http://www.skyandtelescope.com.au 63NGC 2808: Dunlop found this
magnificent globular cluster and
wrote of it, “a very bright round
nebula, about 3 ́ or 4 ́ diameter, very
gradually bright to the centre. This
has a fine globular appearance.” This
magnitude-6.2 globular is 31,300
light-years away and 14 ́ across.
NGC 3201: This globular has a
low concentration of stars, is only
16,000 light-years away, magnitude
6.9 and 20 ́ across. Dunlop found
it, describing it as “A pretty large
pretty bright round nebula, 4 ́ or 5 ́
diameter, very gradually condensed
towards the centre, easily resolved into
stars; the figure is rather irregular,
and the stars are considerably
scattered on the south preceding (SE)
side: the stars are also of slightly
mixed magnitudes.”
NGC 5139: Also known as
Omega Centauri, Edmond Halley
found this superb globular cluster
from St Helena Island in the South
Atlantic in 1677. It is magnitude 4.0,
55 ́ diameter and 17,000 light-years
away. Dunlop described it as “a
beautiful large bright round nebula,
about 10 ́ or 12 ́ diameter, easily
resolvable to the very centre; it is a
beautiful globe of stars very gradually
and moderately compressed to the
centre ... This is the largest bright
nebula in the southern hemisphere.”
The galaxies NGC 4945 and NGC
5128 are nearby.
NGC 6397: This one was found
by Lacaille, with Dunlop describing
it as “a pretty large nebula, extended
nearly in the parallel of the equator,
brightest and broadest in the middle
... The nebula is resolvable into
stars.” This low-concentration
globular cluster is only 7,500 light-
years away, 30 ́ in diameter and
magnitude 5.3.
NGC 6541: Nicolò Cacciatore
discovered this one on March 19,
1826 from Palermo, Sicily while
searching for a comet. Dunlop
independently discovered it on
July 3, 1826. He saw “a very bright
round highly condensed nebula,
about 3 ́diameter. (He could) resolve
aconsiderableportionroundthe
margin, but the compression (was)
so great near the centre, that it would
requireaveryhighpower,aswell
aslight,toseparatethestars;the
stars are rather dusky.”It is 24,500
light-yearstothismagnitude-6.3
globular cluster, which has a
diameter of 15 ́.
NGC 6723:This one was
discovered by Dunlop in 1826,
too. It is 28,000 light-years away,
magnitude6.8anddiameter15 ́.
Dunlop saw“a beautiful bright
round nebula, about 3.5 ́diameter,
moderately and gradually condensed
to the centre. This is resolvable.
Themoderatecondensation,and
thebluishcolourofthestarswhich
composeit,giveitaverysoftand
pleasant appearance. This is rather
difficult to resolve, although the
condensation is not very great.”
Bluishbrightanddarknebulaeare
nearby.
NGC 6752:Dunlop also
discovered this one, describing it
as“a pretty large and very bright
nebula,5 ́or6 ́diameter,irregular
roundfigure,easilyresolvedintoacluster of small stars, exceedingly
compressed at the centre. The bright
partatthecentreisoccasionedbya
group of stars of some considerable
magnitude when compared with
those of the nebula. I am inclined to
thinkthatthismaybetwoclusters
inthesameline;thebrightpartisa
little south of the centre of the large
nebula.”This magnificent starfish-
shaped, magnitude-5.3 globular
clusteris30 ́acrossand13,000
light-years distant.
Sothereyouhaveit—10each
of the best open and globular star
clusters in the southern sky. In
subsequent articles, we’ll provide
similarlistsofnebulaeand
galaxies. Until then, we encourage
you to get your telescope out and
hunt down some of these amazing
interstellar sights.✦Glen Cozenshas spent more than 35 years observing and
makinglistsofdeepskyobjects.In2008,hecompleteda
doctorate on the first three catalogues of southern clusters
and nebulae made by Nicolas Louis de la Caille in 1751,
JamesDunlopin1826andJohnHerschelfrom1834to- He would like to acknowledge the support given to
himbyhisJamesCookUniversityPhDsupervisor,
Dr Graeme White. Adelaide-based Judith Gooden is a
keen observer of the southern skies.
NGC 104, or
47 Tucanae, is
a showpiece
globular cluster
deep in the
southern sky.ESA/HUBBLE (DAVIDE DE MARTIN)/ ESA/ESO/NASA PHOTOSHOP FITS LIBERATOR/DSS2