The Caldwell Objects

stars of this Milky Way region sail up and over
the pole until, by February, the Perseus Arm of
our home spiral galaxy dominates the view high
in the north after sunset. And it is here that many
amateurs will train their telescopes on some of
the sky's most prominent star clusters and stellar
associations, including the famous Double
Cluster (Caldwell 14), M34, and the Alpha Persei
Association. But there is a rather distinctive
cluster, NGC 1528, which is casually overlooked
in favor of its more popular neighbors. Located
only about 1¾° east-northeast of 4th-magnitude
Lambda (λ) Persei in the Champion's knee, NGC
1528 shines at magnitude 6.4 and makes a decent
naked-eye challenge for anyone under dark skies.
It is a fine object whose brightest members will
start to appear to the dedicated observer in even
the smallest of binoculars.
At 23x in the Genesis the cluster appears
large and bright, with a veil of well-resolved
suns scintillating in front of a fuzzy backdrop of
fainter ones. Brent Archinal catalogs 165 stars in
NGC 1528, with the brightest shining at
magnitude 8.7. The cluster's brightest stars form
a teardrop-shaped asterism that is elongated
along a northwest-to-southeast axis; its narrow
tip points to the southeast. In Star-Hopping for
Backyard Astronomers, Alan M. MacRobert notes
that through a 6-inch reflector under suburban
skies a dark U-shaped bay can be seen at the
cluster's western end, where it is outlined by
seven bright stars. This dark bay is but one of
many wisps of darkness that meander through
the region. Under the dark skies of Hawaii the
cluster appears to be composed of shards of
starlight separated by dark cracks, as if a crystal
teardrop had accidentally shattered on a sheath
of black ice illuminated by moonlight.
434
6
N G C 4 4 9 0
T y B p a e r S : r p G e i a d r l ( a S p x l B y e d c )
C o C n a : V n e n s a t i c i
RA: 12 h 30.6 m
Dec: +41° 38'
Mag: 9.8
SB: 13.0
Dim: 5.6' x 2.8'
Dist: 25 million light-years
Canes Venatici harbors a wealth of extragalactic
treasures, and NGC 4490 is one of the more
prominent ones. This peculiar galaxy lies a mere
40' northwest of 4th-magnitude Beta (β) Canes
Venaticorum (Chara), and it is an easy target for
small-telescope users. The 19th-century British
observer Rev. T W Webb . described NGC 4490 as
a "[l]ong, easily resolvable" nebula. Indeed, the
galaxy's size, shape, and brightness rival those of
some of the more fashionable Messier galaxies in
neighboring Coma Berenices, such as M88, M99,
and M100. At a distance of 25 million light-years,
however, NGC 4490 is half as far away as they
are and, with a diameter of 36,000 light-years,
less than half as big.
A chaotic late-type spiral, NGC 4490 is inclined
65° from face on and is a most fascinating
system, with a ringtail core wrapped in a cocoon
of stellar filigree and Η II regions. The galaxy's
northwestern end looks warped, and it is here
that bizarre drips of starlight make a dogleg to
the north, to yet another pool of tortured
nebulosity surrounding the galaxy's companion,
NGC 4485. In high-resolution images taken with
large telescopes, NGC 4490 looks like an
eviscerated galaxy, one whose entrails have been
ghoulishly ripped from the carcass and tossed
wildly asunder. Through the 4-inch NGC 4490 is
a flying-saucer-shaped lens of light with faint
extensions.
Deep-Sky Companions: The Caldwell Objects