Comparison of the −2 d PS1-12bwh spectrum to two pre-maximum epochs of SN 2005hk. The spectrum of PS1-12bwh has been binned to Δλ = 5 Å and the narrow host emission lines have been removed. All spectra were normalised by the average continuum flux. The gap in the PS1-12bwh spectrum around 5200 Å is due to the dichroic used. The lower panels show the residuals resulting from taking the difference between the spectra in the respective upper panel, confirming that the −2 d PS1-12bwh spectrum is a better spectroscopic match for the −12 d SN 2005hk spectrum, than the similarly phased −3 d spectrum. Features of interest are indicated by full vertical lines. The original data sources for spectra of SN 2005hk are given in Table A.3.