Published online by Cambridge University Press: 14 August 2015
Doppler observations of Navy Navigation Satellites have been used to compute pole positions on a daily basis since 1969. Limited results exist for the period 1964 to 1969. Based on Doppler observations from four or five satellites, the standard error for a five-day mean pole position is less than 20 cm. Comparisons are made between BIH, IPMS and ILS results and those obtained from Doppler. It is shown that the six years of reliable Doppler data since 1972 contribute little in finding the Chandler period. Using observations from the three astronomical sources over 12 years yields a Chandler period of 432.0 ± 0.2 days.