Moonwatch -- July 14, 1988

The Moonwatch program using amateur astronomers to obtain a wide range of naked-eye sightings of the new moon to test a mathematical model for predicting first visibilty of the new moon is discussed. The algorithm takes physical effects such as brightness of the twilight sky, clarity of the atmosphere at the observing site, and the physiology of the human eye into account. A 1987 test of visibility prediction obtained poor results due to weather conditions. Observers across North and Central America, the Caribbean, and northern South America are asked to record information about the time and location where they first see the crescent of the new moon appear on the horizon.