Celestron 31056, 31058 instruction manual Using the Setting Circles

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Using the Setting Circles

Once the setting circles are aligned you can use them to find any object with known coordinates.

1. Select an object to observe. Use a seasonal star chart or planisphere to make sure the object you chose is above the horizon. As you become more familiar with the night sky, this will no longer be necessary.

2. Look up the coordinates in an atlas or reference book.

3. Move the telescope in declination until the indicator is pointing at the correct declination coordinate.

4. Move the telescope in R.A. until the indicator points to the correct coordi- nate (do NOT move the R.A. circle). The telescope will track in R.A. as long as a motor drive is operating and the R.A. clamp is in the locked position.

5. Look through the finder to see if you have located the object.

6. Center the object in the finder.

7. Look in the main optics using a low power eyepiece; the object should be there. The telescope will track in R.A. as long as the motor drive is operating.

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 fifth minute. 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.

At the end of this manual there is a list of deep-sky objects well within reach of your Celestron telescope.

42 • Celestial Observing

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Contents C150-HD and G-8N Newtonian Page B L E N T E N T S Celestial Photography T R O D U C T I O N How to Use this Manual Word of Caution Newtonian Optical System S E M B L I N G Y O U R N E W T O N I a N T E L E S C O P E Unpacking Your G-8NG-8N C150-HD Setting Up the Tripod Adjusting the Tripod HeightAttaching the Accessory Tray Attaching the Equatorial Mount They are needed later for polar alignmentAttaching the R.A. Slow Motion Knob Attaching the Declination Slow Motion Knob Attaching the Counterweight Bar and Counterweight Attaching the Telescope to the Mount For G-8N Attaching the Telescope to the Mount For C150- HD Removing the Lens Cap Balancing the Telescope in R.ABalancing the Telescope in DEC CompletelyG-8N C150-HD Installing the Finderscope Installing the Eye- piece Technical Specifications Image Orientation ActualVeiw NewtonianViewFocusing Aligning the Finder Your First Look Daytime ObservingNighttime Observing Calculating Magnification Determining Field of View T R O N O M Y B a S I C S Celestial Coordi- nate SystemMotion of the Stars Polar Alignment DefinitionFinding the Pole Latitude Scales Pointing at Polaris Declination Drift Aligning the R.A Setting Circle Polar Alignment FindersL E S T I a L O B S E R V I N G Observing the Moon PlanetsObserving the S u n Observing Deep-Sky ObjectsUsing the Setting Circles Star Hopping Celestial Observing Sky Illumination Viewing ConditionsTransparency SeeingCelestial Observing L E S T I a L P H O T O G R a P H Y Lunar Phase ISO Crescent Quarter 125 Full 250 Short Exposure Prime F o c u sPiggyback Celestial Photography Care and Cleaning of the Optics Collimation L E S C O P E M a I N T E N a N C EOr back out the holder screws more than one 1 to two 2 turns T I O N a L a C C E S S O R I E S Optional Accessories Single Axis Motor Drive System #93518 Themessiercatalog Great Orion Nebula Elliptical Galaxy List of Bright Stars For Further Reading Celestron ONE Year Warranty