An auxiliary latitude also called the reduced latitude and denoted or . It gives the latitude on
a sphere of radius for which the parallel has the same radius as the parallel
of geodetic latitude and the ellipsoid through
a given point. It is given by
Adams, O. S. "Latitude Developments Connected with Geodesy and Cartography with Tables, Including a Table for Lambert Equal-Area
Meridional Projections." Spec. Pub. No. 67. U. S. Coast and Geodetic Survey,
1921.Snyder, J. P. Map
Projections--A Working Manual. U. S. Geological Survey Professional
Paper 1395. Washington, DC: U. S. Government Printing Office, p. 18, 1987.