Verification of Earth's "Pear Shape" Gravitational Harmonic

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Science  23 Sep 1960:
Vol. 132, Issue 3430, pp. 807-808
DOI: 10.1126/science.132.3430.807


Predictions of the orbit of the Transit 1B satellite were systematically in error until account was taken of a third-order gravitational harmonic. The amplitude deduced for this harmonic by O'Keefe from the Vanguard I orbit serves very well, even though the orbits and the methods of observation and orbit fitting for the two satellites are quite different.