Evolution of the parameters L_h, R_h, T_h (middle), and the mass-loss rate Ṁ_h from the hot component (bottom; the upper and lower limits are denoted by “upper l.” and “lower l.”). The dotted and grey lines mark the beginning of the explosion (June 5.10 ± 3.3) and the maxima in the LC (June 30.0 ± 2.0, Oct. 8.5 ± 0.5). Filled and open symbols correspond to T_h from Eqs. (7) and (8). Data are listed in Table 5.