Sky and Telescope - November 2017 - 55

Deep-Sky Wonders by Sue French

Square Galaxies
Spend some time roping this herd of faint fuzzies in the Great Square of Pegasus.

O

ne of the unmistakable stellar
landmarks of the autumn sky is
the Great Square of Pegasus, which
you'll ﬁnd cozied up to the meridian on
this month's all-sky map. As Garrett
P. Serviss writes in his ever charming
book Astronomy with an Opera-Glass,
the Great Square "at once attracts the
eye, there being few stars visible within
the quadrilateral, and no large ones in
the immediate neighborhood to distract
attention from it."
The Great Square corrals a herd of
galaxies, little-known to most amateur astronomers. Let's round up a few
of those that are a bit of a challenge
for medium-sized telescopes from my
semirural home. We'll start with one
of the easier catches, NGC 7678, which
is found 1.2° west of the pulsating red
giant star 71 Pegasi (magnitude 5.3 to
5.6). This face-on spiral galaxy is about
140 million light-years away from us,
yet bright enough to see even through
78

23h 40m

23h 30m

HD
221394

NGC 7678

Halton Arp included NGC 7678, which lies west of 71 Pegasi, in his Atlas of Peculiar
Galaxies as an example of "spiral galaxies: one heavy arm." Deep-sky images make the
heavy arm more apparent; in the eyepiece, the galaxy will offer a roundish glow with a
slight brightening toward the core.

my 130-mm refractor at 37×. Its ﬁlmy
glow is neatly framed in a 2.4′-tall triangle of three stars, magnitudes 11 and
12. At 91× the roundish galaxy coffers
a small, slightly enhanced core and ﬁlls
much of the triangle.
23h 20m

61

UGC 12515
7628

Star magnitudes

+28°

60

7741

RICK JOHNSON
CREDIT

23h 00m

`

UGC
12591

PEGASUS

3
4
5
6
7
8

23h 10m

+26°
56

+24°

p
71

o

7678

+22°

My 10-inch reﬂector at 166× shows
NGC 7678 to better advantage, displaying a plump, 1½′-long oval that leans
northeast. With averted vision, I see
darker regions northeast and southwest
of the core, indicative of dusky, interarm regions within the spiral.
Now we'll move on to shier game in
the guise of the elliptical galaxy NGC
7628, located 2.2° north of 5th-magnitude Tau (τ) Pegasi and just 21′ west
of a 6th-magnitude, yellow-orange star.
Through the 10-inch scope at 115×, NGC
7628 is merely a faint little spot. At 166×
the galaxy intensiﬁes toward the center
and makes a 1′-tall isosceles triangle
with two stars to its south, magnitude
13.1 and 13.8, while at 213× it becomes
slightly oval and spans roughly ½′.
NGC 7628 is included in our tour
largely because it's good practice for our
next target, which looks about the same
size but has a slightly fainter magnitude
and lower surface brightness. British
amateur Mark Stuart pointed these
galaxies out to me. He was looking at
NGC 7628 and noticed that his star
chart plotted another galaxy nearby,
right next to a star. Stuart was quite
s k y a n d t e l e s c o p e . c o m * N O V E M B E R 2 0 17

55
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Sky and Telescope - November 2017

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