Celestron 52260 Telescope User Manual
Contents
1. fECESTIROIT e C80 HD Refractor Telescope e C102 HD Refractor Telescope e C114 HD Reflector Telescope e C150 HD Reflector Telescope e CG 4 Equatorial Mount Models 21077 21016 31027 31056 91510 INSTRUCTION MANUAL IDENTIFYING PARTS OF FIGURE 1 1 Star Diagonal Refractors only 13 Latitude Scale 2 Eyepiece 14 Altitude Adjustment Screw 3 Finderscope 15 Tripod Mounting Head 4 Finder Bracket 16 Tripod 5 _Focuser 17 Tripod Support Brace 6 Tube Rings 18 Counterweight Shaft 7 Objective Cap 19 Counterweight s 8 Optical Tube Platform 20 Azimuth Adjustment Screw 9 DEC Setting Circle 21 R A Slow Motion Knob 10 R A Clamp 22 DEC Clamp 11 R A Setting Circle 23 DEC Slow Motion Knob 12 Polar Finder Optional 24 Accessory Tray 25 Accessory Tray Mounting Screws Figure 1A C80 HD amp C102 HD Figure 1B Figure 1C CG 4 EQ Mount INTRODUCTION Congratulations on your purchase and welcome to the Celestron world of astronomy If you re a newcomer to the hobby of astronomy some of the terms and telescope components described in this instruction manual may be new to you This manual is designed to instruct you in the proper use of your Celestron C80 HD Refractor C102 HD Refractor C114 HD 4 5 Newtonian or C150 HD Newtonian as well as the CG 4 Equatorial Mount To assist you in assembling and operating your telescope take time to review thi2. areas lf this is the case use the two end stars in the bowl of the Big Dipper Draw an imaginary line through them toward the Little Dipper They will point to Polaris The position of the Big 10 Dipper will change 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 Little Dipper e e Big s Dipper Cassiopeia N C P Polaris Li North Star Figure 7 To make finding and tracking the stars easier a rough polar alignment is required l The right ascension polar axis should be pointed towards the North Pole see figure 7 2 The equatorial mount should be level 3 Set the latitude of the telescope to the latitude of your observing location by turning the azimuth adjustment screws 14 on the mount The latitude of your observing location corresponds to the altitude that Polaris will appear to be above the horizon For example If you are observing from Los Angeles which has a latitude of 34 then the celestial pole and Polaris will be 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 4 Release the DEC clamp 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
3. the length of the optical tube 2 Locate the two screws on either end of the platform for the optical tube 8 3 Hold the telescope up to the mount and slide the mounting rings until they are over the screws on the mounting platform 4 Place the flat portion of the ring over the mount so that the hole in the ring is over the screw protruding out of the mounting platform 5 Tighten the knobs underneath the mounting platform to secure the rings 6 Tighten the knobs on the side of the mounting rings to prevent the telescope from sliding forward or backward These can be loosened later to reposition the telescope during the balancing process Balancing the Telescope To eliminate undue stress on the mount the telescope should be properly balanced around the polar axis In addition proper balancing is crucial for accurate tracking if using a clock drive To balance the mount Release the R A Clamp and position the telescope off to one side of the mount see figure 2a GRADUALLY release the telescope to see which way it rolls Loosen a counterweight lock screw and slide the counterweight to a point where it balances the scope i e the telescope remains stationary when the R A clamp is released Tighten the counterweight lock screw The scope is properly balanced in right ascension Figure 2a Figure 2b The telescope should also be balanced in declination to prevent any sudden movement when the Decl
4. Diagonal for 21077 amp 21016 Loosen the thumb screw on the eyepiece holder located on the focuser draw tube Slide the smaller end of the diagonal without the thumb screw into the focuser tube Tighten the thumb screw to hold the diagonal in place Ocular Loosen the thumb screw on the eyepiece holder or 1 diagonal for 21077 amp 21016 Slide the barrel of the eyepiece into the eyepiece holder and tighten the thumb screw to hold the eyepiece in place Aligning the Finderscope Accurate alignment of the finderscope makes it easy to find objects with the telescope especially celestial objects To make aligning the finderscope as easy as possible this procedure should be done in the daytime when it is easy to find and identify objects To align the finder 1 Choose a target that is in excess of one mile away This will eliminate any possible parallax effect between the telescope and finderscope 2 Point the telescope at your target and center it in the main optics of the telescope You may have to move the telescope slightly to center your target 3 Adjust the screws on the finderscope bracket tightening one while loosening another until the cross hairs are centered on the target seen through the telescope 4 Tighten the lock nuts to secure the position of the finderscope Image orientation through the finder will be inverted i e upside down and backwards left to right This is normal for any finderscope that is us
5. make contact with the finderscope body 4 Locate the mounting bracket near the front open end of the telescope 5 Loosen the set screw on the mounting bracket on the telescope 6 Slide the finder bracket attached to the finderscope into the mounting bracket on the telescope 7 The finderscope bracket will slide in from the back The finderscope should be oriented so that the objective lens is toward the front open end of the telescope see figure 3 8 Tighten the set screw on the mounting bracket to hold the finderscope in place Finderscope Figure 3 Attaching the Finderscope for 31027 1 Remove the nuts from the studs where the finderscope will mount see figure 4 2 Mount the finderscope bracket 4 by mounting the bracket over the studs protruding from the tube and tightening it down with the supplied nuts 3 Slide the rubber O ring over the eyepiece end of the finderscope and roll it 2 3 of the way up the finderscope 4 Insert the eyepiece end of the finderscope through the bracket until the O ring presses tightly between the finder and the inside of the bracket 5 Tighten the three adjustment screws until they make contact with the finderscope body The finderscope is now installed and only needs to be aligned before it is used Attaching the Accessories In order to use your telescope there are some standard accessories which must first be installed The installation of each is described 1
6. telescope To install the Counterweight Bar Retract the counterweight bar lock nut by turning it counterclockwise This will expose the threads on the end of the Counterweight Bar Thread the Counterweight Bar into the mount completely It threads into the mount opposite the telescope 1 Tighten the lock nut fully for added support 2 The Counterweight Bar is now installed 3 Installing the Counterweights With the counterweight bar in place you are ready to attach the counterweights l Remove the safety thumbscrew on the end of the counterweight bar 2 Loosen the counterweight lock screw on the counterweight itself so that the central hole of the counterweight is unobstructed 3 Slide the counterweight onto the counterweight bar Move it high enough to allow room for the second weight if included 4 Tighten the counterweight lock screw to hold it in position 5 Repeat this process for the second weight 6 Replace the thumbscrew on the end of the counterweight bar The thumbscrew will prevent the counterweight s from sliding off the bar should they ever become loose Attaching the Optical Tube Before you attach the optical tube make sure that the declination and right ascension clamps are tight The optical tube attaches to the mount via two rings that are mounted on the tube of the telescope To mount the telescope tube 1 Loosen the knobs on the side of the rings This will allow you to slide the mounting rings
7. the telescope so that the tube is parallel to the polar axis 11 5 Using the altitude and azimuth adjustment screws 14 amp 20 move the mount until Polaris is in the field of view of the finderscope Rough adjustments in azimuth can be made by moving the tripod 6 Center Polaris using the altitude and azimuth controls Remember do not move the telescope in R A and DEC You want to adjust the direction the polar axis is pointing and you are using the telescope to see where the polar axis is pointing This gets you close to the pole but not directly on it In order to improve your accuracy for more serious observations and photography Celestron offer an optional Polar Axis Finderscope 94221 that fits into the polar axis of the mount Aligning the R A Setting Circle Before you can use the setting circles to find objects in the sky you need to align the R A setting circle The declination setting circle is aligned during the process of polar alignment In order to align the R A setting circle you will 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 Locate a bright star near the celestial equator The farther you are from the celestial pole the better your reading on the R A setting circle will be The star you choose to align the setting circle with shoul
8. 60 circle bisecting the celestial sphere into the northern celestial hemisphere and the southern celestial hemisphere Like the Earth s equator it is the prime parallel of latitude and is designated 0 The celestial parallels of latitude are called coordinates of declination Dec and like the Earth s latitudes they are named for their angular distances from the equator These distances are measured in degrees minutes and seconds of arc There are 60 minutes of arc in each degree and 60 seconds of arc in each arc minute Declinations north of the celestial equator are and declinations south are The north pole is 90 and the south pole is 90 NORTH POLE The celestial meridians of longitude are called coordinates of right ascension R A and like the Earth s longitude meridians they extend from pole to pole There are 24 major RA coordinates evenly spaced around the 360 equator one every 15 Like the Earth s longitudes R A coordinates are a measure of time as well as angular distance We speak of the Earth s major longitude meridians as being separated by one hour of time because the Earth rotates once every 24 hours one hour 15 The same principle EL applies to celestial longitudes since the celestial sphere Cra Ca appears to rotate once every 24 hours Right ascension hours are also divided into minutes of arc and seconds of arc with each hour having 60 minutes of arc and each arc minute being
9. R A indicator must stay between the 18h 50m mark and the 19h 00m mark on the R A setting circle Look through the telescope and the Ring Nebula should be within the field of view if you are using a low power eyepiece assuming you have already set the DEC Telescope Maintenance With proper care your telescope should rarely need any maintenance work 1 When not in use always replace all lens covers to keep dust and contaminants off the optical surfaces 2 A small amount of dust on any optical surface is OK If the dust builds up then use a can of compressed air and then a camel s hair brush to remove the dust 3 Ifthe mirrors or lenses need cleaning they should be cleaned by a professional Either have your instrument serviced by a telescope repair facility or return it to the factory 4 Collimation or alignment of the optical system is done at the factory before shipment Collimation for the 31027 and 31056 only 1 If your telescope has received very rough handling during transport or is dropped it may need collimation To check if your telescope is in collimation the sketch below will help you If you look into the eyepiece adapter without an eyepiece this is what you should see If the reflection of your eye is off center then collimation is necessary 2 If your telescope is out of collimation it can be re collimated by loosening the three Phillips head screws located on the rear cell of the telescope tube and adju
10. d be a bright one whose coordinates are known and easy to look up Center the star in the finderscope Look through the main telescope and see if the star is in the field If not find it and center it If you purchased an optional motor drive start it now so that it will track the star Look up the coordinates of the star Rotate the circle until the proper coordinates line up with the R A indicator the zero mark on the vernier scale The R A setting circle should rotate freely NOTE Because the R A setting circle does NOT move as the telescope moves in R A the setting circle must be aligned each time you want to use it to find an object This holds true even if you are using an optional motor drive However you do not need to use a star each time Instead you can use the coordinates of the object you are currently observing Once the setting circles are aligned you can use them to find any objects with known coordinates The accuracy of your setting circles is directly related to the accuracy of your polar alignment Select an object to observe Use a seasonal star chart 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 Look up the coordinates in an atlas or reference book Hold the telescope and release the DEC clamp Move the telescope in declination until the indicator is pointing at the correct declination coordinate Lock the declina
11. d head On one side of the tripod head there is an N which signifies North This side of the tripod will face north when setting up for an astronomical observing session Above the N is a metal peg about 3 4 high that points straight up Place the equatorial mount head on top of the tripod head so that the metal peg fits between the two 4 azimuth adjustment bolts It may be necessary to partially unscrew the bolts to allow the metal peg to fully extend into the altazimuth housing 4 Tighten the knob located on the underside of the tripod head This will hold the equatorial mount firmly to the tripod head Attaching the Accessory Tray Next attach the accessory tray to the tripod Locate the accessory tray and the three wingnut screws to attach the tray 1 Place the accessory tray on the center support brace of the tripod and align the holes on the tray with those on the support brace 2 Insert the wingnut screws through the bottom of the tripod support brace and thread them into the accessory tray holes With the accessory tray in place the tripod will be much more stable making it easier to attach the telescope Installing the Counterweight Bar With the mount securely in place you are ready to attach some of the accessories the telescope tube will be added last Start with the Counterweight Bar and Counterweights Used to balance the telescope the Counterweight Bar attaches to the opposite side of the mount as the
12. divided into 60 arc seconds Figure 5 Astronomers prefer the time designation for R A coordinates even though the coordinates denote locations on the celestial sphere because this makes it easier to tell how long it will be before a particular star will cross a particular north south line in the sky So R A coordinates are marked off in units of time eastward from an arbitrary point on the celestial equator in the constellation Pisces The prime R A coordinate which passes through this point is designated O hours O minutes O seconds We call this reference point the vernal equinox where it crosses the celestial equator All other coordinates are names for the number of hours minutes and seconds that they lag behind this coordinate after it passes overhead moving westward Given the celestial coordinate system it now becomes possible to find celestial objects by translating their celestial coordinates using telescope pointing positions For this you use setting circles for R A and Dec to find celestial coordinates for stellar objects which are given in star charts and reference books Polar Alignment Polar alignment is the process by which the telescope s axis of rotation is aligned made parallel with the Earth s axis of rotation see figure 7 Once aligned a telescope with a motor drive will track the stars as they move across the sky The result is that objects being observed through the telescope appear stationary i e they
13. ed straight through Because of this it may take a few minutes to familiarize yourself with the directional change each screw makes on the finderscope Telescope Basics Calculating Magnification The magnification or power of a telescope is variable depending upon the focal length of the eyepiece being used along with the focal length of the telescope To calculate the magnification we use the following formula FL tel Magnification HEU ESCOpe FL eyepiece where FL telescope is the focal length of the telescope and FL eyepiece is the focal length of the eyepiece For example if the focal length of the telescope is 910mm and you use a 20mm eyepiece your magnification is 910 20 46x There are numerous optional eyepieces that are available to expand your range of magnification There are various types of eyepieces of varying quality to choose from The Celestial Coordinate System The celestial coordinate system is an imaginary projection of the Earth s geographical coordinate system onto the celestial sphere which seems to turn overhead at night This celestial grid is complete with equator latitudes longitudes and poles The Earth is in constant motion as it rotates on its axis Actually the celestial coordinate system is being displaced very slowly with respect to the stars This is called precession and is caused by gravitational influences from the Sun Moon and other celestial bodies The celestial equator is a full 3
14. he night sky They include all the constellations with the brighter deep sky objects On the front cover is a rotating planisphere which indicates when specific constellations are visible Flashlight LED 93588 Uses red LED s to allow reading star maps and locating telescope accessories and controls without ruining you night vision 15 Motor Drive 93517 This single axis unit runs off D cell batteries It compensates for the Earth s rotation keeping celestial objects centered in the field of view This makes observing much more enjoyable as it eliminates the constant usage of the slow motion controls A dual axis model 93522 is also available Eyepieces A whole assortment of various sizes of 1 4 eyepieces are available to give you a wide range of magnifications Eyepiece filters A line of filters are available for 1 1 4 eyepieces to enhance your visual observations of the Moon and planets Collimation Tool for Newtonians 94183 A helpful aid to collimating your telescope Provided is a simple tool and detailed instructions Polar Axis Finderscope 94221 This useful accessory helps speeds accurate polar alignment by using an etched reticle for finding the North Celestial Pole T Adapters Allows you to take short exposure photos of the Moon It requires a 35mm SLR camera and a T Ring for your brand of camera Other Numerous other accessories are available See the Celestron Accessory Catalog 93685 or ask y
15. hich has been discontinued from its product line with a new product of comparable value and function This warranty shall be void and of no force of effect in the event a covered product has been modified in design or function or subjected to abuse misuse mishandling or unauthorized repair Further product malfunction or deterioration due to normal wear is not covered by this warranty CELESTRON DISCLAIMS ANY WARRANTIES EXPRESS OR IMPLIED WHETHER OF MERCHANTABILITY OF FITNESS FOR A PARTICULAR USE EXCEPT AS EXPRESSLY SET FORTH HEREIN THE SOLE OBLIGATION OF CELESTRON UNDER THIS LIMITED WARRANTY SHALL BE TO REPAIR OR REPLACE THE COVERED PRODUCT IN ACCORDANCE WITH THE TERMS SET FORTH HEREIN CELESTRON EXPRESSLY DISCLAIMS ANY LOST PROFITS GENERAL SPECIAL INDIRECT OR CONSEQUENTIAL DAMAGES WHICH MAY RESULT FROM BREACH OF ANY WARRANTY OR ARISING OUT OF THE USE OR INABILITY TO USE ANY CELESTRON PRODUCT ANY WARRANTIES WHICH ARE IMPLIED AND WHICH CANNOT BE DISCLAIMED SHALL BE LIMITED IN DURATION TO A TERM OF TWO YEARS FROM THE DATE OF ORIGINAL RETAIL PURCHASE Some states do not allow the exclusion or limitation of incidental or consequential damages or limitation on how long an implied warranty lasts so the above limitations and exclusions may not apply to you This warranty gives you specific legal rights and you may also have other rights which vary from state to state Celestron reserves the right to modify or discontinue without prior not
16. ice to you any model or style telescope If warranty problems arise or if you need assistance in using your telescope contact Celestron Customer Service Department 2835 Columbia Street Torrance CA 90503 Tel 310 328 9560 Fax 310 212 5835 Monday Friday 8SAM 4PM PST This warranty supersedes all other product warranties NOTE This warranty is valid to U S A and Canadian customers who have purchased this product from an Authorized Celestron Dealer in the U S A or Canada Warranty outside the U S A and Canada is valid only to customers who purchased froma Celestron Distributor or Authorized Celestron Dealer in the specific country and please contact them for any warranty service 17
17. ination clamp is released To balance the telescope in Declination Release the R A clamp and rotate the telescope so that it is on one side of the mount i e as described above for balancing the mount in R A Lock the R A clamp to hold the telescope in place Release the DEC clamp and position the telescope so that it is parallel to the ground GRADUALLY release the telescope tube to see which way it rolls Loosen the screws that hold the telescope inside the mounting rings and slide the telescope either forward or backwards until it remains stationary when the DEC clamp is released see figure 2b Tighten the screws that hold the telescope in the mounting rings The telescope is now properly balanced in declination Attaching the Finderscope for 21077 21016 amp 31056 To install the finderscope onto the telescope you must first mount the finderscope through the finder bracket and then attach it to the telescope Toward the front of the telescope tube near the focusing assembly there is a small bracket with a set screw in it This is where the finderscope bracket will be mounted To install the finderscope 1 Slide the rubber O ring over the eyepiece end of the finderscope and roll it 2 3 of the way up the finderscope 2 Insert the eyepiece end of the finderscope through the bracket until the O ring presses tightly between the finder and the inside of the bracket 3 Tighten the three adjustment screws until they
18. our Celestron dealer for details 16 CELESTRON TWO YEAR WARRANTY A Celestron warrants this telescope to be free from defects in materials and workmanship for two years Celestron will repair or replace such product or part thereof which upon inspection by Celestron is found to be defective in materials or workmanship As a condition to the obligation of Celestron to repair or replace such product the product must be returned to Celestron together with proof of purchase satisfactory to Celestron B The Proper Return Authorization Number must be obtained from Celestron in advance of return Call Celestron at 310 328 9560 to receive the number to be displayed on the outside of your shipping container All returns must be accompanied by a written statement setting forth the name address and daytime telephone number of the owner together with a brief description of any claimed defects Parts or product for which replacement is made shall become the property of Celestron The customer shall be responsible for all costs of transportation and insurance both to and from the factory of Celestron and shall be required to prepay such costs Celestron shall use reasonable efforts to repair or replace any telescope covered by this warranty within thirty days of receipt In the event repair or replacement shall require more than thirty days Celestron shall notify the customer accordingly Celestron reserves the right to replace any product w
19. roblem arises when the R A indicator zero mark is in between two of the marks on the R A setting circle If this is the case you will notice that along the vernier scale one of the marks will line up with one of the marks on the setting circle This mark indicates the number of minutes that should be added to the R A reading of the indicator Since the indicator is between two R A marks add the minutes to the lower value that the R A indicator falls between For example let s say the R A indicator zero mark on the vernier is just left of the 5h 40m mark This would place it between the 5h 40m mark and the 5h 50m mark If you look down the vernier scale you will see that the 4 is the only mark to line up with any of the marks on the R A setting circle see figure 8 This means that you are 4 minutes to the left of the 5h and 40m mark or more simply at 5h and 44m Figure 8 Here s how to use the vernier Look up the coordinates of the object you want to observe For our example we will use the Ring Nebula M57 which is at 18h 53m right ascension Release the R A clamp and rotate the telescope until the R A indicator is between the 18h 50m mark and the 19h 00m mark on the R A setting circle Lock the R A clamp to hold the telescope in place 13 Move the telescope in R A using the slow motion control handle until the three on the vernier scale lines up with one of the marks on the R A setting circle Remember the
20. s manual and the parts diagram listed in Figure 1 WARNING NEVER LOOK AT THE SUN WITH YOUR TELESCOPE OR ITS FINDERSCOPE PERMANENT AND IRREVERSIBLE EYE DAMAGE MAY RESULT AS WELL AS DAMAGE TO YOUR TELESCOPE HOWEVER YOU MAY ENJOY LOOKING AT THE SUN IF YOU HAVE A SAFE METHOD OF DOING SO A SOLAR FILTER IF USING THE SOLAR FILTER MAKE SURE THE FINDERSCOPE IS COVERED TELESCOPE ASSEMBLY The telescopes and all items are packed in one box Included are e Telescope Optical Tube German Equatorial Mount Adjustable Aluminum Tripod 6x30 Finderscope and Bracket Counterweight Shaft and Counterweights 3 6 Kg and 1 8 Kg for reflector models 31027 31056 and refractor model 21016 3 6 kg only for refractor model 21077 and CG 4 Eq Mount 91510 Tripod Accessory Tray Declination Slow Motion Knob Right Ascension Slow Motion Knob 20mm Plossl Eyepiece 1 4 Mirror Diagonal Except 31027 amp 31056 Setting Up the Tripod 1 Locate the tripod head see figure 1 Attach each leg one by one to the tripod head by aligning the holes at the top of each leg with the holes in the tripod head Slide a bolt through each of the legs and the tripod head and secure at the other end with a wing nut NOTE this may have been pre assembled at the factory 2 Now that the tripod legs are attached stand the tripod up and spread the legs until the center leg support is fully extended 3 The equatorial mount which holds the telescope attaches to the tripo
21. sting the three knurled knobs until the secondary mirror is centered in the reflection of the primary mirror 14 The best way to re collimate is with a good collimation tool Celestron offers a Newtonian Collimation Tool 94183 with detailed instructions that make it an easy chore Technical Specifications C80 HD 21077 C102 HD C114 HD C150 HD 21016 31027 31056 Optical System Achromat Achromat Newtonian Newtonian Refractor Refractor Reflector Reflector Coating Fully Multi Coated Fully Multi Multi Coated Multi Coated Coated Aperture 80mm 102mm 114mm 150mm Focal Length 900mm 1000mm 900mm 1000mm F ratio f 11 f 10 f 8 F 7 Magnification with standard eyepiece 45x 50x 45x 50x Highest Useful Power Magnification 189x 241x 269x 354x Resolution in arc seconds Dawes 1 45 1 14 1 02 0 77 Light Gathering Power 131 212 265 459 Limiting Visual Magnitude 12 125 13 13 5 Angular Field of View 1 1 1 1 1 1 Linear Field of View at 1000 yds a 53 57 93 Optical Tube Length 35 38 5 35 19 25 Weight Optical Tube 6 lbs 8 0 lbs 6 lbs 13 Ibs Equatorial Mount with counterweight 23 Ibs 28 Ibs 28 Ibs 28 lbs Note All specifications are using the standard accessories These specifications are approximate and subject to change without notice OPTIONAL ACCESSORIES Celestron International offers a wide assortment of optional accessories to expand your interests Sky Maps 93722 Invaluable when learning t
22. tion clamp to prevent the telescope from moving 12 10 11 Hold the telescope and release the R A clamp Move the telescope in R A until the indicator points to the correct coordinate Lock the R A clamp to prevent the telescope from slipping in R A The telescope will track in R A as long as the motor drive is operating Look through the finderscope to see if you have located the object Center the object in the finder Look in the main optics and the object should be there For some of the fainter objects you may not be able to see them in the finder When this happens it is a good idea to have a star chart of the area so that you can star hop through the field to your target This process can be repeated for each object throughout any given night Using the R A Vernier Scale To increase the accuracy of the R A setting circle the mount comes with a vernier This device allows you to get more precise readings down to one minute of right ascension Before we go into the specifics on how to use the vernier let s take a look at the scale and learn how to read it First the zero 0 mark on the vernier is the R A indicator and will hereafter be referred to as such It is on the extreme right end of the vernier scale with the other numbers increasing as you move toward the left If the R A indicator is right on one of the marks of the R A setting circle then that is the coordinate the telescope is pointing at The p
23. will not drift out of the field of view If your telescope does not use a motor drive all celestial 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 a motor 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 are performed somewhat differently For each hemisphere there is a point in the sky around which all the other stars appear to rotate These points are called the celestial poles and are named for the hemisphere in which they reside For example in the northern hemisphere all stars appear to move around the north celestial pole see figure 6 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 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 especially from urban
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