Question 1565Navigation General

The correct answer is D) All of the above. Sidereal hour angle (SHA) is always: 1) Subtracted from the local hour angle (LHA) of the star to obtain the LHA of Aries, which is the reference point on the celestial sphere. 2) Measured westward from the hour circle containing the first point of Aries, which is the origin of right ascension. 3) Measured from the point on the celestial sphere occupied by the Sun at the vernal equinox, which defines the first point of Aries. All three statements accurately describe the definition and use of sidereal hour angle in celestial navigation, which is an important topic covered in US Coast Guard Captain's License Examinations.