The sky density distribution of all transient candidates from each predicted class, with the total classified number indicated in the title. The location of the Cas A remnant is shown in the bottom left panel, together with other Galactic transients where scattered light echoes have been reported (Eta Carinae and Tycho’s remnant). The white circular gaps correspond to regions at high ecliptic latitude (∣β∣ > 80^∘) with incomplete image coverage, which were excluded from the search.