Globular cluster M56


Ron Brecher

Ontario, Canada

SBIG STL-11000M camera, Baader LRGB filters, 10″ f/6.8 ASA astrograph, MI-250. Guided with STL-11000’s internal guider, Focus with FocsMax and all controlled with CCD Commander. Acquistion, guiding and calibration using Maxim-DL. Registration, integration and all processing in PixInsight. Shot from my SkyShed in Guelph, Ontario. Average transparency and average seeing.

12x10mL and 5x3mL unbinned and 10x3m R, G and B binned 2×2. (total 3hr45m).

Complete processing details at

Globular cluster M56, in Lyra, the Harp, lies about 33,000 light years away and its stars have the mass of about 230,000 times that of the Sun. It sometimes goes unnoticed because it shares the general area of the sky with a few other iconic objects: the Ring Nebula (M57), the “Double Double†– a pair of tight, bright, white double stars – and Vega, the 5th brightest star in the sky. One of the things I like about globular clusters is how different they all are from each other. This one resolves quite well right to the core, and is set in a rich Milky Way star field. Another thing I find interesting about these objects is that they tend to be very old. This one is estimated to be 13.7 billion years old, and may have been captured by the Milky Way from another galaxy. It’s orbit around the Milky Way is retrograde, meaning it is in a direction opposite to most other similar objects.

The data for this image was collected in May 2013, almost a year before my website was launched, but I don’t think I have distributed it previously.