Almanac software computes celestial bodies' equatorial coordinates, their rise, set, and meridian transit times. It also determines the moments of twilight.
One of the key features of Almanac is the use of formulae that assume an ideal horizon, where the intersection of the sky with the apparent plane of the earth's surface is the horizon. In rise/set calculations, the software assumes that the observer has zero elevation, so the horizon is exactly 90 degrees from the local vertical. Almanac compensates for the refraction of light passing through the earth's atmosphere, which tends to make celestial bodies appear higher in the sky than they actually are. This effect becomes more pronounced as the altitude of the object decreases.
The software assumes average atmospheric conditions in accounting for refraction. Lunar parallax is another factor that affects the perceived altitude of the moon, as the observer is not at the center of the earth. This effect causes the moon to appear lower in the sky than it actually is. Almanac compensates for this parallax effect. However, the parallax for the Sun and planets is small enough to be ignored in this application.
Overall, Almanac is a reliable and accurate tool for anyone interested in tracking celestial bodies or predicting the times of twilight. Its user-friendly interface and advanced calculations make it a must-have for astronomers, photographers, and anyone interested in the night sky.
Version 1.0: N/A