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We present the analysis of K2 short cadence data of the rapidly oscillatingAp (roAp) star, 33 Librae (HD 137949). The precision afforded to the K2 dataallow us to identify at least 11 pulsation modes in this star, compared to thethree previously reported. Reoccurring separations between these modes leads usto suggest a large frequency separation, $\Delta\nu$, of 78.9 $\mu$Hz, twicethat reported in the literature. Other frequency separations we detect mayrepresent the small frequency separation, $\delta\nu$, but this is inconclusiveat this stage due to magnetic perturbation of the frequencies. Due to thehighly non-linear pulsation in 33 Lib, we identify harmonics to four times theprincipal frequency. Furthermore, we note a unique occurrence of non-linearinteractions of the 11 identified modes. The frequency separations of the modesaround the principal frequency are replicated around the first harmonic, withsome interaction with the second harmonic also. Such a phenomenon has not beenseen in roAp stars before. With revised stellar parameters, linearnon-adiabatic modelling of 33 Lib shows that the pulsations are not greaterthan the acoustic cutoff frequency, and that the $\kappa$-mechanism can excitethe observed modes. Our observations are consistent with 33 Lib having arotation period much larger than 88 d as presented in the literature.

K2 observations of the rapidly oscillating Ap star 33 Lib (HD 137949): new frequencies and unique non-linear interactions