Sky and Telescope - April 2018 - 54

APRIL 2018 OBSERVING
Deep-Sky Wonders by Sue French

Into the Lion's Den
It's deep, it's dark, but this nighttime hideaway is also full of galaxies.

T

he den of the celestial lions, Leo
and Leo Minor, is adorned with the
ashen light of myriad far-ﬂung galaxies awaiting our admiration. Since Leo
is far and away the more recognizable
of these starry felines, let's begin our
pursuit of their deep-sky wonders by
prowling through his share of the den.
Leo's iconic feature is the sickleshaped asterism that marks his head
and heart, but some skygazers picture
it as a backward question mark. Our
initial leonine quarry is a galaxy trio
10h 00m
+34°

9h 55m

north of the Sickle, composed of NGC
2964, NGC 2968, and NGC 2970. You'll
ﬁnd them arrayed along a shallow arc,
with each galaxy smaller and dimmer
as you work your way from southwest to
northeast.
The brightest member of the triad is
NGC 2964, perched 1.9° north of the
5.6-magnitude star 15 Leonis. In my
130-mm refractor at 37×, the galaxy
bares a brighter heart and crowns a
distinctive arrangement of eight 9th- to
12th-magnitude stars that outline an

9h 50m

9h 45m

9h 40m
2942

HD 85030

LEO MINOR
3021

3003
+33°

3067

LEO

2944
3011

+32°

2970

20
3071

2968
2964

UGC 5272
2981

+31°

+30°

54

A PR I L 2 018 * SK Y & TELESCOPE

15

Star magnitudes

UGC 5364
5
6
7
8
9
10

18′-tall shark ﬁn. At 63× NGC 2964
becomes an east-west oval covering
roughly 2′ × 1′. NGC 2968 materializes
6.2′ to the northeast, watched over by
a 12th-magnitude star roosting 3.6′
north-northeast. At 102× NGC 2968
looks oval and points back toward
NGC 2964, which brightens moderately
toward the center. Using averted vision,
NGC 2970 joins the scene as a little,
fuzzy dot 2.9′ east of the 12th-magnitude star. My 10-inch reﬂector at 115×
coaxes out a small, concentrated core
within NGC 2968.
This galaxy triplet is thought to be a
true group. A neutral-hydrogen bridge
connects NGC 2964 and NGC 2968,
while a tail reaches out to NGC 2970.
The local motions of these galaxies and
their relative nearness to us conspire to
make redshift-based distances unreliable. Only NGC 2964 has a signiﬁcant
number of redshift-independent distance determinations. Using their mean
as a value would place the trio at 62
million light-years. Experienced astroimagers have captured visible material
around NGC 2970 that may stem from
past galaxy-galaxy interactions.
Crossing the border into Leo Minor,
we'll ﬁnd NGC 3003 21′ west-southwest
of the 7.9-magnitude star HD 85030.
The galaxy appears slender and very
faint in the 130-mm scope at 48×.
At 102× its brightest region spans 2′
and slants a bit north of east. Pallid
extensions run farther west than east
and stretch the length to perhaps 5′.
Through the 10-inch scope at 166×, the
galaxy's face seems slightly patchy.
In the 130-mm refractor's 48× view,
NGC 3003 shares the ﬁeld with a little
fuzzy spot snugged against an 11th-
Sky and Telescope - April 2018

Table of Contents for the Digital Edition of Sky and Telescope - April 2018
