WWW.ASTRONOMY.COM 47
W REGION 3
We begin our final region with our third
golden double star, Almach. A gem for
telescopes of all sizes, the 2nd-magnitude
primary sports a 5th-magnitude sap-
phire companion 10" away. Jumping
northwestward to 5th-magnitude Phi (φ)
Cassiopeiae, we arrive at the adorable
Owl Cluster (NGC 457), one of the most
popular showpieces at amateur gather-
ings and an object named by Astronomy
Editor David J. Eicher. The magnitude 6
cluster has two prominent stars (Phi^1
and Phi^2 ) as its eyes, a roughly T-shaped
arrangement of dimmer stars, and two
isolated suns marking the owl’s feet.
Now let’s center Eta Cassiopeiae in
our telescopes. Dubbed the Easter-Egg
Double, the 3.5-magnitude topaz primary
shares the field with a magnitude 7.5 lilac
companion 13" to the northwest. A short
1½ ̊ hop to the southeast brings us to
another treasure: the irregularly shaped
Pacman Nebula (NGC 281). The
comma-shaped, 30' glow contains a
4'-wide open cluster (IC 1590) at its core.
Next up is a triad of disparate clusters.
We begin with the Widow’s Web Cluster
(NGC 7790) about 2½ ̊ northwest of
Caph. Although the cluster shines dimly
at magnitude 8.5, its two dozen or so
stars are compacted into a 5'-wide region
of sky and appear as a highly concen-
trated east-west-trending Y-shaped web
of starlight against a rich Milky Way
backdrop. NGC 7788, a 9th-magnitude,
9'-wide cluster, lies only about 15' to the
northwest, while the 10th-magnitude
open cluster Berkeley 58 is about 20' to
the southeast, looking like a 5'-wide
ghostly gathering of minute stars.
Moving northward to 3rd-magnitude
Gamma Cephei, we look about 5½°
southeast for the 35"-wide disk of the
Bow-tie Nebula (NGC 40). The 12th-
magnitude planetary’s magnitude 11.5
central star overpowers the surrounding
glow. Magnifications greater than 150x
are required to perceive the dark cavity
between the central star and its shell.
Let’s slip over to 3rd-magnitude Alfirk
(Beta Cephei), then about 3° southwest to
the 8th-magnitude Iris Nebula (NGC
7023) — a high-surface-brightness ref lec-
tion nebula surrounding a 7th-magnitude
star. Here is one of the first regions where
astronomers found direct evidence of
dust grains in molecular clouds.
Another 3 ̊ sweep toward the south-
west brings us to the small (4') 11th-
magnitude barred spiral galaxy NGC
6951 also in Cepheus. This overlooked
extragalactic wonder was discovered byAmerican astronomer Lewis Swift with
a 4½-inch refractor. Images show it as
seen through galactic cirrus, or clouds
of interstellar dust.
Returning to Draco, we head to 4th-
magnitude Phi Draconis and look about
2¾ ̊ northeast for the 10th-magnitude
Lost-in-Space Galaxy (NGC 6503).
German astronomer Arthur von Auwers
discovered this 6'-long dwarf spiral with
a 2.6-inch refractor. Seen only 16 ̊ from
edge-on, it somewhat resembles a glow-
ing meteor train.
We end our tour just 4 ̊ south and
slightly east of NGC 6503 at one of the
sky’s finest planetary nebulae: the 8th-
magnitude Cat’s Eye Nebula (NGC
6543). Lying just 3' east of an 8th-
magnitude star, this sizable 23"-wide
nebula shines with a pale green color
even at low power. High powers will
separate well its sharp 11th-magnitude
central star from its luminous inner
ring. A tenuous outer shell of nebulous
matter surrounds these features, giving
the planetary a slightly elongated
appearance.
I hope you enjoyed exploring the
Golden Triangle. The objects we reviewed
are but a sampling of the wonders in the
region. But, as with any journey, it’s
always best to leave some things unseen
for when we next return.Stephen James O'Meara is a
contributing editor of Astronomy and the
author of numerous books on observing.The bright and beautiful Lost-in-Space Galaxy
(NGC 6503) occupies an empty region of space
known as the Local Void, which spans some
150 million light-years. ADAM BLOCK/NOAO/AURA/NSF
The core of the elegant and magnificent Cat’s Eye
Nebula (NGC 6543) is encapsulated by a series of
concentric shells, formed when the nebula’s dying
star ejected material at regular 1,500-year intervals.
ADAM BLOCK/MOUNT LEMMON SKYCENTER/UNIVERSITY OF ARIZONAEmission nebula NGC 281 — commonly called the Pacman Nebula due to its resemblance to the classic
video game character — features a dark dust lane cutting across its face. FABIAN NEYER