SkyMapper colours of Seyfert galaxies and Changing-Look AGN
  We study the utility of broad-band colours in the SkyMapper Southern Survey
for selecting Seyfert galaxies at low luminosity. We find that the $u-v$ index,
built from the ultraviolet $u$ and violet $v$ filters, separates normal
galaxies, starburst galaxies and type-1 AGN. This $u-v$ index is not sensitive
to age or metallicity in a stellar population but is instead a
quenching-and-bursting indicator in galaxies and detects power-law continua in
type-1 AGN. Using over 25,000 galaxies at $z<0.1$ from 6dFGS, we find a
selection cut based on $u-v$ and central $u$ band brightness that identifies
type-1 AGN. By eyeballing 6dFGS spectra we classify new Seyfert galaxies of
type 1 to 1.8. Our sample includes eight known Changing-Look AGN, two of which
show such strong variability that they move across the selection cut during the
five years of SkyMapper observations in DR3, along mixing sequences of nuclear
and host galaxy light. We identify 46 Changing-Look AGN candidates in our
sample, one of which has been reported as a type-IIn supernova. We show that
this transient persists for at least five years and marks a flare in a
Seyfert-1 period of a new Changing-Look AGN.
