New measurements of the mean magnetic field of the sun and its rotation

A list of 152 new measurements of the mean magnetic field (MMF) of the Sun as a star obtained at the Crimean Astrophysical Observatory (CAO) in 1991-1 997 are presented. They increase the total number of CAO MMF measurements t o N = 1549 (since 1968). This time series is studied together with similar data from the Mount Wilson Observatory (1970-1982, N = 2457). A (synodic) p eriod P-R = 26.95 +/- 0.06 days dominates in the power spectrum of the merg ed data for 1968-1997, revealing remarkable phase coherence over 30 years. This stability of the rotation of the "magnetic" Sun independent of the Ii- year cycle is difficult to explain in the framework of current theories for the generation of the global solar magnetic field that gives rise to the s olar cycle. There are two other periods in the solar MMF (approximate to 16 1 days and 1.0 year), whose origin is not yet clear.