The first appearance of the new Moon has been used throughout history and is still used today to determine religious calendars.Many
methods for predicting the Moon's appearance have been proposed throughout history and new models are still being developed.All
these models have to be tested against observations to test their validity.To this end, ancient and modern astronomers have
collected ... [Show full abstract] observations of new and old crescent Moons.Here we present the results of 539 observations of the Moon made over
several years by many experienced observers in good weather conditions.In addition to determining whether or not the Moon
was seen, the times of its first and last appearance were also carefully recorded.The addition of the appearance time means
that even an easily visible Moon, recorded when it can barely be seen, may be compared with a visibility criterion.The observational
data base greatly expands on previously published reports.