JOHANNES
HEVELIUS,^
FIRMAMENTUMSOBIESCIANUM(^1687
)^ /^PUBLIC^DOMAINFoxfi re
Nights
Vulpecula’s dearth of bright
stars is offset by its wealth
of deep-sky objects.V
ulpecula, the Fox, has no bright
star to draw our eyes his way and is
overshadowed by the showier constella-
tions around him. Yet this inconspicu-
ous star fi gure has an amazing wealth
of deep-sky wonders. If you take the
time to visit them and make them your
own, then the Fox will hold a special
place in your heart and never seem
ordinary again.
Our fi rst fi ery splendor in the Fox
is the constellation’s brightest star,
4.4-magnitude Alpha (α) Vulpeculae,
a red giant 80 times bigger across and
400 times more luminous than our Sun.
Alpha is a lovely optical double desig-
nated Σ I 42, meaning the 42nd entry
in the fi rst appendix to F. G. W. Struve’sdouble-star catalog. Its unrelated suns
are more than 7′ (a r c m i nut e s) apa r t
and are easily seen with steadily held
binoculars. The colorful components are
widely separated in my 4.1-inch refrac-
tor at 17×. The primary appears orange,
and its 5.8-magnitude yellow neighbor
sits north-northeast. The bright star is
about 200 light-years closer to us than
its apparent companion.
The open cluster NGC 6800 is
located 36′ northwest of Alpha. My little
refractor at 17× reveals a very pretty
sprinkling of faint stars spanning 15′.
At 87× I count two dozen stars, the
brightest strung along the outline of
an oval with a large central void. My
10-inch refl ector at 118× doubles the
star count, but the edges of the clus-
ter become very ill defi ned. William
Herschel discovered this cluster while
sweeping the sky with his 18.7-inch
speculum-metal refl ector in 1784. He
aptly described the group as a cluster of
coarsely scattered bright stars inter-
mixed with faint stars.
NGC 6793 is a confusing open
cluster 2.8° south-southwest of Alpha54 SEPTEMBER 2019 • SKY & TELESCOPE
7RFHOHEUDWH\HDUVRI6XH
)UHQFK˪VVWHOODUFRQWULEXWLRQV
WR6N\ 7HOHVFRSHZHZLOOEH
VKDULQJWKHEHVWRIKHUFROXPQV
LQWKHFRPLQJPRQWKV:HKDYH
XSGDWHGYDOXHVWRFXUUHQWPHD
VXUHPHQWVZKHQDSSURSULDWHBut if you tame me, then we shall need
each other. To me, you will be unique in all
the world. To you, I shall be unique in all
the world.
— Fox to the title character in
The Little Prince,
Antoine de Saint-Exupéry, 1943and 1.8° east-northeast of 1 Vulpeculae.
It hides in a starry fi eld that renders
it tricky to pick out, which is probably
why the object isn’t plotted on many
modern star atlases. William Herschel
discovered the group in 1789 and called
it a scattered cluster of considerably
bright stars, pretty rich, of an irregular
fi gure, above 15′ in extent. Yet most
modern catalogs list the group as being
only 6′ or 7′ in diameter.
My own notes refl ect this ambiguity.
While observing with my 4.1-inch scope
at 17×, I logged a small, granular-look-
ing patch with a few faint stars. At 87×
the cluster showed two triangles of stars
— one bright, one faint — plus a few
very dim stars in 3½′. Outliers stretch
the group to about 6′. The northernmost
star in the bright triangle is the double
star h886, its 10.5-magnitude primarypThe constellation Vulpecula, the Fox, was
created by the Polish astronomer Johannes
Hevelius for his 1687 celestial atlas Firmamen-
tum Sobiescianum. Consequently, European
star atlases published in the 18th and 19th
centuries frequently depicted Vulpecula carry-
ing Anser, the Goose, in it s long jaws.SEPTEMBER 2019 OBSERVING
Deep-Sky Wonders by Sue French