We obtained thirteen spectropolarimetric observations of the strongly magnetic rapidly oscillating Ap star HD 154708 over three months with the multi-mode instrument FORS 1 , installed at the 8-m Kueyen telescope of the VLT .
These observations have been used for the determination of the rotation period of P = 5.3666 \pm 0.0007 d. Using stellar fundamental parameters and the longitudinal magnetic field phase curve , we briefly discuss the magnetic field geometry .
The star is observed nearly pole-on and the magnetic field geometry can be described by a centred dipole with a surface polar magnetic field strength B _ { d } between 26.1 and 28.8 kG and an inclination of the magnetic axis to the rotation axis in the range 22.5 ^ { \circ } to 35.5 ^ { \circ } .