It is always interesting to mull over the question of whether or not this, or
that, comet is indeed a 'Great Comet'. The actual justification for assigning
the title is rather more ambiguous than most think, as the meaning of this
appellation is less well defined than most believe.

Although most often used to designate some truly extraordinary, brilliant,
long-tailed comet, prior to about 1850 the name was occasionally applied simply
to some moderately bright comet that happened to appear in a given year. In
other instances some truly outstanding objects were initially widely known by
the name of their discoverer, only gaining the prefix 'Great Comet' after their
apparition ended. The name has also often been affixed to bright comets that
have appeared suddenly out of the twilight and were spotted by so many that no
specific first discoverer(s) could be determined and it was easier to do so.

However, the more accepted modern interpretation seems mainly to center around
comets of extreme brilliance and possessing long bright tails. Even so, any
critical determination is still dubious enough that various authors can differ
in their lists of 20th/21st century examples and particularly in their pecking
order.

From my own viewpoint I regard Comet Lovejoy as probably making the 'Great
Comet' cut, but only just barely. I would tend to group it along with the Great
Southern Comets of 1880 and 1887 as a marginal member of the clan. The two
earlier comets gained the title mostly by virtue of their impressive tails and
sudden appearance, as their heads were never seen as very bright in a reasonably
dark sky (the 1887 object even lacked any head!). In fact, these three objects
are likely the 'faintest' in terms of coma brightness among all of the Great
Comets in history.

J.Bortle