your shutter speed accordingly. Most 35mm single lens reflex (SLR) cameras offer through-the-lens metering which lets you know if your picture is under or overexposed. This is more of a consideration when doing terrestrial photography, where exposure times are measured in fractions of a second. In astrophotography, the exposures are much longer, requiring that you use the "B" setting on your camera. The actual exposure time is determined by how long you keep the shutter open. To reduce vibration when tripping the shutter, use a cable release. Releasing the shutter manually can cause vibration, something that produces blurred photos. A cable release will keep your hands clear of the camera and telescope, thus reducing the possibility of shaking the telescope. Mechanical shutter releases can be used, though air type releases are best. Aligning the Finder The Celestron CM-1100 comes with an 9x50mm finder which helps in aiming the main telescope at distant objects that are hard to find in the narrow field of the telescope. The first number used to describe the finder is the power while the second number is the diameter of the objective lens in millimeters. This means the 9x50 finder is 9 power and has a 50mm objective lens. Incidentally, power is always compared to the unaided human eye. So a 9 power finder magnifies images nine times more than the human eye. 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. 2. Point your telescope at the object you selected and center it in the main optics of the telescope. 3. Check the finder to see where it is located in the field of view. 4. Adjust the screws on the finder bracket, tightening one while loosening another, until the cross hairs are centered on the target. 5. Tighten each set screw a quarter of a turn to ensure that they will not come loose easily. Figure 3-3 TOP: The image as seen through the telescope. BOTTOM: The image as seen through the finder. 24 · Telescope Basics 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 clutches. This will help to familiarize you with your telescope, thus making it easier to use at night. Daytime Observing As mentioned in the introduction, your Celestron CM-1100 telescope works well as a terrestrial spotting scope. When not used to examine objects in the night sky, it can be used to study objects here on Earth. WARNING ! NEVER POINT YOUR TELESCOPE AT THE SUN UNLESS YOU HAVE THE PROPER SOLAR FILTER. PERMANENT AND IRREVERSIBLE EYE DAMAGE MAY RESULT AS WELL AS DAMAGE TO YOUR TELESCOPE. ALSO, NEVER LEAVE YOUR TELESCOPE UNATTENDED DURING A DAYTIME OBSERVING SESSION, ESPECIALLY WHEN CHILDREN ARE PRESENT. 1. Find a distant object that is fairly bright. 2. Insert a low power eyepiece (one with a large focal length) into the telescope. 3. Adjust the R.A. and DEC clutch knobs if needed and point the telescope in the direction of the object you selected. 4. Locate the object in your finder. 5. Move the telescope -- by hand -- until the object is centered in the finder. 6. Look through the main optics and the object will be there (if you aligned the finder first). Try using different optional eyepieces to see how the field changes with various magnifications. Telescope Basics · 25 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 in the telescope by using landmarks. In the night sky many objects are not visible to the naked eye. To make things easier, you are better off starting with a bright object like the Moon or one of the planets. 1. Orient the telescope so that the polar axis is pointing as close to true north as possible. You can use a landmark that you know faces north to get you in the general direction. 2. Adjust the tripod legs until the mount is level. 3. Adjust the mount until the latitude indicator points to the latitude of the site from which you are observing. 4. Insert a low power eyepiece (i.e., one with a large focal length) into the telescope to give you the widest field possible. 5. Turn the clock drive on. 6. Loosen the right ascension and declination clutch knobs and point the telescope at the desired target. The Moon or one of the brighter planets is an ideal first target. 7. Locate the object in the finder, center it, and then look through the telescope. 8. Turn the focus knob until the image is sharp. 9. Take your time and study your subject. If observing the Moon, look for small details in the craters. That's all there is to using your Celestron CM-1100. However, don't limit your view of an object to a single eyepiece. After a few minutes, try using a different optional eyepiece, a more powerful one. This gives you an idea of how the field of view changes. Center your target and focus. Once again, if observing the Moon you will be looking at a few craters at the same time. NOTE: If not using the clock drive, the stars will appear to drift out of the field of view. This is due to the Earth's rotation. In fact, anything in the sky, day or night, will drift out unless the telescope has been polar aligned and the clock drive is running. There is more on this in the section on "Polar Alignment." 26 · Telescope Basics Calculating Magnification You can change the power of your Celestron CM-1100 telescope just by changing the eyepiece (ocular). To determine the magnification of your Celestron CM-1100, simply divide the focal length of the telescope by the focal length of the eyepiece used. In equation format, the formula looks like this: Focal Length of Telescope (mm) Magnification = -------------------------------- Focal Length of Eyepiece (mm) Let's say, for example, that you are using the standard 26mm eyepiece. To determine the magnification you simply divide the focal length of your Celestron CM-1100 (2800mm) by the focal length of the eyepiece (26mm). Dividing 2800 by 26 yields a magnification of 108 power. Although the power is variable, each instrument -- under average skies -- has a limit to the highest useful magnification. The general rule is that 60 power can be used for every inch of aperture. For example, the Celestron CM-1100 is 11" in diameter. Multiplying 11 by 60 gives a maximum useful magnification of 660 power. Although this is the maximum useful magnification, most observing is done in the range of 20 to 35 power for every inch of aperture which is 220 to 385 times for the CM-1100. Determining Field of View Determining the field of view is important if you want to get an idea of the angular size of the object you are observing. To calculate the actual field of view, divide the apparent field of the eyepiece (supplied by the eyepiece manufacturer) by the magnification. In equation format, the formula looks like this: Apparent Field of Eyepiece True Field = ------------------------------ Magnification As you can see, before determining the field of view, you must figure the magnification. Using the example in the previous section, we can determine the field of view using the same 26mm eyepiece. The 26mm Plössl eyepiece has an apparent field of view of 50°. Divide the 50° by the magnification, which is 108 power. This yields an actual field of .46°, or about one half of a degree. To convert degrees to feet at 1,000 yards, which is more useful for terrestrial observing, simply multiply by 52.5. Continuing with our example, multiply the angular field .46° by 52.5. This produces a linear field width of 24.2 feet at a distance of one thousand yards. The apparent field of each eyepiece that Celestron manufactures is found in the Celestron Accessory Catalog (#93685). Telescope Basics · 27 ASTRONOMY BASICS The following section deals with observational astronomy in general. It includes information on the night sky, polar alignment, and using your telescope for astronomical observing. The Celestial Coordinate In order to help find objects in the sky, astronomers use a celestial coordinate system which is similar to our geographical coordinate system here on Earth. System The celestial coordinate system has poles, lines of longitude and latitude, and an equator. For the most part, these remain fixed against the background stars. The celestial equator runs 360 degrees around the Earth and separates the northern celestial hemisphere from the southern. Like the Earth's equator, it bears a reading of zero degrees. On Earth this would be latitude. However, in the sky this is referred to as declination, or DEC for short. Lines of declination are named for their angular distance above and below the celestial equator. The lines are broken down into degrees, minutes and seconds of arc. Declinations south of the equator carry a minus sign (-) in front of the coordinate and those north of the celestial equator are either blank (i.e., no designation) or preceded by a plus sign (+). The celestial equivalent of longitude is called Right Ascension, or R.A. for short. Like the Earth's lines of longitude, they run from pole to pole and are evenly spaced 15 degrees apart. Although the longitude lines are separated by an angular distance, they are also a measure of time. Each line of longitude is one hour apart from the next. Since the Earth rotates once every 24 hours, there are 24 lines total. As a result, the R.A. coordinates are marked off in units of time. It begins with an arbitrary point in the constellation of Pisces designated as 0 hours, 0 minutes, 0 seconds. All other points are designated by how far (i.e., how long) they lag behind this coordinate after it passes overhead moving towards the west. Your Celestron CM-1100 telescope comes equipped with setting circles that translate the celestial coordinates into a precise location for the telescope to point. The setting circles will not work properly until you have polar aligned the telescope and aligned the R.A. setting circle. Figure 4-1 The celestial sphere seen from the outside showing R.A. and DEC. 28 · Astronomy Basics Motion of the Stars The daily motion of the Sun across the sky is familiar to even the most casual observer. This daily trek is not the Sun moving as early astronomers thought, but the result of the Earth's rotation. The Earth's rotation also causes the stars to do the same, scribing out a large circle as the Earth completes one rotation. The size of that circular path a star follows depends on where it is in the sky. Stars near the celestial equator form the largest circles rising in the east and setting in the west. Moving toward the north celestial pole, the point around which the stars in the northern hemisphere appear to rotate, these circles become smaller. Stars in the mid-celestial latitudes rise in the northeast and set in the northwest. Stars at high celestial latitudes are always above the horizon, and are said to be circumpolar because they never rise and never set. You will never see the stars complete one circle because the sunlight during the day washes out the starlight. However, part of this circular motion of stars in this region of the sky can be seen by setting up a camera on a tripod and opening the shutter for a couple hours. The processed film will reveal semicircles that revolve around the pole. (This description of stellar motion also applies to the southern hemisphere except all stars south of the celestial equator move around the south celestial pole.) Figure 4-2 All stars appear to rotate around the celestial poles. However, the appearance of this motion varies depending on where you are looking in the sky. Near the north celestial pole the stars scribe out recognizable circles centered on the pole (1). Stars near the celestial equator also follow circular paths around the pole. But, the complete path is interrupted by the horizon. These appear to rise in the east and set in the west (2). Looking toward the opposite pole, stars curve or arc in the opposite direction scribing a circle around the opposite pole (3). Astronomy Basics · 29 Polar Alignment In order for the telescope to track the stars, you must meet two criteria. First, you need a drive motor that moves at the same rate as the stars. The Celestron CM-1100 comes standard with a built-in drive motor designed specifically for this purpose. The second thing you need is to set the telescope's axis of rotation so that it tracks in the right direction. Since the motion of the stars across the sky is caused by the Earth's rotation about its axis, the telescope's axis must be made parallel to the Earth's. Polar alignment is the process by which the telescope's axis of rotation (called the polar axis) is aligned (made parallel) with the Earth's axis of rotation. Once aligned, a telescope with a clock drive will track the stars as they move across the sky. The result is that objects observed through the telescope appear stationary (i.e., they will not drift out of the field of view). If not using the clock drive, all objects in the sky (day or night) will slowly drift out of the field. This motion is caused by the Earth's rotation. Even if you are not using the clock drive, polar alignment is still desirable since it will reduce the number of corrections needed to follow an object and limit all corrections to one axis (R.A.). There are several methods of polar alignment, all of which work on a similar principle, but performed somewhat differently. Each method is considered separately, beginning with the easier methods and working to the more difficult. Although there are several methods mentioned here, you will never use all of them during one particular observing session. Instead, you may use only one if it is a casual observing session. Or, you may use two methods, one for rough alignment followed by a more accurate method if you plan on doing astrophotography. Definition: The polar axis is the axis around which the telescope rotates when moved in right ascension. This axis points the same direction even when the telescope moves in right ascension. Figure 4-3 30 · Astronomy Basics Finding the Pole Spring In each hemisphere, there is a point in the sky around which all the other stars appear to rotate. These points are called the celestial poles and are named for the hemisphere in which they reside. For example, in the northern hemisphere all stars move around the north celestial pole. When the telescope's polar axis is pointed at the celestial pole, it is parallel to the Earth's rotational axis. Many of the methods of polar alignment require that you know how to find the celestial pole by identifying stars in the area. For those in the northern hemisphere, finding the celestial pole is not too difficult. Fortunately, we have a naked eye star less than a degree away. This star, Polaris, is the end star in the handle of the Little Dipper. Since the Little Dipper (technically called Ursa Minor) is not one of the brightest constellations in the sky, it may be difficult to locate from urban areas. If this is the case, use the two end stars in the bowl of the Big Dipper (the pointer stars). Draw an imaginary line through them toward the Little Dipper. They point to Polaris. The position of the Big Dipper changes during the year and throughout the course of the night. When the Big Dipper is low in the sky (i.e., near the horizon), it may be difficult to locate. Observers in the southern hemisphere are not as fortunate as those in the northern hemisphere. The stars around the south celestial pole are not nearly as bright as those around the north. The closest star that is relatively bright is Sigma Octantis. This star is just within naked eye limit (magnitude 5.5) and lies about 59 arc minutes from the pole. For more information about stars around the south celestial pole, please consult a star atlas. The north celestial pole is the point in the northern hemisphere around which all stars appear to rotate. The counterpart in the southern hemisphere is referred to as the south celestial pole. Winter Summer Fall Figure 4-4 The position of the Big Dipper changes throughout the year and throughout the night. Definition: Figure 4-5 The two stars in the front of the bowl of the Big Dipper point to Polaris which is less than one degree from the true (north) celestial pole. Cassiopeia, the "W" shaped constellation is on the opposite side of the pole from the Big Dipper. The North Celestial Pole (N.C.P.) is marked by the "+" sign. Astronomy Basics · 31 Latitude Scales Latitude Scale 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 Celestron CM-1100 mount can be adjusted from 13 to 65 degrees (see figure 4-6). The constant, mentioned above, is a relationship between your latitude and the angular distance the celestial pole is above the northern (or southern) horizon; The angular distance from the northern horizon to the north celestial pole is always equal to your latitude. To illustrate this, imagine that you are standing on the north pole, latitude +90°. The north celestial pole, which has a declination of +90°, would be directly overhead (i.e., 90 above the horizon). Now, let's say that you move one degree south -- your latitude is now +89° and the celestial pole is no longer directly overhead. It has moved one degree closer toward the northern horizon. This means the pole is now 89° above the northern horizon. If you move one degree further south, the same thing happens again. You would have to travel 70 miles north or south to change your latitude by one degree. As you can see from this example, the distance from the northern horizon to the celestial pole is always equal to your latitude. If you are observing from Los Angeles, which has a latitude of 34°, then the celestial pole is 34° above the northern horizon. All a latitude scale does then is to point the polar axis of the telescope at the right elevation above the northern (or southern) horizon. To align your telescope: 1. Make sure the polar axis of the mount is pointing due north. Use a landmark that you know faces north. 2. Level the tripod. There is a bubble level built into the mount for this purpose. NOTE: Leveling the tripod is only necessary if using this method of polar alignment. Perfect polar alignment is still possible using other methods described later in this manual without leveling the tripod. 3. Adjust the mount in altitude until the latitude indicator points to your latitude. Moving the mount affects the angle the polar axis is pointing. For specific information on adjusting the equatorial mount, please see the section "Adjusting the Mount." This method can be done in daylight, thus eliminating the need to fumble around in the dark. Although this method does NOT put you directly on the pole, it will limit the number of corrections you will make when tracking an object. It will also be accurate enough for short exposure prime focus planetary photography (a couple of seconds) and short exposure piggyback astrophotography (a couple of minutes). Altitude Adjustment Knob Figure 4-6 The altitude scale allows for settings between 13 and 65 degrees. 32 · Astronomy Basics 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, you can simply point the polar axis of your telescope at Polaris. Although this is by no means perfect alignment, it does get you within one degree. Unlike the previous method, this must be done in the dark when Polaris is visible. 1. Set the telescope up so that the polar axis is pointing north. 2. Loosen the DEC clutch knob and move the telescope so that the tube is parallel to the polar axis. When this is done, the declination setting circle will read +90°. If the declination setting circle is not aligned, move the telescope so that the tube is parallel to the polar axis. 3. Adjust the mount in altitude and/or azimuth until Polaris is in the field of view of the finder. 4. Center Polaris in the field of the telescope using the fine adjustment controls on the mount. Remember, while Polar aligning, do NOT move the telescope in R.A. or DEC. You do not want to move the telescope itself, but the polar axis. The telescope is used simply to see where the polar axis is pointing. Like the previous method, this gets you close to the pole but not directly on it. The following methods help improve your accuracy for more serious observations and photography. Figure 4-7 One might think that pointing at the pole produces a parallax effect, thus skewing the telescope's axis of rotation with that of the Earth's. Polaris, however, is over 50 light years away, thus making any parallax effect negligible. (One light year is 6.4 trillion miles. To find the distance to Polaris in miles, multiply 6.4 trillion by 50!) Astronomy Basics · 33 The Polar Axis Finder The Polar Axis Finder is designed to minimize polar alignment time while maintaining maximum accuracy. The installation of this accessory is described in the section on "Installing the Polar Axis Finder." Here's how to use it: 1. Wait until it is dark enough to see Polaris with the unaided eye. 2. Place Polaris in the center of the crosshairs of the polar axis finder by adjusting the mounts latitude and azimuth controls (see figure 2-14 on page 16). 3. Rotate the polar scope until the small circle (located along the inner ring of the reticle) is positioned towards the celestial pole (see Figures 4-8 and 49). You may need to loosen the nylon tension screws on the polar finder bracket. Remember that the north celestial pole is located by moving away from Polaris in the direction of the last star (Alkaid) in the handle of the Big Dipper . 4. Adjust the mount in altitude and azimuth until Polaris is in the small circle indicating the celestial pole. When finished, the mount is accurately polar aligned. Put Polaris Here Figure 4-8 Figure 4-9 In this example the North Celestial Pole (NCP) is located approximately in the "11 O'clock" position relative to Polaris (Figure 4-9). Therefore, the polar finder reticle must be rotated to match the view as seen through the polar axis finder (Figure 4-8). Now, simply adjust the telescope's latitude and azimuth controls until Polaris is positioned in the small circle. 34 · Astronomy Basics 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. Although declination drift is quite simple and straightforward, it requires a great deal of time and patience to complete when first attempted. The declination drift method should be done after any one of the previously mentioned methods has been completed. To perform the declination drift method you need to choose two bright stars. One should be near the eastern horizon and one due south near the meridian. Both stars should be near the celestial equator (i.e., 0° declination). You will monitor the drift of each star one at a time and in declination only. While monitoring a star on the meridian, any misalignment in the east-west direction will be revealed. While monitoring a star near the east/west horizon, any misalignment in the north-south direction will be revealed. As for hardware, you will need an illuminated reticle ocular to help you recognize any drift. For very close alignment, a Barlow lens is also recommended since it increases the magnification and reveals any drift faster. When looking due south with the scope on the side of the mount, insert the diagonal so it points straight up. Insert a cross hair ocular and align the cross hairs to be parallel to declination and right ascension motion. Use ± 16x guide setting to check parallelism. First choose your star near where the celestial equator and the meridian meet. The star should be approximately ±1/2 hour of the meridian and ±5 degrees of the celestial equator. Center the star in the field of your telescope and monitor the drift in declination. · If the star drifts south, the polar axis is too far east. · If the star drifts north, the polar axis is too far west. Make the appropriate adjustments to the polar axis to eliminate any drift. Once you have managed to eliminate all drift, move to the star near the eastern horizon. The star should be 20 degrees above the horizon and ± 5 degrees of the celestial equator. · If the star drifts south, the polar axis is too low. · If the star drifts north, the polar axis is too high. Once again, make the appropriate adjustments to the polar axis to eliminate any drift. Unfortunately, the latter adjustments interact with the prior adjustments ever so slightly. So, repeat the process again to improve the accuracy checking both axes for minimal drift. Once the drift has been eliminated, the telescope is very accurately aligned. You will now be able to do prime focus deep-sky astrophotography for long periods. NOTE: If the eastern horizon is blocked, you may choose a star near the western horizon. However, you will have to reverse the polar high/low error directions. If using this method in the southern hemisphere, the procedure is the same as described above. However, the direction of drift is reversed. Astronomy Basics · 35 Aligning the R.A. Setting Circle Before you can use the setting circles to find objects in the sky, you need to align both the R.A. and DEC setting circles. In order to align the setting circle, you need to know the names of a few of the brightest stars in the sky. If you don't, they can be learned by using the Celestron Sky Maps (#93722) or consulting a current astronomy magazine. To align the R.A. setting circle: 1. Locate a bright star near the celestial equator. The farther you are from the celestial pole, the better your reading of the R.A. setting circle. The star you choose to align the setting circle with should be a bright one whose coordinates are known and easy to look up. (For a list of bright stars to align the R.A. setting circle, see the list at the back of this manual.) 2. Center the star in the finder. 3. Center the star in the field of the telescope. 4. Start the clock drive so that the mount tracks the star. 5. Look up the coordinates of the star. You can consult a star catalog or use the list at the end of this manual. 6. Rotate the circle until the proper coordinates line up with the R.A. indicator. The R.A. setting circle should rotate freely. The R.A. setting circle has a marker every four minutes with each hour labeled (see figure 4-10). The R.A. setting circle is now aligned and ready to use. The R.A. setting circle is clutched to the R.A. gear rotation. As long as the R.A. drive is operating, the circle does not need to be reset once indexed to the correct coordinate (i.e., once aligned). If the drive is ever turned off, then the R.A. setting circle must be reset once activated. While the R.A. setting circle tracks with the drive motor, it does not move when slewing the telescope. Figure 4-10 Setting the DEC Circle The declination setting circle is fixed in place and cannot be moved be hand. Once the mount is polar aligned with the DEC circle reading 90°, simply move the telescope in declination until the desired coordinance are reached. 36 · Astronomy Basics USING THE DRIVE The drive system uses a 5.625 diameter bronze gear with 180 teeth for incredibly accurate tracking. One of the most unique features of the drive is the Periodic Error Correction (PEC) function. This feature allows the drive system to "learn" the characteristics of the worm gear, and as a result, improve the tracking accuracy even more. This typically reduces the periodic error to 30 percent or less of the original error. The amount of improvement varies depending on guiding skill, atmospheric stability, the characteristics of the worm gear, and the accuracy of polar alignment. Following is a brief discussion of each feature. Powering Up the Drive In order to activate the drive, you must first plug it into an external power source. To supply power to your Celestron CM-1100, plug your Car Battery Adapter or optional AC Adapter into the outlet on the electronic console labeled "12 VDC." Then, plug the other end of the adapter into the appropriate power source (i.e., either AC or DC depending on the adapter used). Next, plug the R.A. and DEC cables into the electronic box. The DEC cable has a modular phone jack connector on each end. Plug one end into the DEC Motor receptacle on the electronics console and the other end into the declination motor. The R.A. cable has a modular phone jack connector at one end and a 5-pin connector at the other end. Attach the 5-pin connector over the 5 pins at the top of the electronics module (labled R.A. Motor), and then plug the phone jack connector into the R.A. motor. Once plugged into the proper power source, activate the drive by placing the ON/OFF switch in the "ON" position. Once activated, the drive begins tracking at sidereal rate, the default tracking rate. The LED next to the sidereal rate icon will illuminate. Figure 5-1 The CI-700 electronic console. Using the Drive · 37 Guide Speed This function allows you to select the speed at which the motor moves when corrections are made via the hand controller. Once the drive is activated, the default setting is .3 times sidereal rate. Press the Speed button to change the guiding rate. The selections are .3x, .5x, 8x, and 16x sidereal rate. For guiding, use either the .3x or .5x setting. These two rates allow optimal use with autoguiders. The faster settings -- 8x and 16x -- are perfect for positioning objects within the field of view. The telescope can also move at 20x speed WITHOUT changing any of the guide settings. To control the telecope at 20x speed, press the button that corresponds to the direction you want to move the telescope. While holding the button down, press the opposite directional button. For example, if you want to move the telescope west, hold the west button down and then press the east button. Conversely, if you want to move the telescope east, hold the east button down and then press the west button. This "fast-set" function also works in declination. It should be noted that the R.A. setting circle does not remain calibrated when using any of the slewing rates. NOTE: If the 20x speed is not functioning (but all other speeds do), it is probably due to low voltage from your power source. Figure 5-2 Tracking Rate Selection The drive has four basic rates: sidereal, solar, lunar and King (which is a modified sidereal rate that takes into account atmospheric refraction). While solar and lunar rates are obvious, sidereal and King rates require a little more explaining. Sidereal rate is based on a single rotation of the Earth which takes 1,436.5 minutes. An astronomer by the name of King discovered that atmospheric refraction affects the apparent motion of objects across the sky. The King rate takes into account this refraction caused by the Earth's atmosphere and is recommended for deep-sky astrophotography. For deep-sky observing, either King or sidereal rate is fine. Each of the tracking rates is represented by an icon. Sidereal rate is represented by a star ( ), solar rate by a sun ( ), lunar rate by a crescent moon ( ) and King rate by a crown ( ) . Next to each icon is an LED to indicate which rate has been selected. Once the power has been turned on, the drive tracks at sidereal rate, the default tracking rate. To change the tracking rate, press the "TRACK RATE" button. Pressing the button once changes the drive rate once. The rates are selected sequentially from bottom-to-top as listed above. Figure 5-3 Note that the PEC function does NOT have to be activated for the drive to work. However, once PEC is activated, the drive rate is locked on the one selected. You can not change rates until PEC is turned off. 38 · Using the Drive BC -- Backlash Correction The BC (Backlash Correction) function allows you to eliminate the backlash in the DEC motor when changing directions (i.e., from north to south or vice versa). Here's how it works. Each time you change the direction of the telescope in declination, the motor speeds up momentarily to take up any slack. The Tracking Rate and Guide Speed displays are used to regulate the "aggressiveness" of the backlash compensation. The best setting is determined by looking through the eyepiece while changing the direction of the DEC motor and then moving through the BC button settings until the backlash has been eliminated. To activate this function, press the BC button. Once activated, the .3x guide speed and sidereal tracking LED will flash rapidly. Use the east and west (left and right) buttons on the hand control to change the backlash compensation speed. Press the right hand control button and the next guide speed light (.5x) will illuminate. When the hand control button is pressed four times, the next Figure 5-4--The guide rate and tracking rate light ( ) will illuminate. Continue pressing the hand control tracking rate lights are used to buttons until the desired compensation speed is reached or until you reach the indicate the amount of backlash correction. highest setting (16x and ). Once the desired level is set, press the BC RATE button again to activate backlash correction. The BC must be reset each time you power up the drive. Periodic Error Correction (PEC) Periodic Error Correction, or PEC for short, is a system that improves the tracking accuracy of the drive. PEC is designed to improve photographic quality by reducing the amplitude of the worm errors. Using the PEC function is a two-step process. First, you must guide for at least eight minutes -- keeping the guide star centered on the cross hairs of your optional guiding eyepiece -- during which time the system records the corrections you make. (It takes the worm gear eight minutes to make one complete revolution, hence the need to guide for eight minutes). The second step is to play back the corrections you made during the recording phase. The microcomputer inside the electronic console does this automatically after one revolution of the worm gear. Periodic error is a slight oscillation in right ascension caused by imperfections in all drive gears. The cycle of the periodic error is equal to the rotation of the [worm] gear, in this case eight minutes. All telescope drives with gears have some periodic error. The periodic error of your Celestron CM-1100 is very slight to begin with. Keep in mind, this feature is for advanced astrophotographers and requires careful guiding. Here's how to use the PEC function most effectively. 1. Find a bright star relatively close to the object you want to photograph. 2. Insert a high power eyepiece with illuminated cross hairs into your telescope. Orient the guiding eyepiece cross hairs so that one is parallel to the declination axis while the other is parallel to the R.A. axis. 3. Center the guide star on the illuminated cross hairs, focus the telescope, and study the periodic movement. 4. Take a few minutes to practice guiding. This will help you familiarize yourself with the periodic error of the drive and the operation of the hand control box. Definition: Using the Drive · 39 5. Press the "PEC" button once to activate the mode. The LED will flash once a second for 5 seconds indicating you have five seconds to get back to the eyepiece and begin guiding before it begins recording. The .3x guiding rate is best for this function. NOTE: The star should stay centered on the cross hairs for a few seconds without using the hand controller before activating the PEC function. 6. Guide for eight minutes. Try not to overshoot corrections in right ascension. Ignore drift in declination. During the record phase, the LED flashes a little faster. After eight minutes, the system begins to play back the corrections made during the first eight minutes. When playing back, the LED stays on without blinking. NOTE: If you press the PEC button while it is in playback mode, you will lose the previously recorded information. Also, the fast slew functions are locked while the PEC function is activated. This eliminates the possibility of shifting the focus or moving the telescope suddenly during an exposure. The fast-set function is locked while the PEC function is activated. This eliminates the possibility of moving the telescope suddenly during an exposure. Once you have used the PEC function for awhile you may mistake its operation for the way the drive normally operates. The best way to see how well the PEC function works is to turn it off. PEC results improve with practice and patience. HC/CCD This outlet accepts the hand controller needed for guiding and moving the telescope. This outlet uses a modular phone-type jack. Push the connector on the cable into the outlet until the plastic tab clicks. To remove the cable, squeeze the plastic tab and pull away from the outlet. 12 V DC This outlet is used to supply power to the telescope. Your Celestron CM-1100 comes standard with a Car Battery Adapter. To install the adapter, plug the connector into the electronic console first, then the power source (automobile cigarette lighter receptacle). 40 · Using the Drive Northern/Southern Hemisphere Operation When using your Celestron CM-1100 in the southern hemisphere, there is a need to reverse the motors. Changing from northern hemisphere to southern hemisphere requires changing the polarity of the drive motor by changing the settings of the dip switches on the electronics board. To do this: 1. Remove the cover of the electronic console by removing the four screws (one in each corner). 2. Remove the two screws (one directly above the DEC motor jack and the other next to the On/Off indicator light) that attach the cover to the electronics board where the dip switches are located. 3. Locate the dip switches on the electronics board as shown on figure 5-5. 4. For operation in the southern hemisphere, set switch 4 to the OFF or down position (see Figure 5-6). The direction of the drive motor is now reversed and will work in the southern hemisphere. If going from the southern hemisphere to the northern hemisphere, simply change the switch back to the ON or up position. Figure 5-5 The Hand Controller Figure 5-6 The hand controller allows you to move the telescope in R.A. and DEC using the corresponding motors. This includes fine corrections for guided astrophotography and minor adjustments for centering objects in the field of view. The buttons on the hand controller are intentionally labeled in a rather vague manner. This is due to the fact that the direction of motion of the mount varies depending on how the telescope is oriented. Furthermore, these buttons are user definable to eliminate confusion when guiding. (For more information, see the section on "R.A./DEC Reverse.") Once again, to move the telescope at the 20x speed WITHOUT changing the guide setting, press the button that corresponds to the direction you want to move the telescope. While holding the button down, press the opposite directional button. For example, if you want to move the telescope west, hold the west button down and then press the east button. Conversely, if you want to move the telescope east, hold the east button down then press the west button. The fast-set function also works in declination. Using the Drive · 41 R.A./DEC Reverse As mentioned previously, the direction a particular button moves the mount varies depending on the telescope's orientation (i.e., whether it's on the east or west side of the mount). This can create confusion when guiding if you change the telescope's orientation during a given photographic session. To compensate for this, the direction of the R.A. and DEC buttons are changeable. To reverse the direction of either the R.A. and/or DEC buttons, change the switch setting of the appropriate axis (see Figure 5-7). Reverse switches Guiding Buttons Figure 5-7 Autoguiding On the top side of the hand controller you will find a phone jack outlet designated for use with an autoguider. Most CCD autoguiders will require a cable that attaches the autoguider to your telescope's drive controller via the hand controller outlet, rendering the hand controller inoperable. By plugging the autoguider cable directly into the hand controller, you have the ability to override the autoguider and make manual corrections with the hand controller buttons. 42 · Using the Drive CELESTIAL OBSERVING With your telescope set up, you are ready to use it for 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. In addition, little or no contrast can be seen during this phase. One of the best times to observe the Moon is during its partial phases (around the time of first or third quarter). Long shadows reveal a great amount of detail on the lunar surface. At low power you will be able to see most of the lunar disk at one time. The optional Reducer/Corrector lens allows for breathtaking views of the entire lunar disk when used with a low power eyepiece. Change to higher power (magnification) to focus in on a smaller area. Keep in mind that if you are not using the clock drive, the rotation of the Earth will cause the Moon to drift out of your field of view. You will have to manually adjust the telescope to keep the Moon centered. This effect is more noticeable at higher power. If you are using the clock drive and have polar aligned, the Moon will remain centered if using the lunar tracking rate. Consult your local newspaper or a current astronomy magazine to find out when the Moon will be visible. LUNAR OBSERVING HINTS · · To ensure accurate tracking, be sure to select the lunar tracking rate. Try using eyepiece filters to increase contrast and bring out more detail on the lunar surface. Observing the Planets Other easy targets in the night sky include the five naked eye planets. You can see Venus go through its lunar-like phases. Mars can reveal a host of surface detail and one, if not both, of its polar caps. You will be able to see the cloud belts of Jupiter and the great Red Spot (if it is visible at the time you are observing). In addition, you will also be able to see the moons of Jupiter as they orbit this gas giant. Saturn, with its beautiful rings, is easily visible at moderate power. All you need to know is where to look. Most astronomy publications tell where the planets can be found in the sky each month. King or sidereal rates work best for tracking the planets. Figure 6-1 This scanned drawing of Jupiter provides a good representation of what you can expect to see with moderate magnification during good seeing conditions. Celestial Observing · 43 Observing the Sun Although overlooked by many amateur astronomers, solar observation is both rewarding and fun. However, because the Sun is so bright, special precautions must be taken when observing our star so as not to damage your eyes or your telescope. Never project an image of the Sun through the telescope. Because of the folded optical design, tremendous heat buildup will result inside the optical tube. This can damage the telescope and/or any accessories attached to the telescope. For safe solar viewing, use a solar filter. These filters reduce the intensity of the Sun's light, making it safe to view. With these filters you can see sunspots as they move across the solar disk and faculae, which are bright patches seen near the Sun's edge. Be sure to cover the lens of the finder or completely remove the finder when observing the Sun. This will ensure that the finder itself is not damaged and that no one looks through it inadvertently. SOLAR OBSERVING HINTS · The best time for observing the Sun is in the early morning or late afternoon when the air is cooler. To locate the Sun without a finder, watch the shadow of the optical telescope tube until it forms a circular shadow. To ensure accurate tracking, be sure to select the solar tracking rate. WARNING: · · 44 · Celestial Observing Observing Deep-Sky Objects Deep-sky objects are simply those objects outside the boundaries of our solar system. They include star clusters, planetary nebulae, diffuse nebulae, double stars, and other galaxies outside our own Milky Way. The Celestron Sky Maps (#93722) can help you locate the brightest deep-sky objects. You can use your setting circles or "star hop" to an object from an area with which you are familiar. Most deep-sky objects have a large angular size. Therefore, low-to-moderate power is all you need to see them. Visually, they are too faint to reveal any color seen in long exposure photographs. Instead, they have a black and white appearance. And, because of their low surface brightness, they should be observed from a dark sky location. Light pollution around large urban areas washes out most nebulae making them difficult, if not impossible, to observe. Light Pollution Reduction filters help reduce the background sky increasing contrast. Using Your 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. Move the telescope in R.A. until the indicator points to the correct coordinate (do NOT move the R.A. circle). The telescope will track in R.A. as long as the clock drive is operating. 5. Look through the finder to see if you have located the object. 6. Center the object in the finder. 50 60 70 80 6 7 7. Look in the main optics using a low power eyepiece; the object should be there. 8. Repeat the process for each object observed throughout the observing session. You may not be able to see fainter objects in the finder. When this happens, gradually sweep the telescope around until the object is visible. The declination setting circle is scaled in degrees while the R.A. setting circle is incremented in minutes with a marker every five minutes (see figure 6-2). As a result, the setting circles will get you close to your target, but not directly on it. Also, the accuracy of your polar alignment will also affect how accurately your setting circles read. It should be noted that the R.A. setting circle does not remain calibrated when using any of the slewing rates. At the end of this manual there is a list of deep-sky objects well within reach of your Celestron CM-1100 telescope. Figure 6-2 The R.A. setting circle (top) and the DEC circle (bottom). Celestial Observing · 45 Star Hopping Another way to find deep-sky objects is by star hopping. Star hopping is done by using bright stars to "guide" you to an object. Here are the directions for two popular objects. The Andromeda Galaxy, M31, is an easy 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 () Andromedae. 3. Move northeast approximately 7°. There you will find two stars of equal brightness -- Delta () and Pi () Andromedae -- about 3° apart. 4. Continue in the same direction another 8°. There you will find two stars -- Beta () and Mu (µ) Andromedae -- about 3° apart. 5. Move 3° northwest -- the same distance between the two stars -- to the Andromeda galaxy. It is easily visible in the finder. Figure 6-3 Star hopping to the Andromeda Galaxy is a snap to find since all the stars needed to do so are visible to the naked eye. Note that the scale for this star chart is different from the one on the following page which shows the constellation Lyra. 46 · Celestial Observing