User manual MEADE LX90-LNT

[. . . ] Instruction Manual 8" LX90 Schmidt-Cassegrain Telescope AutoStar® -- LNTTM -- SmartFinderTM The Meade Schmidt-Cassegrain Optical System (2) (1) Ray (2) Ray (1) (2) (1) Focal Plane Secondary Mirror Primary Baffle Tube Field Stops Primary Mirror Correcting Plate Secondary Baffle (1) (2) In the Schmidt-Cassegrain design of the Meade LX90, light enters from the right, passes through a thin lens with 2-sided aspheric correction ("correcting plate"), proceeds to a spherical primary mirror, and then to a convex secondary mirror. The convex secondary mirror multiplies the effective focal length of the primary mirror and results in a focus at the focal plane, with light passing through a central perforation in the primary mirror. The Meade 8" LX90 Schmidt-Cassegrain includes an oversize primary mirror of an 8. 25" diameter, yielding a fully illuminated field-of-view significantly wider than is possible with a standard-size primary mirror. Note that light ray (2) in the figure would be lost entirely, except for the oversize primary. [. . . ] You will enter the object's name and RA and Dec coordinates (required information). You may also enter the object's magnitude and size (optional information). Although AutoStar contains an extensive database of celestial objects (stars, nebulae, planets, etc. ) that you can observe, you may eventually want to view objects that are not part of the database. AutoStar provides a feature that allows you to enter an object's R. A and Dec coordinates in the "User: Objects" option of the Object menu and allows automatic slewing of the telescope to the user-entered coordinates. In order to use this menu option, you first need to look up the R. A and Dec coordinates of the object or objects you wish to observe. Check out your local library, computer store, or bookstore for astronomy books, CD Roms, or magazines (such as Sky & Telescope or Astronomy), to find coordinates of celestial objects. The objects/coordinates you enter become part of your own permanent database, called "User Objects. " To enter coordinates of an object into the "User: Objects" option of the Object menu: 1. Make sure AutoStar has been initialized and the telescope has been aligned. After the telescope is aligned, "Select Item: Object" displays. (If necessary, use the Scroll keys to scroll through the menus, as previously described, to find this option. ) Press ENTER. Keep pressing the Scroll Up key until "Object: User Object" displays and press ENTER. "Name" displays on the top line and a blinking cursor on the second line. Use the Arrow keys, as previously described, to enter the name of the object you wish to add to the database. Use the Number keys to enter the digits for the Right Ascension coordinate of your object. Use the Number keys to enter the digits for the Declination coordinate of your object. If necessary, use the Scroll Keys to change "+" to "-. " When you are finished, press ENTER. Use the Number keys to enter the size (in arc-minutes), if so desired, and press ENTER to go to the next display. If you do not wish to enter this information, simply press ENTER. 3. 7. 8. 31 9. AutoStar then prompts you to enter the magnitude of the object. Use the Number keys to enter this information, if so desired, and press ENTER to go to the next display. "User Object: Add" displays again. To GO TO a user-entered object: In this procedure, you will choose an object from the User Object list and GO TO the object. With "User Object: Add" displayed, press the Scroll Up key once. [. . . ] The major division in Saturn's rings, called the Cassini Division, is occasionally visible through the LX90. Titan, the largest of Saturn's 18 moons can also be seen as a bright, star-like object near the planet. Deep-Sky Objects Star charts can be used to locate constellations, individual stars and deep-sky objects. Examples of various deep-sky objects are given below: Stars are large gaseous objects that are self-illuminated by nuclear fusion in their core. [. . . ]