Sky & Telescope - February 2019 - 56

FEBRUARY 2019 OBSERVING
Deep-Sky Wonders

wind from the extremely hot star along
the 2's inner curve pounding against a
surrounding molecular cloud. The star
is about 12,000 light-years distant and
will only survive for an astronomically
brief time before it destroys itself in a
spectacular supernova explosion.
One of my favorite sights in Canis
Major is NGC 2362, also named the Tau
Canis Majoris Cluster for its brightest
star. This is a pretty cluster even at 23×
in the 130-mm scope, showing radiant Tau (τ) closely guarded by several
lesser lights. It becomes quite lovely at
102×, with 25 stars, including one very
near Tau, drawn to Tau like moths to
a ﬂame. The gathered moths envelop
Tau within a triangle whose narrowest corner points south-southwest, and

several strays trail northward from the
triangle's base. At 164× I count 30 stars
spanning 9′, none close to rivaling Tau's
blue-white splendor. The 10-inch scope
at 171× teases out 45 stars and brings to
mind a dazzling brooch with Tau as the
showpiece jewel.
NGC 2362 is a very young star
cluster. According to the WEBDA database (univie.ac.at/webda), it's about 8
million years old and 4,500 light-years
away from us.
While in the neighborhood of NGC
2362, I like to climb 1.7° northnorthwest to drop in on the optical
double star h3945 (HJ 3945). This is
a much-loved pair for many amateur
astronomers, who often compare it
to summer's Beta (β) Cygni by call-

Near the Dog Star
Object
Sirius

Type
Double star

Mag(v)

Size/Sep
11.1″

−16° 43′

46.0m

−20° 45′

7h 18.5m

−13° 14′

6′

18.7m

−24° 57′

5.0, 5.8

26.4″

16.6m

−23° 19′

9′ × 8′

09.9m

−18° 30′

−1.5, 8.4

M41

Open cluster

4.5

39′

Bright nebula

~10½

9′ × 6′

h3945
Sh 2-301

Open cluster
Double star
Emission nebula

Dec.

45.1m

NGC 2359
NGC 2362

RA
6h

3.8

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.

FE B RUA RY 2 019 * SK Y & TELESCOPE

ing it the Winter Albireo. Through my
105-mm refractor, the stars are widely
separated at 28×. The primary star
looks ﬁ relight-gold, but the companion
doesn't appear to have the blue-white
glow I see in the companion to Albireo.
Instead, I usually perceive it as white,
sometimes with a touch of yellow.
What colors do you see?
Let's ﬁnish our tour with the seldomvisited emission nebula Sharpless
2-301, centered 12′ north-northwest of
the 6th-magnitude star HD 54958 (HIP
34617). Sh 2-301 is easy to pick out
with a narrowband ﬁlter using the 130mm scope at 37×. It appears vaguely
roundish and harbors one faint star.
The ﬁlter is unnecessary at 102×, and
the nebula grows irregular in brightness with 3 stars nested in the most
conspicuous part. A star 2.3′ southwest
of the trio inhabits a dimmer area of
the nebula's main mass, which sprawls
across 5′. Diaphanous mist wafts north
from the 5′ mass and fades away a bit
before reaching a tight little arc of three
stars. A 10th-magnitude star marks the
nebula's southeastern edge, accompanied by a yellow, 7th-magnitude gem
farther out. Give this little-known
wonder a try!
¢ Contributing Editor SUE FRENCH visits the realm of the Dog Star as often as
possible in the winter observing season.

SH 2-301 SK E TCH: R AUL LEON; NGC 2362: JIM THO M MES

p Left: The bright nebula Sharpless 2-301 resembles an irregular triangle in the eyepiece, with three stars embedded in the brightest part. This sketch
shows the view through a 14.5-inch f/3.8 reflector at 118×. Right: Giovanni Hodierna discovered the open cluster NGC 2362 before 1654; it was independently (re)discovered by William Herschel in 1783. This young cluster includes about 60 stars.

http://univie.ac.at/webda

Sky & Telescope - February 2019

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