Lower panel: inferred values of α as a function of inverse wavelength. The value of α appears to depend slightly on wavelength. An indicative value of α = −0.49 is shown as a red horizontal line. Upper panel: inferred extinction curves at different times. The optical bands used in the study are indicated. The g band is affected by Hβ emission and the r band is affected by Hα emission. The extinction is seen to increase with time and the extinction curves are fairly flat, suggesting gray extinction.