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In this study, we present observations of a type Iax supernova, PS1-12bwh,discovered during the Pan-STARRS1 3$\pi$-survey. Our analysis was driven bypreviously unseen pre-maximum, spectroscopic heterogeneity. While the lightcurve and post-maximum spectra of PS1-12bwh are virtually identical to those ofthe well-studied type Iax supernova, SN 2005hk, the $-$2 day spectrum ofPS1-12bwh does not resemble SN 2005hk at a comparable epoch; instead, we foundit to match a spectrum of SN 2005hk taken over a week earlier ($-$12 day). Weare able to rule out the cause as being incorrect phasing, and argue that it isnot consistent with orientation effects predicted by existing explosionsimulations. To investigate the potential source of this difference, weperformed radiative transfer modelling of both supernovae. We found that thepre-maximum spectrum of PS1-12bwh is well matched by a synthetic spectrumgenerated from a model with a lower density in the high velocity ($\gtrsim$6000km~s$^{-1}$) ejecta than SN 2005hk. The observed differences between SN 2005hkand PS1-12bwh may therefore be attributed primarily to differences in the highvelocity ejecta alone, while comparable densities for the lower velocity ejectawould explain the nearly identical post-maximum spectra. These two supernovaefurther highlight the diversity within the SNe Iax class, as well as thechallenges in spectroscopically identifying and phasing these objects,especially at early epochs.

Growing evidence that SNe Iax are not a one-parameter family: the case of PS1-12bwh