Celestron CGEM DX 1400 HD Computerized Telescope CGEM DX Mount Manual - Page 22

the celestial pole, you can simply point the polar axis of your telescope at Polaris. Although this is by no means perfect alignment, it does get you within one degree and is suitable for visual observing and short exposure piggyback photography. This must be done in the dark when Polaris is visible and can be done using the hole in the polar axis or with the help of the optional polar axis finderscope. See Optional Accessory section. 1. Set the telescope up so that the polar axis is pointing towards north (see figure 4-4). 2. Remove the polar finderscope cover and the polar axis cover from both sides of the mount. The polar finderscope cover unthreads from the rear of the mount and the polar axis cover simply press fits into the front of the mount. See figure 4-4. 3. Loosen the DEC clutch knob and move the telescope so that the tube is perpendicular to the polar axis, ie, the tube should be pointing either due west or east. 4. Look through the hole located underneath the polar finderscope cover (or through the eyepiece if using the optional polar axis finderscope). You should be able to see the sky from the hole under the polar axis cover. 5. Adjust the mount in altitude and/or azimuth until Polaris is visible through the polar axis hole. Center Polaris as accurately as possible. Like the previous method, this gets you close to the pole but not directly on it. For help in identifying and locating Polaris, read the section below. reside. For example, in the northern hemisphere all stars move around the north celestial pole. When the telescope's polar axis is pointed at the celestial pole, it is parallel to the Earth's rotational axis. Many methods of polar alignment require that you know how to find the celestial pole by identifying stars in the area. For those in the northern hemisphere, finding the celestial pole is not too difficult. Fortunately, we have a naked eye star less than a degree away. This star, Polaris, is the end star in the handle of the Little Dipper. Since the Little Dipper (technically called Ursa Minor) is not one of the brightest constellations in the sky, it may be difficult to locate from urban areas. If this is the case, use the two end stars in the bowl of the Big Dipper (the pointer stars). Draw an imaginary line through them toward the Little Dipper. They point to Polaris (see Figure 4-5). The position of the Big Dipper changes during the year and throughout the course of the night. When the Big Dipper is low in the sky Big Dipper Little Dipper N.C.P. Pointer Stars Polaris (North Star) Cassiopeia Polar Axis Cover NtooPrwothianrtdss Polar Finderscope Cover Figure 4-4 Finding the North Celestial Pole In each hemisphere, there is a point in the sky around which all the other stars appear to rotate. These points are called the celestial poles and are named for the hemisphere in which they Figure 4-5 The two stars in the front of the bowl of the Big Dipper point to Polaris which is less than one degree from the true (north) celestial pole. Cassiopeia, the "W" shaped constellation, is on the opposite side of the pole from the Big Dipper. The North Celestial Pole (N.C.P.) is marked by the "+" sign. (i.e., near the horizon), it may be difficult to locate. During these times, look for Cassiopeia (see Figure 4-5). Observers in the southern hemisphere are not as fortunate as those in the northern hemisphere. The stars around the south celestial pole are not nearly as bright as those around the north. The closest star that is relatively bright is Sigma Octantis. This star is just within naked eye limit (magnitude 4.5) and lies about 59 arc minutes from the pole. The north celestial pole is the point in the northern hemisphere around which all stars appear to rotate. The counterpart in the southern hemisphere is referred to as the south celestial pole. 20