M2, imaged by Ron Brecher.

M2, imaged by Ron Brecher. Credit: Ron Brecher

Ron Brecher

Ontario, Canada

BIG STL-11000M camera, Baader LRGB filters, 10″ f/6.8 ASA astrograph, Paramount MX. Guided with STL-11000’s internal guider, Focus with FocsMax and all controlled with CCD Commander. Acquistion, guiding and calibrationusing Maxim-DL. Registration, Integration and all other processing in PixInsight. Shot from my SkyShed in Guelph, Ontario. No moon. Average transparency and average seeing.

81x3mL, 12x10mL, and 10x3m R, G and B, all unbinned. (total 7hr 51m).

Complete processing details available with the web post – http://astrodoc.ca/m2/

M2 is a bright globular cluster located in the constellation Aquarius. Globular clusters — about 150+ of them — orbit around the main body of the Milky Way Galaxy and contain several hundred thousand to a million stars. This one has about 150,000 stars, the brightest being red and yellow giants. But there are a lot of hot blue stars as well. The colour depends on the temperature — red stars are cooler and blue stars hotter). I can see this object with my naked eye from a dark site — barely. I have to use averted vision (looking slightly away from it so its image falls on the edge of your visual field, which is more sensitive in dim light). It’s a pretty splash of stars through the eyepiece in any size of telescope, but to see the colours of the cluster stars well you need to image it (although there are stars nearby that are colourful in the eyepiece). This cluster is so eye catching that it is easy to miss seeing some of the many galaxies in this field. Examples are in the extreme bottom right and near the left edge not far from the top.

The data for this image was collected in September 2013, before my website was launched. The original image earned an Astronomy Magazine Online Picture of the Day in October 2013. I like the new version better for having a more natural looking core, with no burnout, more natural colours, more field stars and galaxies and better noise management.