This image shows Ptolemy's Cluster, a very bright open star cluster easily visible with the naked eye near the tail of Scorpius. It lies at a distance of 980 light years and has some 80 member stars within its diameter of about 25 light years. The age of these young bright stars is approximately 200 million years.
The cluster was known as a hazy patch in the sky already in antiquity and was first described by the ancient astronomer Ptolemy in 130 AD.
This image was taken with a bright 78% illuminated Moon nearby.
Date: 31st May 2012
Exposure: LRGB: 48:24:24:24m, total 2hrs @ -28C
Telescope: 10" Serrurier Truss Newtonian f/5
Camera: QSI 683wsg with Lodestar guider
Filters: Astrodon LRGB E-Series Gen 2
Taken from my observatory in Auckland, New Zealand