Extended Data Fig. 1: Comparison of the r and i band light curve of ZTF SLRN-2020 (shown as red and yellow circles respectively, as indicated) to visual light curves of Galactic and extragalactic red novae from the literature.

The light curves have been normalized to peak magnitude. For each comparison object, we indicate the photometric band of the archival light curve in the legend. The comparison objects include V1309 Sco8, OGLE-BLG-36017, V838 Mon51, M31-LRN-201552,53, AT 2019zhd54, NGC 3437-OT55, AT 2017jfs56 and AT 2018hso57. Error bars are shown at 1σ confidence and 5σ upper limits are shown as symbols with downward arrows.