Sky and Telescope - June 2017 - 68

Dark Nebulae

SL 7

HD 143009

Dark Targets in the Southern Wolf
Object

Alt. ID

Mag(v) / Opacity

Size

RA

Dec.

B228

SL 12, SL 13

6, 5

240′ × 20′

15h 45.0m

-34° 31′

Bernes 148

GN 15.42.0

9.5

3.0′

15h 45.2m

-34° 17′

SL 11

-

6

150′ × 40′

15h 57.0m

-37° 48′

NGC 5986

-

7.6

9.6′

15h 46.1m

-37° 47′

SL 7

-

6

60′ × 10′

16h 01.8m

-41° 20′

SL 14

Bernes 149

6

60′ × 70′

16h 09.4m

-39° 08′

B231

-

6

50′ × 40′

16h 38.4m

-35° 25′

B233

-

6

10′ × 40′

16h 43.7m

-39° 49′

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.

68

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

lar cloud 450-500 light-years from
Earth and a member of our local galactic neighborhood (it's found in what's
known as Loop I, next to our Local
Bubble and just opposite the famous
Taurus Dark Cloud).
Sometimes referred to as the Dark
Wolf Nebula, Lupus 1 is dominated by
a long ridge of darkness several degrees
long and about 1° wide. Oriented
northwest-southeast, this tangled
absorption cloud was cataloged as B228
by Barnard, who described it as a "large
vacant region . . . strongest marked at
the north end" in his Catalogue of Dark
Objects in the Sky.
The Sandqvist Lindroos catalog
breaks Lupus 1 down into more manageable pieces in terms of your ﬁeld of
view: The northwest section of B228 is
SL 12; the southeast section is SL 13.
If you can manage a 1½ or 2° ﬁeld of
view, you can compare SL 12 and SL 13
more easily. Like Barnard, Sandqvist
and Lindroos considered the northern
condensation to be darkest, classifying
SL 12 as a 6 on the opacity scale, with
SL 13 coming in at a 5.
Because molecular clouds are lively
star-forming regions, it's not unusual
to ﬁnd bright nebulosities - emission
nebulae, reﬂection nebulae, HerbigHaro objects - interrupting their deep
reaches. Observers of Lupus 1 will ﬁnd
an interesting reﬂection nebula, Bernes 148 (GN 15.42.0), at roughly the
midway point of the dark spine of B228.
An estimated 3′ across, Bernes 148 is
visible at low power, and that's how
you'll want to ﬁnd it, hopping off the
nearby brighter stars, Psi2 (ψ2) Lupi and
HD 140784. Low power will also help
you compare the brightness of Bernes
148 with the neighboring stars. In my
estimation, it's brighter than the stars
surrounding it.
To pull the nebula into clearer view,
you'll need to change to a higher-power
eyepiece, because you're going from
observing an object that's many degrees

BERNHARD HUBL

t BOLD AND BEAUTIFUL The yellow-orange
K-type star HD 143009 marks the western
edge of SL 7. Look for the triangular "bite" of
stars cutting into the darkness to the southeast
of the star.
Sky and Telescope - June 2017

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