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 gamma 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.