Observations of Syncom 2 and Syncom 3 during seven separate periods of free drift have been used in an attempt to find the effective potential at synchronous height. Although the accelerations are well determined near the two longitudes, 180° E and 300° E, where the observations are clustered, the poor distribution in longitude does not permit a satisfactory determination of individual coefficients. It would be particularly valuable to have observations in the region 0 to 40° E or around either of the two stable points near 70° E and 250° E. If there is or has been any significant population of dust particles in distant geocentric orbits, it is likely that a proportion will have been captured in the synchronous resonance, and will have accumulated near the stable positions. It is therefore suggested that it would be worth attempting to observe whether there are clouds of dust particles near the stable longitudes, and in the stable plane for synchronous height.
A New ω-Stable Plane