Meade ETX-90 User Manual - Page 52

EQUATORIAL ALIGNMENT "locked" positions, use the Arrow keys to move the optical tube. North + Celestial Pole North tripod leg Figure 20: Example of Polar Alignment. Note that the face of the tilt-plate points north Note: For most astronomical observing requirements, approximate settings of the telescope's latitude and North-pointing tripod leg (Steps #5 and #6) are acceptable. Do not allow undue attention to precise equatorial mounting of the telescope to interfere with your enjoyment of the instrument. Using an Equatorially Mounted Telescope Once your telescope is equatorially mounted, the telescope motor drive will keep a celestial object in the telescope eyepiece's field of view. Caution: Do not move the tripod or adjust the latitude setting while observing or the mounting alignment will be lost. The telescope's motor drive disengages when the Horizontal and the Vertical lock levers are unlocked and re-engages when the levers are relocked. AutoStar Polar Alignment North + Celestial Pole Latitude control bar Easy Polar Alignment Two alignment stars are chosen by AutoStar based on the date, time and location. First, choose "Polar" from the "Setup: Telescope: Mount" menu. The rest of the procedure is identical to the Alt/Az Easy (Two-Star) Align, page 11. One-Star Polar Alignment Polar One-Star Alignment requires some knowledge of the night sky. AutoStar provides a database of bright stars and one star from this database is chosen by the observer for alignment. Polaris is chosen by AutoStar. First, choose "Polar" from the "Setup: Telescope: Mount" menu. The rest of the procedure is almost identical to the Alt/Az One Star Alt/Az Alignment, page 41, except that AutoStar prompts you to point the telescope at Polaris and center it in the telescope eyepiece. Two-Star Polar Alignment Polar Two-Star Alignment requires some knowledge of the night sky. AutoStar provides a database of bright stars and two stars from this database are chosen by the observer for alignment. First, choose "Polar" from the "Setup: Telescope: Mount" menu. The rest of the procedure is almost identical to the Alt/Az Two Star Alt/ Az Alignment, page 39. Locating the Celestial Pole To get basic bearings at an observing location, take note of where the Sun rises (East) and sets (West) each day. After the site is dark, face North by pointing your left shoulder toward where the Sun sets. To precisely point at the pole, find the North Star (Polaris) by using the Big Dipper as a guide (Fig. 22). Important Note: For almost all astronomical observing requirements, approximate settings of the telescope's latitude and Polar axis are acceptable. Do not allow undue attention to precise Polar Alignment of the telescope to interfere with your basic enjoyment of the instrument. 52 Figure 21: Example of Polar Alignment. Note that the face of the tilt-plate points north AutoStar provides three different (manual) methods for polar alignment: Easy, One-Star and Two-Star. Little Dipper Polaris Big Dipper Figure 22: Locating Polaris Cassiopeia