We present a multi-instrument analysis of the rapidly oscillating Ap ( roAp ) star HD 42659 .
We have obtained B photometric data for this star and use these data , in conjunction with TESS observations , to analyse the high-frequency pulsation in detail .
We find a triplet which is split by the rotation frequency of the star ( \nu _ { rot } = 0.3756 d ^ { -1 } ; P _ { rot } = 2.66 d ) and present both distorted dipole and distorted quadrupole mode models .
We show that the pulsation frequency , 150.9898 d ^ { -1 } ( P _ { puls } = 9.54 min ) is greater than the acoustic cutoff frequency .
We utilise 27 high-resolution ( R \simeq 65 000 ) , high signal-to-noise ( \sim 120 ) spectra to provide new orbital parameters for this , the only known roAp star to be in a short period binary ( P _ { orb } = 93.266 d ) .
We find the system to be more eccentric than previously thought , with e = 0.317 , and suggest the companion is a mid-F to early-K star .
We find no significant trend in the average pulsation mode amplitude with time , as measured by TESS , implying that the companion does not have an affect on the pulsation in this roAp star .
We suggest further photometric observations of this star , and further studies to find more roAp stars in close binaries to characterise how binarity may affect the detection of roAp pulsations .