Celestron C80ED-R, C100ED-R manual Celestial Coordinate System

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Up to this point, this manual covered the assembly and basic operation of your telescope. However, to understand your telescope more thoroughly, you need to know a little about the night sky. This section deals with observational astronomy in general and includes information on the night sky and polar alignment.

The Celestial Coordinate System

To help find objects in the sky, astronomers use a celestial coordinate system that is similar to our geographical coordinate system here on Earth. 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 of arc, and seconds of arc. Declination readings 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 toward the west.

Figure 5-1

The celestial sphere seen from the outside showing R.A. and DEC.

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Contents Advanced Series Advanced Series GT Introduction Care and Cleaning of the Optics Page Advanced GT Series Setting up the Tripod Attaching the Equatorial MountInstalling the Counterweight Bar Attaching the Center Leg BraceFor Non-GT Models Only Installing the CounterweightAttaching the Hand Control Holder Advanced GT Models Only Attaching the Telescope Tube to the Mount Installing the Finderscope Optical TubeInstalling the Eyepieces Balancing the Tube in R.AAdjusting the Mount Balancing the Telescope in DECAttaching the Declination Cable For GT Models Only Adjusting the Mount in AltitudeAdjusting the Mount in Azimuth Powering the Telescope Advanced GT Hand Control Hand Control Operation Double StarsAlignment Procedures Startup ProcedureAuto Align Auto Three-Star AlignRe-Alignment Quick-AlignLast Alignment Object Catalog Selecting an ObjectSlewing to an Object Finding PlanetsTour Mode Constellation TourDirection Buttons Rate ButtonSetup Procedures Identify Scope Setup Features Precise GoToObserving Tip Helpful Hint Utility Features Helpful Hint Advanced GT Image Orientation Calculating Magnification FocusingAligning the Finderscope Determining Field of View General Observing HintsCelestial Coordinate System Motion of the Stars Pointing at Polaris Finding the North Celestial Pole DefinitionDeclination Drift Method of Polar Alignment Observing the Moon Lunar Observing HintsObserving the Planets Observing the SunSolar Observing Hints Observing Deep Sky ObjectsSeeing Conditions TransparencyPage Piggyback Short Exposure Prime Focus Photography Reducing Vibration Terrestrial PhotographyMetering Auto Guiding Care and Cleaning of the Optics Page Page Appendix a Technical Specifications Appendix B Glossary of Terms Page Eclipsing or obscuring the brightness of the star Appendix C Longitudes Latitudes Georgia Minnesota Rhode Island Canada Appendix D RS-232 Connection Additional RS232 Commands Appendix E Maps of Time Zones Page Page Page Page Page Page Page Celestron TWO Year Warranty

C100ED-R, C80ED-R specifications

Celestron, a renowned name in the field of astronomy, has built a reputation for producing high-quality telescopes that are accessible to both amateur and professional astronomers alike. Among their impressive lineup are the Celestron C100ED-R and C80ED-R telescopes, both of which are crafted to enhance the observational experience through advanced optics and user-friendly features.

The Celestron C100ED-R, a 100mm refractor telescope, stands out for its premium extra-low dispersion (ED) glass, which delivers exceptional color correction and sharpness. This ED technology minimizes chromatic aberration, ensuring clearer and more colorful celestial images. The telescope boasts a focal length of 900mm, resulting in a focal ratio of f/9. This combination allows for high magnification capabilities while maintaining a wide field of view, perfect for observing both planetary details and deep-sky objects. The robust, yet lightweight design of the C100ED-R makes it highly portable, allowing for convenient stargazing sessions.

On the other hand, the C80ED-R is a 80mm refractor telescope that combines portability with performance. With its 600mm focal length and f/7.5 focal ratio, the C80ED-R is ideal for wide-field observations, making it easy to explore star clusters and large nebulae. Like its larger counterpart, the C80ED-R features ED glass, which prevents color distortion, allowing for clear and crisp images. The compact design is perfect for those who wish to travel or set up in tight spaces, ensuring that astronomy remains accessible.

Both telescopes are equipped with high-quality multi-coated optics that enhance light transmission, resulting in brighter images. Celestron's user-friendly mounting systems allow for smooth tracking of celestial objects, making it easier to follow objects as they move across the night sky. Additionally, these telescopes come with a variety of accessories, including premium eyepieces that enhance the viewing experience, and sturdy tripods that provide stable support during observations.

In summary, both the Celestron C100ED-R and C80ED-R offer exceptional features that cater to a variety of observing needs. With advanced ED optics, high-quality construction, and portability, they are ideal choices for aspiring astronomers looking to explore the wonders of the universe. Whether you're interested in planetary observation or deep-sky exploration, Celestron's C100ED-R and C80ED-R will not disappoint.
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