The angle measured westwards from the observer's meridian is an example of which astronomical measurement?

The angle measured westwards from the observer's meridian is indeed referred to as the Local Hour Angle (LHA). This measurement is used in celestial navigation and astronomy to indicate the position of a celestial object relative to an observer's local meridian. Specifically, LHA is the measure of time since the celestial object last crossed the observer's meridian, expressed in degrees. Since the Earth rotates 360 degrees in approximately 24 hours, each hour corresponds to 15 degrees; as such, an angle of 15 degrees west corresponds to one hour of time.

In practical applications, LHA helps determine when a celestial object will be highest in the sky (culmination) for a given observer. This makes LHA particularly useful in locating stars and other celestial bodies.

The other choices, while all important in astronomy, do not correctly describe an angle measured westwards from the observer's meridian. Local Sidereal Time, for example, relates to the position of the Earth in its rotation relative to distant stars but does not specifically denote an angle. Right Ascension is a coordinate used in celestial navigation similar to longitude, but it is defined with respect to the celestial equator rather than an observer's local meridian. Solar Declination is a