An Unusual Transient in the Extremely Metal-Poor Galaxy SDSS
  J094332.35+332657.6 (Leoncino Dwarf)
  We have serendipitously discovered that Leoncino Dwarf, an ultra-faint,
low-metallicity record-holder dwarf galaxy, may have hosted a transient source,
and possibly exhibited a change in morphology, a shift in the center of
brightness, and peak variability of the main (host) source in images taken
approximately 40 yr apart; it is highly likely that these phenomena are
related. Scenarios involving a Solar System object, a stellar cluster, dust
enshrouding, and accretion variability have been considered, and discarded, as
the origin of the transient. Although a combination of time-varying strong and
weak lensing effects, induced by an intermediate mass black hole (10$^4$ - 5
$\times$ 10$^{5}$ M$_{\odot}$) moving within the Milky Way halo (0.1 -- 4 kpc),
can conceivably explain all of the observed variable galaxy properties, it is
statistically highly unlikely according to current theoretical predictions,
and, therefore, also discarded. A cataclysmic event such as a
supernova/hypernova could have occurred, as long as the event was observed
towards the later/late-stage descent of the light curve, but this scenario
fails to explain the absence of a post-explosion source and/or host HII region
in recent optical images. An episode related to the giant eruption of a
luminous blue variable star, a stellar merger or a nova, observed at, or near,
peak magnitude may explain the transient source and possibly the change in
morphology/center of brightness, but can not justify the main source peak
variability, unless stellar variability is evoked.
