We undertook a time-series photometric multi-site campaign for the rapidly oscillating Ap star HD 99563 and also acquired mean light observations over two seasons .
The pulsations of the star , that show flatter light maxima than minima , can be described with a frequency quintuplet centred on 1557.653 \mu Hz and some first harmonics of these .
The amplitude of the pulsation is modulated with the rotation period of the star that we determine with 2.91179 \pm 0.00007 d from the analysis of the stellar pulsation spectrum and of the mean light data .
We break the distorted oscillation mode up into its pure spherical harmonic components and find it is dominated by the \ell = 1 pulsation , and also has a notable \ell = 3 contribution , with weak \ell = 0 and 2 components .
The geometrical configuration of the star allows one to see both pulsation poles for about the same amount of time ; HD 99563 is only the fourth roAp star for which both pulsation poles are seen and only the third where the distortion of the pulsation modes was modelled .
We point out that HD 99563 is very similar to the well-studied roAp star HR 3831 .
Finally , we note that the visual companion of HD 99563 is located in the \delta Scuti instability strip and may thus show pulsation .
We show that if the companion was physical , the roAp star would be a 2.03 M _ { \odot } object , seen at a rotational inclination of 44 \degr , which then predicts a magnetic obliquity \beta = 86.4 \degr .