Sky and Telescope - October 2018 - 55

NW

tp In the eyepiece at low magnifications, NGC

NGC 68 04 IM AG E: VOLK ER WENDEL / STEFA N BINNE WIES / JOSEF PÖPSEL;
NGC 68 04 SK E TCH: SUE FRENCH

6818 appears nonstellar and boasts a bright
blue-gray color. More magnification will draw out
the more ghostly parts of the annulus and mute
the blue to a soft blue. Martin Germano's image
of the nebula (left) represents a total exposure of
75 minutes with a 14.5 f/5 Newtonian reflector. The Hubble Space Telescope image (right),
which was processed from data captured across
optical wavelengths, shows how stellar winds
have elongated the nebula's shell.

with a hue that seems robin's-egg blue
to me. Only suspected at 164×, the
12.4-magnitude central star makes a
deﬁnite appearance against the highsurface-brightness nebula at 234×. The
planetary has a slight elongation that
points a bit north of the neighboring
star. Judging by how many NGC 6891
disks could ﬁt between the central
star and the 12th-magnitude star, the
nebula is about 10″ across. With the
15-inch scope at 345×, the nebula sports
a faint, rounder halo.
Cygnus is the home of NGC 7027,
also known as the Green Rectangle and
the Magic Carpet Nebula. These nicknames are the brainchildren of Kent
Wallace, the ﬁrst for its appearance
through his 20-inch scope. He coined
the second name after reading about
a Hubble image of the nebula being
described as a hot coal on a carpet.
NGC 7027 is a bright, aqua, starlike
spot with a halo when seen through the
130-mm scope at 37×, and a small disk
blossoms at 102×. The planetary appears
oblong northwest-southeast at 164× and
ﬂaunts its color even better, while at
234× its southeastern end appears narrower and not quite as bright. The color

morphs into a deep sky-blue, still surprisingly bright. NGC 7027 is intriguing
through the 15-inch scope. My sketch
on the next page was made at 345×, and
the features to search for are labeled.
Another brilliant planetary nebula is
NGC 7662 in Andromeda, aka the Blue
Snowball. Its common name springs
from an article by Leland S. Copeland
(S&T: Feb. 1960, p. 216), who describes
the nebula as "looking like a light blue
snowball." It's readily visible as a very
small, blue disk in my 130-mm scope at
23×. At 102× it appears annular with a
somewhat dimmer fringe and interior.
The nebula remains nicely blue and is a
beautiful sight at 164×. The bright ring
looks slightly oval northeast-southwest,
and a 13th-magnitude star lies off its
east-northeastern edge. NGC 7662
stays remarkably bright and blue even
at 234×. The annulus seems irregular
in brightness and more subdued in the
northwest. My sketch on the next page
shows the view of this stunning nebula
through the 15-inch scope at 493×.
NGC 40 in Cepheus is called the Bow
Tie or the Scarab nebula. The origin of
these monikers is hazy, but it seems to
be the consensus that Bow Tie refers to

the visual impression given by its two
brighter arcs, while Scarab comes from
the beetle-like shape seen in images.
NGC 40 is a nice little blue-gray disk
dotted by its central star in the 130-mm
refractor at 48×. At 164× it's vaguely
oval, and the long sides seem a bit
brighter than the interior or the ends.
The nebula is a lovely greenish-blue in
the 15-inch scope. At 216× its sides are
quite deﬁnitely brighter, with the western arc enhanced in the north, while the
ends fade away into the background sky.
Messier 76 in Perseus bears a few
nicknames: the Little Dumbbell, the
Barbell, and the Cork. The ﬁrst two
indicate a supposed resemblance to the
Dumbbell Nebula (M27) in Vulpecula,
while the last depicts the shape of its
bar. M76 is moderately faint and corkshaped in the 130-mm refractor at 48×,
and a power of 102× exposes brighter
caps at the ends of the cork. Adding
a narrowband ﬁlter brings out faint
extensions ballooning from the cork's
long sides, while an O III ﬁlter nicely
accentuates the lumpy structure of the
bar. Examining M76 at 164×, I estimate
a cork length of 1¾′. The nebula is gorgeous through the 15-inch scope, and
my sketch on the next page shows the
view at 345×. While visiting, look for
the vividly orange, 6.7-magnitude star
12′ east-southeast of this planetary.
We'll wind up our tour with NGC
246 in Cetus, nicknamed the Skull
Nebula for its appearance in some

pu Like NGC 6818,
NGC 6804 shows some
distortion thanks to the
effects of the stellar wind
on outflowing material. The
author used an O III filter
to pull out the nebula's
details (above). Images
such as the one shown at
right, which was captured
with a 60cm-Hypergraph in
secondary focus, can help
guide your observations at
the eyepiece.
sk yandtelescope.com * OCTOBE R 2 018

55
http://www.skyandtelescope.com
Sky and Telescope - October 2018

Table of Contents for the Digital Edition of Sky and Telescope - October 2018
