NGC 6752, Caldwell 93, the Great Peacock Globular

Globular Cluster

Constellation: Pavo

RA: 19 10 52.11
DEC: -59 59 04.4

Mag: 5.40 (though Simbad says 6.28)

Size: 20.4'

First let's address a minor controversy: Is this the third or the fourth brightest globular cluster in the sky? For a very long time, Wikipedia claimed it was the third brightest, after Omega Centauri and 47 Tucanae. As a matter of fact, NGC 6752 was APOD on July 5, 2013 (see the picture below), and the info there seems to have been copied straight from Wikipedia. Funny enough, Wikipedia has stated for a long time that the brightness of M 22 is +5.1 clearly making it brighter than NGC 6752. When I started writing this article I noticed that now the Wikipedia page for NGC 6752 says that it is the fourth brightest globular after Omega Centauri, 47 Tucanae and M 22 whew.

ngc6752_2013_07_02dp.jpg
NGC 6572 as imaged by Damien Peach.

NGC 6752 was discovered by James Dunlop on June 30, 1826, who was the first astronomer to systematically observe the southern hemisphere beating John Herschel by over 10 years. Dunlop did more than 40,000 observations from Paramatta, New South Wales, (now called Parramatta) and catalogued nearly 7400 stars between June 1823 and February 1826. He left the Paramatta observatory and started conducting private observations from his home in Paramatta from March 1826 until he returned to Scotland in 1827. Dunlop returned to Australia in 1831 and would stay there until his death in 1848.

The cluster itself is not a very special one. It lies at about 13,000 ly from Earth, making it one of the closer ones, and about 17,000 ly from the galactic center. It is of Shapley-Sawyer Concentration Class IV, meaning intermediate density. Dunlop could discern stars in the cluster, though I don't know what telescope he used to observe it.

So, why choose this cluster then? Well, simply because of it's beauty. I observed the cluster shortly after the solar eclipse in 2019 from Chile using a 12" dobsonian telescope. My notes read:

"Visible to the naked eye. At 28x clearly visible as a large, round glow. At 112x spectacular! A large cluster with no less than five streamers and an arc of stars and a very compact core. Fantastic! Beats M 13!!!"


As always,

"Give it a go and let us know!
Good luck and great viewing!"