The low energy photoionization spectrum of propyne (CH3-CCH), which reveals the vibronic structure of the propyne cation, is simulated using vibronic coupling theory. The spin-orbit interaction is included using an intensity borrowing approach, enabling determination of the ((X) over tilde E-2(1/2/3/upsilon) nu=0) splitting and the relative photoionization intensity of these closely spaced levels. The results are compared with recent experimental studies and misstatements are corrected.