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60 AUSTRALIAN SKY & TELESCOPE JULY 2016

Try our list of the

Top20starsclusters

asyoutourthrough

the history of

southern deep sky

discoveries.

GLENCOZENSANDJUDITHGOODEN

Sparkling

southern clusters

Although small, the Jewel Box, or NGC 4755, is one of the

classic southern open star clusters. Located between the

star Mimosa in the Southern Cross, and the Coal Sack

nebula(bottomoftheimage),itisastand-outobject

through even small apertures.

ESO/ESA/HUBBLE/DSS2/DAVIDE DE MARTIN (ESA/HUBBLE)

W

hich are the ‘best’

open and globular star

clusters in the southern

sky? While astronomers in the

Northern Hemisphere have the

Messier catalogue to guide them,

here in the south we lack a similar

list. However we can be guided by

two outstanding astronomers of

the 18th and 19th centuries whose

observations point us in the right

direction. Between them, these two

men found most of the open and

globular clusters the southern sky

has to offer.

First up is Frenchman, Nicolas-

Louis de Lacaille (1713–62). In

1751 and 1752, observing from

Cape Town with just a crazily

small ½-inch refractor, he found

most of the bright open clusters of

the southern sky. Well-educated

and well-financed, he produced

a catalogue of 42 clusters and

nebulae as well as a catalogue of

9,776 stars.

In contrast, Scotsman James

Dunlop (1793–1848) was not well-

educated and could not afford

a good telescope. Nevertheless,

during 1826 he found most of

the bright globular clusters in

the southern sky. Observing

from Hunter St, Parramatta in

New South Wales, with a home-

made 9-inch speculum reflector

(equivalent to a modern 15-cm

reflector), Dunlop produced a

Southern sky tour