Formula used to determine the gravitational acceleration at a given latitude (g_φ‎) for a model of the Earth that comprises a rotating, oblate spheroid. g_φ‎= g₀(1 + α‎ sin² φ‎ + β‎ sin² φ‎), where g₀ is the value at the equator, of 978.0318 gals, φ‎ is the latitude, and the constants α‎ and β‎ are 0.0053024 and −0.0000058.