Sky and Telescope - January 2017 - 56

JANUARY 2017 OBSERVING
Deep-Sky Wonders

halo. NGC 1232A turns up as a detached
shred of mist off the larger galaxy's eastsoutheastern side. It sits about halfway
between and south of an imaginary line
between NGC 1232's center and the gold
9th-magnitude star to its east.
Our quintet's ﬁnal party is NGC
1187, centered 46′ north of Tau3 (τ3)
Eridani. It has fairly low surface brightness, but it's not hard to spot through
the 130-mm scope at 63× as long Tau3 is
kept out of the ﬁeld of view. The galaxy
covers roughly 3′ × 2′, and an 8.8-magnitude star lies off the northwestern tip.
Nearly aligned with the halo, a somewhat brighter, bar-like region inhabits
the interior. At 117× the galaxy wears a
mottled face. The ﬂeecy appearance is

quite pronounced in my 10-inch reﬂector at 118×, making NGC 1187 rather
pretty. The galaxy grows gently brighter
toward the center, and at 171× I see a
slight brightness pip at its heart.
For our ﬁnale, let's swoop down to
the river's next meander, which shelters

River of Galaxies
Object
NGC 1407

Galaxy Type
Elliptical

Mag(v)

Size/Sep

9.7

RA

Dec.

4.6′ × 4.3′

3h

40.2m

-18° 35′

39.5 m

-18° 41′

NGC 1400

Lenticular

11.0

2.3′ × 2.0′

3h

NGC 1393

Lenticular

12.0

1.9′ × 1.3′

3h 38.6 m

-18° 26′

NGC 1402

Barred lenticular

13.6

0.8′ × 0.6′

3h 39.5 m

-18° 32′

13.2

1.6′ × 0.8′

3h

40.1m

-18° 27′

38.9 m

-18° 21′

IC 343

Barred lenticular

NGC 1391

Barred lenticular

13.3

1.1′ × 0.5′

3h

NGC 1394

Lenticular

12.8

1.3′ × 0.4′

3h 39.1m

-18° 18′

NGC 1300

Barred spiral

10.4

6.2′ × 4.1′

3h 19.7m

-19° 25′

11.8

2.2′ × 1.9′

3h

19.2m

-19° 06′

9.9

7.4′ × 6.5′

3h

09.8 m

-20° 35′

NGC 1297

Lenticular

NGC 1232

Spiral

NGC 1232A

Barred Magellanic spiral

14.6

0.9′ × 0.8′

3h 10.0 m

-20° 36′

NGC 1187

Barred spiral

10.8

5.5′ × 4.1′

3h 02.6 m

-22° 52′

9.9

12.6′ × 3.3′

4h

12.1m

-32° 52′

12.5

1.3′ × 0.9′

4h 12.0 m

-32° 51′

NGC 1532

Barred spiral

NGC 1531

Lenticular

Angular sizes and separations are from recent catalogs. Visually, an object's size is often smaller than the
cataloged value and varies according to the aperture and magnification of the viewing instrument. Right
ascension and declination are for equinox 2000.0.

56

J A N U A R Y 2 0 1 7 * SK Y & TELESCOPE

the interacting galaxies NGC 1532 and
NGC 1531, berthed 1.5° northwest of
Upsilon4 (υ4) Eridani. I nabbed this farsouthern pair at the Winter Star Party
in Florida. Even in my 105-mm refractor at 17×, NGC 1532 is a lengthy band
of haze. It looks nice at 87×, about 6′
long with a brighter elongated interior.
A 7th-magnitude star gleams 13′ eastnortheast. NGC 1531 is visible with
averted vision as a very faint smudge
closely inspecting the northwestern
ﬂank of its much larger companion,
but it shows up much better at 122×.
This is an alluring duo when viewed
through my 10-inch scope. At 118×
NGC 1532's halo bridges approximately
9′. The brighter region is about 3½′ long,
slightly tilted with respect to the halo,
and it coffers a small, bright, round core
with an almost starlike nucleus. NGC
1531's oval is ¾′ long, fairly uniform in
surface brightness, and looks as if it's
taking a nosedive into its companion.
Deep images show remarkable tidal
tails drawn out of NGC 1532 by the
encounter with its companion. Distance
estimates for this striking pair have
trended upward with time, from as little
as 44 million-light years in the 1980s to
as much as 67 million light-years during
this decade.
■ SUE FRENCH welcomes your comments
at scfrench@nycap.rr.com.

ESO / IDA / DA NISH 1.5M / R. G ENDLER A ND J.-E. OVA LDSEN

u Interacting galaxies NGC 1532 and NGC 1531
may be difficult to distinguish in your eyepiece.
Use averted vision to locate the smudge of NGC
1531 on the northwestern edge of its larger
companion.
Sky and Telescope - January 2017

Table of Contents for the Digital Edition of Sky and Telescope - January 2017
