Top: two example SEDs and the best-fit reddened blackbody function. The K_s photometry is shown for the t = 80.4 d epoch, although is not included in the fitting. Bottom: temperature evolution of AT 2019abn, as derived from SED fitting of the optical-NIR photometry and assuming E_B − V = 0.85. B-band was used in the fitting when available. All BVr′i′z′H epochs shown in the plot were also fitted using Vr′i′z′H, which agreed well. For clarity we therefore only show the Vr′i′z′H fits at epochs with no B-band. The filters included in the fitting of each point are shown in the legend. The dashed lines illustrate the evolution for E_B − V = 0.90 (upper) and E_B − V = 0.79 (lower).