Watts Angle (WA) and Axis Angle (AA)
Axis Angle - the angle of the event around the limb of the moon,measured eastward from the moon's north pole. Essential forreappearance, as it locates the event with reference to lunar features.To use, mark a map of the moon around the circumference at 10 degintervals, starting at the north pole. Mare Crisium is at about 300deg.
[Note - the so-called Watts Angle differs from the Axis Angle by 0.21deg. The term Watts Angle is limited to the context of accessing theWatts Charts. In all other situations, the term Axis Angle ispreferred.]
作者:
occult 時間: 2009-9-9 23:28
Cusp Angle (CA)
Cusp Angle - the angle of the event around the limb of the moon,measured from the nearest cusp. -'ve values indicate a bright limbevent. The cusps are usually N (north) or S (south), but near full mooncan be E (East) or W (west).
If a lunar eclipse is in progress, CA gives is the % distance from thecentre of the umbra, and is followed by a 'U'. Values up to 103% arepossible. Where an event occurs more than 103% of the umbral radius,the usual Cusp Angle value is displayed.