SLOAN DIGITAL SKY SURVEY
skyandtelescope.org • JUNE 2020 55
Through my 105-mm refractor at
122 ×, I see Izar’s snug primary and sec-
ondary as gold and white, respectively,
which matches their spectral types of
K0 and A0. However, many observers
see the secondary as bluish, a common
color-contrast illusion experienced
when a yellow, orange, or red star is
seen close to a fainter star that’s not
strongly colored. The companion star
is only 2.8′′ north-northwest of its
primary, and you may need a magnifi -
cation of more than 200× to separate
them when the seeing (atmospheric
steadiness) is poor.
Farther west we come to NGC 5466,
the only globular cluster in Boötes.
Look for it 1.5° northeast of the 6th-
magnitude star 11 Boötis. Although the
cluster has a ghostly surface brightness,
I can detect it through 15×45 image-sta-
bilized binoculars. The globular appears
fairly large through my 130-mm refrac-
tor at 23×. I estimate that it would just
fi ll the space between two fi eld stars
(8th and 9th magnitude) about ½°
to the cluster’s north-northwest and
8.4′ apart. A 7th-magnitude, yellow-
orange star sits 20′ east-southeast of the
cluster. At 102×, NGC 5466 presents
a slightly brighter core that’s elon-
gated north-south for 3¼′. The cluster
remains fairly bright to a diameter of 5′
and then gives way to a gossamer halo.
A few extremely faint stars pop in and
out of view.
In my 10-inch refl ector at 187×,
NGC 5466 fl aunts many chains of faint
to very faint suns beading an unevenly
bright haze, while isolated halo starsare set against a sable sky. Switching
to my 15-inch refl ector at 216×, NGC
5466 is a gorgeous, well-resolved, and
very loose cluster with ragged edges.
Many stars of varied brightness grace
the cluster, some of the brightest hem-
ming the star-dappled core and molding
it into a 5′ triangle pointed southwest.
A line of several stars dangles from
the globular’s southwestern fringe and
trends south-southeast.
NGC 5466 is high above the plane
of our galaxy, about 52,000 light-years
from the Sun and 53,000 light-years
from our galaxy’s center. NGC 5466
sports a lengthy tail of tidal debris
stripped from the orbiting cluster when
it passed near the galactic center while
plunging through the galaxy’s disk. The
tail’s following arm extends at least 15°
southeast, and the leading arm reaches
across Canes Venatici and into Ursa
Major. Part of the tail is kinky, and a
2012 study by Hanni Lux (University
of Nottingham, UK) and her colleagues
used its peculiar structure to probe the
shape of our galaxy’s dark matter halo.
Now we’ll call on the fl at galaxy
NGC 5529, which rests 52′ northwest of
the 4.8-magnitude, yellow-orange starHD 125351. Flat galaxies are disk-like
galaxies, seen edge-on, that appear at
least seven times longer than wide.
NGC 5529 is faint, very slender, and
grows brighter toward the center as seen
through my 130-mm scope at 63×. It
spans about 3′, running west-northwest
to east-southeast. NGC 5529 is nestled
in a distinctive star fi eld that includes
a short, three-star (magnitudes 10.9
to 13.5) line near the galaxy’s eastern
tip and a large, six-star zigzag topped
by a 10th-magnitude beacon west of
the galaxy. Folks with 16-inch or larger
scopes should look for the galaxy’s thin
dark lane and the two dim companion
galaxies to the south (PGC 50952 and
PGC 50925).
Large-scope enthusiasts may also
like to try the more challenging fl at
galaxy UGC 9242, located 1.8° north-
west of Gamma (γ) Boötis. Whereas
NGC 5529 is nine times longer than
wide, UGC 9242 is a needle-thin 17
times longer than wide. With my
10-inch scope at 89×, I can just see
its very dim, elongated core sprouting
short fainter extensions. A 13th-mag-
nitude star is perched 1.3′ southeast
of its center. At 115× I see only 1.3′ ofKangarooNGC 5529PGC 50925PGC 50952