Sky & Telescope - June 2020 - 25

NGC 6979
NGC 6974

Pickering's
Triangular
Wisp

NGC 6992

NGC 6995

IC 1340

NGC 6960

p SUPERNOVA UNITED (Left) All the individual segments of the nearby Cygnus Loop supernova remnant (noted in the image) are included on the
Sharpless list as Sh 2-103. BIG PLANETARY (Right) Sh 2-290 is one of the closest planetary nebulae visible from Earth, and the only Sharpless
nebula in Cancer.

neatly combined the individual segments of NGC 6960, NGC
6992, NGC 6995, NGC 6974, NGC 6979, IC 1340, and Pickering's Triangular Wisp into Sh 2-103.
About 2° southwest of 2nd-magnitude Sadir (Gamma
Cygni) is the Crescent Nebula (NGC 6888), cataloged as
Sh 2-105. This complex nebula is produced by the stellar wind
from the Wolf-Rayet star WR 136 at its center. The Crescent is
another object that contains a bluish oxygen III (O III) component consisting of a gossamer shell seen along its outer edge.
Continuing about 3° farther along the imaginary line
formed by Sadir and the Crescent brings us to Sh 2-101, the
Tulip Nebula. This moderately bright emission nebula displays
small dark lanes in deep exposures.
For a tough summertime challenge, look 3½° south of
Sh 2-101 and try to image Sh 2-98. As one of the fainter
Sharpless catalog members in Cygnus, it looks like a ghostly
red smoke ring in a rich ﬁeld of brightly colored stars. Like
Sh 2-105, Sh 2-98's glow is caused by energy from a powerful
Wolf-Rayet star, in this case WR 130.
In the northeastern corner of the constellation, Sh 2-124
tends to be overlooked due to its proximity to so many betterknown objects. Lying in a dense star ﬁeld 3.5° northeast of
IC 5146, the Cocoon Nebula, this little nebula is bisected by a
wide, meandering dark lane.
Skipping farther south, the Eagle Nebula in Serpens is
often referred to as M16, but Messier actually cataloged the
open cluster at the Eagle's heart and didn't see the surrounding nebula. Sharpless includes this expansive nebulosity as
Sh 2-49. Long exposures are required to reveal the extended

"wings" of nebulosity that give the nebula its nickname,
while larger instruments producing a higher pixel-scale are
required to get good detail in the central pillars of dark nebulosity. Just 2° north of the Eagle and part of the same tenuous
hydrogen cloud is Sh 2-54, which adds additional interest to
wide-ﬁeld photographs of the area.

Northerly Declinations
Targets in the summer Milky Way remain available to
northern imagers as the nights lengthen during autumn. But
you might also ﬁnd yourself drawn towards other Sharpless
treasures along the Milky Way in Cassiopeia, Cepheus, and
Perseus.
One of the best-known deep-sky objects in this region is
the Bubble Nebula, NGC 7635, denoted as Sh 2-162 on the
Sharpless list. This thin shell of nebulosity is found about
37′ southwest of the open cluster M52 and is being hollowed
out by the strong stellar winds of the young star SAO 20575
within. The Bubble should reveal itself in relatively short
exposures. Slightly more than 1° south-southwest of the
Bubble Nebula lies the expansive Lobster Claw Nebula,
Sh 2-157. The Lobster Claw contains a strong O III component and is particularly colorful when imaged through
narrowband ﬁlters. A wide-ﬁeld astrograph with a 4° ﬁeld can
frame both objects in the same ﬁeld and make a nice composition that also includes another interesting nebula, NGC
7538, also known as Sh 2-158.
Heading west just over the border in Cepheus, 31/3° to the
northeast lies the Cave Nebula, Sh 2-155. This faint target is a
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Sky & Telescope - June 2020

Table of Contents for the Digital Edition of Sky & Telescope - June 2020