Light curve of SN Ia 2007sr in NGC 4038 in B (blue), V (green), and I (red) from different sources. The full lines are the light curves of SN 2011fe (Fig. 2) which has closely the same decline rate of Δm₁₅ = 1.10; the poorly fitting tail of the B light curve is shown as a dashed line. The maximum epochs and those 15 and 35 days after B maximum are marked. The light curves in V and I are shifted by  − 1 and  − 2mag, respectively.