Star Finder: p. 2

The star finder consists of a circular star map

which can rotate (like the celestial sphere it represents) in a holder which has a "window" showing the portion of the star map that is above our horizon at a particular time. The rotatable star map is a polar map similar to the SC002. However since this star map must be able to show any star that might be above the horizon at CSB/SJU during the year, it covers a much larger part of the celestial sphere (85%, down to declination -45°) than does the SC002. Larger coverage means more distortion -- don't trust the shape of constellations displayed by the star finder near the edge of the star map's circle.