The NexStar computer hand control supplied with the Celestron CGEM telescopes is powered by the CGEM mount itself. No extra batteries or power supplies are needed. The

The NexStar computer has a built-in database of more than 40,000 stars and objects it can find and track for you. These include the complete RNGC, Messier, Caldwell, IC, and Abell catalogs; selected SAO stars; the planets, the Moon, and others. The custom database lists of all the most famous deep-sky objects by name and catalog number; the most beautiful double, triple and quadruple stars; selected variable stars; non-planetary solar system objects; and asterisms. You can also store and edit the right ascension and declination of 400 additional user-defined objects of your own choosing, such as the comet and asteroid coordinates published monthly in Astronomy and Sky & Telescope magazines. The computer control can find any of those objects with only a few keystrokes, and track them with high accuracy for visual or photographic applications. There is enhanced information on over 200 of the most note-worthy objects.

All of the database and mount operation information is displayed on a double line, 16-character, liquid crystal display on the NexStar hand control. There are 19 fiber optic backlit LED buttons to make it easy for you to control the NexStar computer without affecting your dark-adapted vision. An RS-232 communication port on the hand control allows you to operate your telescope remotely via a personal computer using the supplied RS-232 cable and NexRemote software CD-ROM.

The NexStar hand control provides a constant digital r. a. and dec readout of your scope's position on the sky. This provides much greater accuracy than conventional manual setting circles for star-hopping or locating objects by their celestial coordinates alone, should you want to observe the old-fashioned way without using the computer to find objects for you.

The software built into the CGEM NexStar hand control includes mount calibration, database filter limits, hibernate, five alignment procedures, user-defined slew limits, a new "All-Star" polar alignment routine that uses any bright star for a quick and accurate polar alignment, and more. Built-in adjustable backlash compensation permits precise corrections during astrophotography and when observing visually at high powers. A high precision pointing subroutine in the computer lets you point accurately at objects that you want to photograph that are too dim to be seen though the scope.

The software includes permanent programmable periodic error correction (PEC) to correct for the minor periodic tracking errors inherent to all worm drives that might otherwise mar your long exposure photographs. The NexStar computer retains the PEC corrections when it is powered down. The hand control and motor control software is flash-upgradeable to allow you to download the latest product updates over the Internet to keep your NexStar computer control always at the cutting edge of technology.

Five different alignment methods are built into the NexStar computer - 2-star align, quick align, 1-star align, last alignment, and solar system align - allowing you to choose a level of computer accuracy in automatically finding objects with which you are comfortable. Alignment is easily accomplished in only a few short minutes. You can be observing in less than 15 minutes after you first take your CGEM-mounted scope outdoors.

In addition, the NexStar computer hand control is GPS-compatible (using an optional inexpensive CN16 GPS module) for full GPS (Global Positioning System) satellite accuracy. Adding GPS to the computer is something no competitively-priced mount can do. Once the scope is approximately polar aligned, the 16-channel CN16 GPS system uses signals from government satellites to calculate the scope's location on earth with an accuracy measured in meters. The system also calculates the current time based on the split second accuracy of the GPS time signals. After the CN16 quickly completes these calculations and enters the information into the computer control for you automatically, the computer can then orient the scope with the sky, slew to a pair of guide stars, ask you to confirm that the stars are in the center of the field (and center them if they're not precisely aligned), and then start finding and tracking over 40,000 objects for you at your command. With the CGEM go-to mount and the CN16, orienting your scope in time and space on earth and aligning it on the sky becomes almost as easy a task as simply turning the mount on.