M 91 (NGC 4548) -- Barred Spiral Galaxy in Coma
The Missing Messier Object
When the Messier list was published, no one could find his 91st object. There was
just nothing at the celestial directions that was provided. Speculations, over the
years, ranged that M91 had been a comet, to a dim galaxy that was closest to the
location given. It is now widely agreed that M91 is NGC 2548 and that a simple
error, in recording the original coordinates, was responsible.
M91 is a pretty face-on, barred-spiral galaxy when viewed through the Dobsonian
under dark skies. However, with the refractor from my suburban backyard, at least
on February 13, 2018, it was difficult to locate. With a magnitude of 10.2 spread out
over 5 arcminutes (surface brightness of 13.3) it is one of the more difficult of the
Messier Virgo Galaxy Cluster galaxies to see from my house with the refractor. It
was only with some patience and viewing the galaxy with averted vision was I finally
able to locate it. Maybe, I was a bit too tired, or the atmosphere was not as
transparent as I thought, but M91 proved to be more of a challenge than I expected.
Not necessarily a bad thing.