Secular variability of the longitudinal magnetic field of the Ap star γ Equ

We present an analysis of the secular variability of the longitudinal magnetic field B _e in the roAp star γ Equ (HD 201601). Measurements of the stellar magnetic field B _e were mostly compiled from the literature, and we appended also our 33 new B _e measurements which were obtained with the 1-m optical telescope of the Special Astrophysical Observatory (Russia). All the available data cover the time period of 58 yr, and include both phases of the maximum and minimum B _e. We determined that the period of the long-term magnetic B _e variations equals  91.1 ± 3.6 yr  , with   B _e(max) =+577 ± 31 G  and   B _e(min) =−1101 ± 31 G  .