Left: the UVOIR bolometric flux of SN 2013dy (open circles). The UV flux fractions determined by HST UV spectroscopy are represented by blue filled squares. The NIR flux fractions determined by RATIR NIR spectroscopy are represented by red filled triangles. The blue and red dashed lines represent the UV and NIR flux fractions of SN 2011fe (Pereira et al. 2013), respectively. Right: the same as the left-hand panel, but using bolometric luminosity instead. The UVOIR bolometric luminosity of SN 2013dy is shown as blue filled circles. Here the luminosity distance determined using the Tully–Fisher relation (13.7 ± 3.0 Mpc; Tully et al. 2009) is adopted. The blue curve represents the B-spline fit to the data. The grey area shows the 1σ range of the bolometric luminosities considering the uncertainties from the distance. The bolometric luminosity of SN 2011fe from Pereira et al. (2013) is overplotted (red curve).