Up to this point, this manual covered the assembly and basic operation of your NexStar 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 6-1

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

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Celestron 93507 manual Celestial Coordinate System, Celestial sphere seen from the outside showing R.A. and DEC
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93507 specifications

The Celestron 93507 is a powerful and versatile telescope designed for both amateur and seasoned astronomers. This model combines advanced technologies and practical features to deliver an enriching stargazing experience. One of the standout characteristics of the Celestron 93507 is its robust optical design. It features a 90mm aperture, allowing users to capture bright, detailed views of celestial objects, from the lunar surface to distant galaxies. The telescope employs a Maksutov-Cassegrain optical design, known for its compact form factor and high-quality images, free from chromatic aberration.

In terms of usability, the Celestron 93507 is designed with an easy setup in mind. It comes equipped with a solid mount that provides stability during observation. The mount also includes slow-motion controls, facilitating smooth panning across the night sky, allowing astronomers to track celestial objects effortlessly. This feature is particularly beneficial for viewing planets and other fast-moving astronomical phenomena.

Furthermore, the telescope comes with high-grade optics, including fully coated glass elements that enhance light transmission and ensure sharper images with higher contrast. It includes two eyepieces — a low-power 25mm and a high-power 10mm — that provide versatility in viewing options, whether you’re looking at wide expanses of the night sky or zooming in on close details of lunar craters.

Additionally, the Celestron 93507 is compatible with various Celestron accessories, including solar filters and advanced eyepieces, enabling users to expand their observational capabilities. The telescope's compact design makes it portable, perfect for amateur astronomers who enjoy taking their telescope for trips to dark-sky locations.

Another noteworthy feature of this telescope is its durability. Built to withstand the rigors of outdoor usage, the materials used in the Celestron 93507 are resistant to wear and tear, ensuring that users can enjoy stargazing for years.

Overall, the Celestron 93507 is a well-rounded instrument that combines advanced optical technology, user-friendly features, and portability, making it an excellent choice for anyone looking to explore the wonders of the universe. Whether you're interested in planetary observation, lunar details, or deep-sky wonders, this telescope offers the tools necessary to make your astronomical explorations rewarding.
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