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ASTRONOMY BASICS. Celestron 21038 Travel Scope 50, 21035 Travel Scope 70
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Celestron 21035 Travel Scope 70: With its top-quality materials and simple setup, this compact and portable telescope offers both terrestrial and casual astronomical observation capabilities. Featuring coated glass optics for clear images, an erect image diagonal for correctly oriented views, and a smooth functioning altazimuth mount for easy pointing, this telescope is ideal for beginners. Explore the wonders of the night sky or observe distant objects during the day with ease.
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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.
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 wes t.
Figure 4-1
The celestial sphere seen from the outside showing R.A. and DEC.
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Table of contents
- 3 INTRODUCTION
- 5 ASSEMBLY
- 5 Setting up the Tripod
- 6 Attaching the Telescope Optical Tube to the Tripod
- 6 Moving the Travel Scope Manually
- 7 Installing the Diagonal & Eyepiece
- 7 Installing the Finderscope – Travel Scope 70 only
- 7 Aligning the Finderscope
- 8 TELESCOPE BASICS
- 8 Focusing
- 8 Calculating Magnification
- 8 Installing & Using the Barlow Lens
- 9 Determining Field of View
- 9 General Observing Hints
- 10 ASTRONOMY BASICS
- 10 The Celestial Coordinate System
- 11 Motion of the Stars
- 12 CELESTIAL OBSERVING
- 12 Observing the Moon
- 12 Observing the Planets
- 12 Observing the Sun
- 13 Observing Deep-Sky Objects
- 15 Seeing Conditions
- 16 TELESCOPE MAINTENANCE
- 16 Care and Cleaning of the Optics
- 17 TECHNICAL SPECIFICATIONS