ph . Astronomy . Gallery . Astrophotos by George Liakos

Jewel Box Cluster (NGC 4755)

Posted 2007 February 22 @ 01:11

George writes that this is one of his favourite visual observing targets. The photo above was taken at the prime focus of a Meade LX90 8-inch SCT (f/20). He used a Canon EOS 350D, set at ISO 400, and stacked 15 30-second exposures.

The cluster was first recorded by Lacaille and announced in his 1755 catalogue. James Dunlop (1827) observed it from Australia and noted it's characteristic triangular figure "with a multitude of very small stars on the south side."

Sir John Herschel gave it it's famous name. He observed it during his stay at the Cape of Good Hope with an 18inch f/13 speculum telescope. He recorded it as "the central star (extremely red) or a most vivid and beautiful cluster of from 50 to 100 stars. Among the larger there are one or two evidently greenish; south of the red star is one 13th mag, also red; and near it is one 12th mag, bluish."

He later wrote of it as "an extremely brilliant and beautiful object when viewed through an instrument of sufficient aperture to show distinctly the very different colour of its constituent stars, which give it the effect of a superb piece of fancy jewellery.

NGC 4755 can be seen from February to September and is number 52 on the Top 100 Deepsky Objects list.

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Keywords: Astronomy, deepsky observing, deep sky observing, astrophotography, George Liakos