What term describes the moments when a celestial object reaches the observer's meridian?

The term that describes the moments when a celestial object reaches the observer's meridian is culmination. This occurs when the object is at its highest point in the sky relative to an observer at a specific location. At this point, the celestial object is aligned with the observer's meridian, meaning it has reached its peak altitude above the horizon for that observer.

Understanding culmination is important in fields such as astronomy and navigation, as it helps in determining the best times for observation and accurate positioning. The maximum altitude achieved when a celestial object culminates is essential for calculations involving the position of celestial bodies and is particularly useful in celestial navigation.