Exponential models of the radio flare 2009A. Top panel: black squares indicate measurements at 37 GHz, the blue circles indicate 15 GHz data, after continuum subtraction. The red solid line is the exponential model of Eq. (1), and describes the 37 GHz flare, while the red dashed vertical line indicates the event peak. The green solid line models the 15 GHz flare, and the green dashed vertical line indicates the flare peak. Bottom panel: residuals of the data after the subtraction of the exponential model. Colors are as in the top panel.