User manual CELESTRON ZOOM MASTER II

[. . . ] The NexStar-i is fully upgradeable and can be equipped with the optional NexStar Hand Control with a database of over 40, 000 objects (see the Computerized Hand Control section of this manual) for fully automated operation. Some of the many standard features of the NexStar include: · · · · Incredible 6°/second (or faster) slew speed. Expandability to add smart accessories such as Computerized Hand Control and GPS capabilities. Many other high performance features!The NexStar's deluxe features combine with Celestron's legendary Schmidt-Cassegrain optical system to give amateur astronomers one of the most versatile and easy to use telescopes available on the market today. [. . . ] If you turn the focus knob too quickly, you can go right through focus without seeing the image. To avoid this problem, your first astronomical target should be a bright object (like the Moon or a planet) so that the image is visible even when out of focus. Critical focusing is best accomplished when the focusing knob is turned in such a manner that the mirror moves against the pull of gravity. For astronomical observing, both visually and photographically, this is done by turning the focus knob counterclockwise. Figure 6-3 The emblem on the end of the focus knob shows the correct rotational direction for focusing the NexStar. Calculating Magnification You can change the power of your telescope just by changing the eyepiece (ocular). To determine the magnification of your telescope, simply divide the focal length of the telescope by the focal length of the eyepiece used. In equation format, the formula looks like this: Focal Length of Telescope (mm) Magnification = Focal Length of Eyepiece (mm) Let's say, for example, you are using the 25mm Plossl eyepiece. To determine the magnification you simply divide the focal length of your telescope (the NexStar 8i has a focal length of about 2000mm) by the focal length of the eyepiece, 25mm. Although the power is variable, each instrument under average skies has a limit to the highest useful magnification. The general rule is that 60 power can be used for every inch of aperture. Multiplying 8 by 60 gives a maximum useful magnification of 480 power. Although this is the maximum useful magnification, most observing is done in the range of 20 to 35 power for every inch of aperture which is 160 to 280 times for the NexStar 8 telescope. Determining Field of View Determining the field of view is important if you want to get an idea of the angular size of the object you are observing. 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. 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. Since the Earth rotates once every 24 hours, there are 24 lines total. 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 7-1 The celestial sphere seen from the outside showing R. A. and DEC. 36 Motion of the Stars The daily motion of the Sun across the sky is familiar to even the most casual observer. This daily trek is not the Sun moving as early astronomers thought, but the result of the Earth's rotation. [. . . ] The last two characters will always be zero. The cable required to interface to the telescope has an RS-232 male plug at one end and a 4-4 telephone jack at the other end. The wiring is as follows: 65 APPENDIX E ­ MAPS OF TIME ZONES 66 67 68 69 70 71 72 73 CELESTRON ONE YEAR WARRANTY A. Celestron warrants this telescope to be free from defects in materials and workmanship for one year. Celestron will repair or replace such product or part thereof which, upon inspection by Celestron, is found to be defective in materials or workmanship. [. . . ]