The Moon's Libration in Longitude

Analysis of Yakovkin's results on a possible free libration of the Moon in longitude shows that the motion found agrees in speed and phase with the forced term whose argument is twice the difference of longitude of the perigee and node. If it is interpreted as due to this term $\gamma\,=\,0.0002049\,\pm\,0.0000009$. If the motion is a free one $\gamma\,=\,0.0002098\,\pm\,0.0000022$ The results imply values of f close to 0.67 and therefore intermediate between the two groups of determinations made from the annual libration.