2102-D Star Finder plastic plates, 12" diameter, in sturdy case $39.00   ...item# 1841

2102-D Star Finder

The unit consists of a base plate (North Hemisphere on one side, South on the other), plus set of latitude plates. Use the Nautical Almanac to look up the GHA of Aries for the time of interest, then set the appropriate latitude disk on the base plate. Rotate the arrow on the latitude disk to the Local Hour Angle of Aries, and you have in your hand a complete (quantitative) picture of sky around you. From the disk you can read numerical locations of stars and planets, sun and moon — for example, the star Antares bearing 187° true and 25° above the horizon. This is an invaluable device for celestial navigators, but also useful for more general star gazing. See related discussion under The Star Finder Book, which describes in detail how to use this versatile device. Note that all you need from the almanac is the GHA of Aries, and this can be obtained from a simple long-term almanac (a short list of numbers); the annual purchase of a Nautical Almanac is not requried. Early editions of Bowditch, vol.II, contain such an almanac.