User manual ORION TELESCOPES & BINOCULARS 09233

[. . . ] INSTRUCTION MANUAL Orion Equatorial Mount ® #9233 With Hardwood Tripod Customer Support (800) 676-1343 E-mail: support@telescope. com Corporate Offices (831) 763-7000 Providing Exceptional Consumer Optical Products Since 1975 P. O. Box 1815, Santa Cruz, CA 95061 IN 100 Rev. A 0998 Counterweight shaft Counterweight lock knob Tripod leg attachment bolt Counterweight Retaining washer and knob Accessory tray bracket Accessory tray Tripod leg Leg lock bolt Figure 1. EQ Mount Parts Diagram Latitude scale Latitude lock knob Dec. [. . . ] Using the Equatorial Mount When you look at the night sky, you no doubt have noticed that the stars appear to move slowly from east to west over time. That apparent motion is caused by the Earth's rotation (from west to east). An equatorial mount is designed to compensate for that motion, allowing you to easily "track" the movement of astronomical objects, thereby keeping them from drifting out of the telescope's field of view while you're observing. This is accomplished by slowly rotating the telescope on its right ascension axis, using only the R. A. axis of the mount must be aligned with the Earth's rotational (polar) axis--a process called polar alignment. Approximate Polar Alignment For Northern Hemisphere observers, reasonable polar alignment is achieved by pointing the mount's R. A. It lies within 1° of the north celestial pole (NCP), which is an extension of the Earth's rotational axis out into space. Stars in the Northern Hemisphere appear to revolve around Polaris. 4. Balancing the Telescope Once the telescope is attached to the equatorial mount, the next step is to balance the telescope. Proper balance is required to insure smooth movement of the telescope on both axes of the equatorial mount. If you attach your telescope with a 1/4"-20 adapter, it may not be possible to balance the scope precisely with respect to the declination axis, because the telescope cannot be moved back and forth as it can when a tube ring is used. Some 1/4"20 adapters have a slot or more than one hole through which the threaded post can be set, allowing some limited adjustment of the telescope's position for balancing. 4 To find Polaris in the sky, look north and locate the pattern of the Big Dipper (Figure 3, page 7). The two stars at the end of the "bowl" of the Big Dipper point right to Polaris. If you do not have a clear view of Polaris from your observing site, you will not be able to accurately polar-align the telescope. Observers in the Southern Hemisphere aren't so fortunate to have a bright star so near the south celestial pole (SCP). The star Sigma Octantis lies about 1° from the SCP, but it is barely visible with the naked eye (magnitude 5. 5). For general visual observation, polar alignment is performed as follows: 1. Level the equatorial mount by adjusting the length of the three tripod legs. Loosen the latitude lock knob and tilt the mount head until the pointer on the latitude scale is set at the latitude of your observing site. If you don't know your latitude, consult a geographical atlas to find it. For example, if your latitude is 50° North, set the pointer to 50 (again, there are two 50s on the scale; set the pointer to the one for which the letters "R. A. " near the R. A. setting circle face upward, not downward). [. . . ] To point the telescope to the east or west, or in other directions, you rotate the telescope on its R. A. Depending on the altitude of the object you want to observe, the counterweight shaft will be oriented somewhere between vertical and horizontal. The key things to remember when pointing the telescope is that a) you only move it in R. A. and Dec. , not in azimuth or latitude (altitude), and b) the counterweight and shaft will not always appear as it does in Figure 1. [. . . ]