  The number of known variable stars has increased by several magnitudes over
the last decade, and automated classification routines are becoming
increasingly important to cope with this development. Here we show that the
"upside-down CBH variables", which were proposed as a potentially new class of
variable stars by Heinze et al. (2018) in the ATLAS First Catalogue of Variable
Stars, are, at least to a high percentage, made up of alpha2 Canum Venaticorum
(ACV) variables - that is, photometrically variable magnetic chemically
peculiar (CP2/He-peculiar) stars - with distinct double-wave light curves.
Using suitable selection criteria, we identified 264 candidate ACV variables in
the ATLAS variable star catalogue. 62 of these objects were spectroscopically
confirmed with spectra from the Large Sky Area Multi-Object Fiber Spectroscopic
Telescope (all new discoveries except for nine stars) and classified on the MK
system. The other 202 stars are here presented as ACV star candidates that
require spectroscopic confirmation. The vast majority of our sample of stars
are main-sequence objects. Derived masses range from 1.4M(Sun) to 5M(Sun), with
half our sample stars being situated in the range from 2 M(Sun) to 2.4 M(Sun),
in good agreement with the spectral classifications. Most stars belong to the
thin or thick disk; four objects, however, classify as members of the halo
population. With a peak magnitude distribution at around 14th magnitude, the
here presented stars are situated at the faint end of the known Galactic mCP
star population. Our study highlights the need to consider rare variability
classes, like ACV variables, in automated classification routines.
