Latitude in Snyder (page 15): For the "normal" Mercator projection (on the ellipsoid) this function defines the spacing of the parallels: if the length of the equator on the projection is (units of length or pixels) then the distance, , of a parallel of latitude from the equator is The isometric latitude is closely related to the conformal latitude : The formulae in the previous sections give the auxiliary latitude in terms of the geodetic latitude. The expressions for the geocentric and parametric latitudes may be inverted directly but this is impossible in the four remaining cases: the rectifying, authalic, conformal,
International Latitude Observatory The data collected by the observatories over the years still has use to scientists, and has been applied to studies of polar motion, the physical properties of the Earth, climatology and satellite tracking and navigation. The final six observatories were located, in order of Longitude (E to W), in: International Latitude Observatory The International Latitude Observatories were a system of (originally) six observatories located near the parallel of 39° 08' north latitude. They were used to measure the variation in latitude that occurs as a result of the "wobble" of the Earth on its polar axis. The original six observatories