Evidently, M102 is the last possibly `missing',
or doubty, Messier object. This means that two opinions on the identity of
this object are common:
- M102 may be a duplication of the
Spiralna galaksija - Spiral Galaxy
M101 (NGC 5457)
in ursa Major,
due to an error of either the catalog author Messier,
or its `discoverer' Mechain.
- M102 may be the
also sometimes called the Spindle Galaxy,
as Messier's catalog description indicates, together with the position
he added later by hand.
Some details on this topic are discussed here.