Sky and Telescope - July 2018 - 69
That got me wondering if sky transparency and darkness were responsible for the
difference, so I next compared my deep
M27 sketch made at the Oregon Star Party
to a recent sketch made from my lightpolluted driveway, both using my 28-inch
scope. Sure enough, the pinched waist is
more pronounced in the sketch from home.
Of course, the apparent shapes of all
deep-sky objects are greatly inﬂuenced by
the darkness and transparency of the night
sky, but what's notable in M27's case is that the
trademark dumbbell shape is more obvious under a moderately light-polluted sky.
Then again, under a dark sky with my 28-inch scope I see
more than just the dumbbell shape. The rounded rectangle
becomes just as obvious as does the complete oval noted by
Messier, and together they give M27 its robust and distinc-
t PINCHED WAIST A 28-inch sketch of M27 as
seen from my driveway - note how pinched the
waist area appears compared to my larger, deeper
tive character. Each of these main shapes
includes details of varying subtlety and is
worthwhile exploring one by one.
The brightest and most sharply deﬁned parts
of the Dumbbell are the two opposing arcs that make up the
north and south ends of the dumbbell shape. These H II arcs
are unevenly bright and are two of the most detailed areas to
study at higher magniﬁcation, particularly where they meet a
lumpy line of uneven nebulosity that runs diagonally through
the center of the Dumbbell. Especially interesting are the
subtle striations in both arcs.
p DETAILS EMERGE My deep sketch (enhanced contrast) of the Dumbbell Nebula made with my 28-inch f/4 Newtonian shows the features described in the article. Note how the eastern and western extensions of the faint wings that complete the oval shape of M27 push out into the outer
halo. The striations in the northern and southern arcs are prominent. I used magnifications from 155× to 408× under the dark, transparent skies of the
Oregon Star Party over three nights. Nearly five hours of observing time went into this sketch.
s k y a n d t e l e s c o p e . c o m * J U LY 2 0 1 8