Meade Tripod LX600-ACF 14 inch User Manual - Page 24

AutoStar #497 OHbAsNerDvBiOngX The Global Positioning System The Global Positioning System (GPS) is comprised of 24 satellites orbiting the Earth that are constantly transmitting their precise position and time. The system provides highly accurate, worldwide positioning and navigation information for any number of applications. GPS receivers on the Earth acquire signals from three to twelve satellites to determine the precise latitude, longitude, and time of the receiver. (Accuracy of the receiver's position may be within 10 to 15 feet.) As AutoStar II uses latitude, longitude, and time information to calculate the positions of celestial objects, GPS is an important tool for aligning your LX600 ACF telescope. Detecting True Level To detect level of the base of the telescope, AutoStar II must calculate the tip and tilt of the telescope at three compass points and then compensate for it. Finding level involves the geometric calculations of a "plane". In order to define a plane, three positions are necessary. This is not unlike building a table: For a table to stand level and solid, it must have a minimum of three legs. AutoStar II makes gravitational measurements to make a precise determination of true level. Finding True North Locating True North is one of the most important ingredients in the alignment of a telescope. True North is the axis-the pole-which the Earth spins about and is a key reference for the motion of the Earth. As you look at the night sky, the stars seem to move; in fact, if you watched long enough or took a long timeexposure photograph, you'd realize that the stars seem to revolve around one point-the pole or True North. When AutoStar II knows where True North is and also knows the time, it can calculate the location of all the other objects in the sky. One traditional way to find True North is to locate the North Star, Polaris, which lies very close to True North. Another way to calculate True North is to use gyroscopes or accelerometers. The LX600 ACF determines True North by using a magnetic North sensor. The sensor locates magnetic North. Magnetic North is not True North, but a measurement of the magnetic lines of the Earth. Magnetic North may deviate several degrees from True North. But AutoStar II, using the observation site location determined by the GPS and magnetic North information, can calculate the position of True North. Some areas are subject to magnetic disturbances, and the magnetic field of the Earth changes slightly from year to year. AutoStar II allows you to adjust for discrepancies in the local magnetic field using the "Calibrate Sensors" option in the Telescope menu. See page 33 for more information. Calibrate Home After a precise polar alignment (drift alignment) you may want to calibrate the Home Sensors on your mount. This procedure sets the 90 degree declination position and the zero hour angle of the RA axis very accurately. When you perform future alignments, the system uses these positions to aid in a precise alignment. Parking the Scope Designed for a telescope that is not moved between observing sessions. Align the telescope one time, then use this function to park the telescope. Once parked, the screen prompts to turn off power. The advantage of parking is that you do not need to align the telescope the next time you turn on Autostar; it remembers your alignment. Tip: When waking their telescope, some users select a bright star from the Objects menu and perform a GoTo on that star. If the star is not in the exact center of the eyepiece, move the star to the center using the arrow keys and then hold ENTER down for more than two seconds. This activates the Enter to Sync function and fine tunes and improves the telescope's alignment. Important Note: When the "Park Scope" option is chosen and the display prompts you to turn off the telescope's power, Autostar II is unable to be returned to operation without turning the power off and then back on. Most users can use the default park position when parking their LX600. The default park position is identical to the home position; fork arms parallel to the ground plane and OTA pointing forward toward the celestial pole. However, if you are storing your telescope in a location where it cannot be stored in the home position, for example, such as an observatory with a top that slides back, just move your telescope to the position you want to store it. Choose "Park Position" from the Setup: Telescope menu. When "Park Position" displays, use the down arrow key to scroll through the choices. Select "Use Current" if your position is anything other than the Home Position. If you are using the Home Position, select "Use Default." StarLock Operation Your LX600 Telescope incorporates the advanced StarLock™ system that makes target acquisition and accurate autoguiding during exposures completely automatic. The StarLock system incorporates a narrow field 80mm f/5 optic and a super wideangle lens that automatically finds your target with high precision, locks on to a field star and automatically begins guiding. StarLock Menu: 24