Summer and winter are poor seasons for galaxies other than our Milky Way, but by September the visually greatest external galaxy
, M31, is high enough for good evening views.
The brightest external galaxy
to be found in Cetus is Messier 77--the only Messier object in the constellation.
This is the sharpest visible-light image ever made of the nucleus of an external galaxy
M31 is the easiest external galaxy
to observe, and the view will only get better as Andromeda and the Milky Way move toward a collision and merger in about 4 billion years.
The ongoing starburst not only makes M82 the brightest external galaxy
in infrared light, it's been a major factor in shaping it into the highly disturbed object we see today.
Fesen (University of Colorado) and colleagues have recovered the visible remains of S Andromedae, the first supernova ever recorded in an external galaxy
I have not seen ordinary stars in an external galaxy
before or since.