What do you understand by gha , sha and first point of aries

1
FOLLOW

gha-it is angle at celestial pole contined between celestial meridain passing through greenwich and observer measured westerly.
sha-it is westerly anle at celestial pole measured between first point of aries and observer.
first point of aries-when ecliptic cross equinoctial from south to norrth it intersect equinoctial call first point of aries.