Moon: Definitions

Alt:The altitude of the Moon above the horizon when the Moon is due north. This is the highest altitude the Moon will reach between rising and setting. (The altitude at the horizon is 0; the altitude at the point directly overhead is 90 degrees.)

Azm: Azimuth is the direction relative to true north, measured around the horizon. Imagine yourself facing true north, which is zero degrees in azimuth. As you turn toward the east the azimuth you are looking towards will increase, reaching 90 degrees at east. If you continue turning in the same direction you will face southeast (azimuth 135 degrees), south (azimuth 180 degrees), southwest (235 degrees), west (270 degrees), northwest (315 degrees) and finally back to north at 0 degrees again. If the moonrise azimuth is 119 degrees, this means the moonrise point will be 29 degrees south of east. Azimuth is not the same as compass direction, because magnetic compasses do not point to true north or south. In Cape Town, true north is at a compass bearing of 23 degrees.

Rise: The rising time is when the upper edge of the Moon rises above the horizon at sea level. This assumes a horizon view not blocked by buildings, hills, etc.

Set: The setting time is the moment when the upper edge of the Moon sinks below the horizon at sea level, assuming a horizon view not blocked by buildings, hills, etc.

SAST:South African Standard Time is 2 hours ahead of Universal Time.

Trans: The `transit' time is the moment when the Moon is due north. This changes through the year, and the average value is different for different cities in South Africa. Note that the lunar transit time averages 49 minutes later each day because of the Moon's eastward motion through the sky during the course of each lunar month.

UT: Universal Time is the mean solar time of the Greenwich meridian at 0° longitude. Universal Time replaced Greenwich Mean Time in 1928 and is the international basis of civil and scientific time.