Sky & Telescope - June 2019 - 31

NGC 4030: ESO / P. G ROSB Ø L; NGC 3310: N ASA / ESA /
HUBBLE HERITAG E TE A M / STSCI / AUR A

ou've probably marveled at the grand spiral structure
in the Whirlpool Galaxy, teased out the ethereal pinwheel of M101, and traced the delicate branches of
Triangulum's grandest showpiece, M33. Few deep-sky objects
elicit as much awe as these open-faced spiral galaxies with
their spectacular arching arms. The Messier list contains
several other examples, and you've no doubt enjoyed at least
the brightest of them.
Are there more of these majestic marvels lying just off
the well-worn track? The challenging targets on our tour of
open-faced spirals from the New General Catalogue of Nebulae
and Clusters of Stars might reward the patient and careful
observer with some delightful surprises. They are all well
placed in the June sky.
Learning to eke out faint spiral structure is a useful skill
to cultivate. First, of course, one should employ all of the
tried-and-true techniques for pushing the envelope of visual
detection. You'll want the darkest site you can ﬁnd on a night
of decent sky conditions. Dark adaptation is paramount; take
the time to achieve it and take precautions to preserve it.
Large aperture will be a plus, but don't discount your chances
just because your telescope is of modest aperture. Experiment
with magniﬁcation; ﬁnding the optimum contrast is essential. Most important, however, is simply learning to consider
that there may be faint structure visible beyond what is
initially evident. You're apt to miss what you don't look for.
And, as with any faint deep-sky object, the longer you look
the more you'll see.
Some observers like to view a photograph of an object ﬁrst.
It's quite helpful to know exactly where to look for the fainter
components of a galaxy. The danger, of course, is in imagining you see something just because you know it's there. I
prefer to check the photographs after noting these fainter
features to conﬁrm that what I suspected was really there.
NGC 3310 (Arp 217) lies about 4.5° southwest of the Big
Dipper's bowl and about 10′ south-southwest of a 5.6-magnitude star (HD 92095). A ﬁrst impression is of an abruptly
bright core within a much fainter halo. Further study reveals
a more mottled appearance, and eventually a small northreaching arm becomes visible. A southern arm is less continuous, comprising a string of bright knots, or stellarings.
The term stellaring was probably coined by Brian Skiff
and Christian Luginbuhl in their 1990 publication, Observ-

β
γ

M108
M97

+55°
HD 92095

3310

3631

M109

URSA MAJOR

+50°

3893
M106

χ
4051

3938
67

12h 00m

11h 30m

+45°

11h 00m

p STELLAR NURSERY NGC 3310 in Ursa Major is an example of a
starburst galaxy, where stars are being born at a prodigious rate, especially along the spiral arms.

Prey

Face-on spiral galaxies are
among the most graceful
objects to behold and thus are
totally worth the bit of effort
they require to observe.
sk yandtele scope.com * J U N E 2 019

http://www.skyandtelescope.com

Sky & Telescope - June 2019

Table of Contents for the Digital Edition of Sky & Telescope - June 2019