Ground-based optical photometry of the 2014 eruption of M31N 2008-12a, all data are taken from Table 6. Epochs of optical spectra from the 2014 eruption (black lines), 2012 eruption (grey line), and the SSS behaviour (blue lines) are shown for informational purposes. Top panel: optical light curve; the dotted lines indicate a template light curve based on the V- (green) and R/r′-band (red) observations of the 2008, 2011, 2012, and 2013 eruptions, and we assume t_max = 56 933.7 (MJD) or 2014 Oct. 3.7 UT (see discussion in Sect. 4.1 and DWB14). Bottom panel: colour evolution of the 2014 eruption of M31N 2008-12a.