In one framework, lines along which this quantity is constant are specified by an equation containing the inverse of the Gudermannian. The “rectifying” and “authalic” forms of this quantity are two of the six “auxiliary” types of this quantity. W·G·S84 defines two radii, a and b, that appear in the function relating this quantity to geocentric radius. An observer's value of this quantity is one of the two quantities that determine whether an object is (*) circumpolar. This quantity can be determined by the positions of the stars, unlike a different quantity (10[1])that requires a chronometer (10[2])to estimate (10[1])using dead (10[1])reckoning. This geodetic (10[1])quantity is analogous (10[1])to the declination of the celestial sphere. The angle of the gnomon of a (-5[1])sundial equals this quantity. For 10 points, name this coordinate that indicates how far north or south of the equator a point on Earth is. (10[1])■END■