Measurement of the solar rotation, 1978, from recurrent and non-recurrent sunspots

Results are presented for the solar rotation, 1978, as derived from sunspots by two different methods. Using recurrent spots only, the latitude dependence of the sidereal rotation rate was calculated to be =(14.41±0.05)–(3.13±0.26) sin² . Using recognizable spots, both recurrent and non-recurrent, average rotation rates were obtained for 5-degree intervals of latitude. The results from these two approaches were found to be in agreement with observations made between 1878 and 1951, suggesting that the solar rotation has not changed in the past 100 years.Currently at Northwestern University, Evanston, Ill., U.S.A.