Definition:Observer's Meridian

Definition

Consider the celestial sphere whose observer is $O$.

Let $P$ and $Q$ be the north celestial pole and south celestial pole respectively.

Let $Z$ be the zenith.

Let $S$ be the south point of the horizon.

The observer's meridian is the semi-great circle $PZSQ$.

Sources

• 1976: W.M. Smart: Textbook on Spherical Astronomy (6th ed.) ... (previous) ... (next): Chapter $\text {II}$. The Celestial Sphere: $19$. Declination and hour angle.