Celestron CPC Series Manual de instrucciones descargar pdf (Pagina 28)

Up to this point, this manual covered the assembly and basic operation of your CPC 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.

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 6-1

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

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Celestron CPC Series Manual de instrucciones Pagina 28