Phase angle dependence of P_{cont, r} (panel a) and P_{gas, r} (panel b). In panel a, the thick solid line shows the trend of the 2P continuum component weighted by the data errors. The solid and dashed lines denote the average trends of high- and low-P_max comets, respectively. The filled symbols denote the data used in fitting, and open symbols are the excluded ones. The solid curve in panel b denotes the empirical phase function of fluorescence lines (Öhman 1941). The molecules analyzed in this study are expressed as stars. The meanings of the different symbols are given in the legend at the top left panel. Open stars of C₂ bands and of CN(3,1) are enlarged to avoid mutual overlapping.