Spectro-photometry. The two upper panels show the variation in the spectral shape with respect to the 2.2 μm channel, the third panel shows the absolute flux in the latter, and the lower panel the visual flux in magnitudes. In each panel two cycles of the R52 model series are consecutively overplotted as the solid line. On the left, the cycles are shown as a function of visual phase while on the right they are phase-folded.