🔍 Key Concepts

• Meridian passage vs prime vertical – what does “lower transit” describe about a star’s position relative to your meridian? • How a line of position (LOP) is oriented relative to the azimuth (Zn) of the observed body • The special orientations of LOPs for bodies on your meridian or on your prime vertical

💭 Think About

• When a star is at lower transit, where is it in relation to your local meridian – crossing it, or 90° from it? • If an LOP is always drawn perpendicular to the body’s azimuth, what azimuth would a star have at lower transit, and what does that do to the LOP’s direction? • Which of the answer choices describe LOPs that have a very specific orientation (east–west or north–south), and which choice says it’s just an ordinary LOP without special geometry?

✅ Before You Answer

• Confirm that lower transit refers to the body crossing your meridian below the pole, not to the prime vertical • Work out the azimuth of a star when it is exactly on your meridian (upper or lower transit) and remember that the LOP is at right angles to that azimuth • Decide whether a meridian-related LOP will align more like a parallel of latitude (east–west) or a meridian of longitude (north–south)