The Leo Trio – M65, M66 and NGC 3628
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March 17, 2012 – Published in the Bulletin of the Royal Astronomical Society, May 2012
M65 (lower left), M66 (upper left) and NGC3628 are three galaxies in the constellation Leo. This grouping is known as the Leo Trio or Leo Triplet. This group of galaxies is around 30 million light years away. I’ve shot this many times, and I keep getting happier with the result each time! This shot was acquired over about the last 4 or 5 clear nights. I first collected colour data before full moon, when the moon was setting early. For the last couple of nights I gathered luminance (brightness) data using a clear filter (filter is needed to remove infrared and ultraviolet light). In the middle of all this I had some guiding issues, which gave me images with oblong stars (which I deleted rather than using). Fortunately, these issues have now been resolved. I have a few more images on the go, and may get time to do some processing over the next few days… And tonight looks pretty good for imaging too!
Colour data: 3x10mL + 5x5m R, G and B. Luminance Data: 30x5mL. SBIG STL-11000M camera, Baader LRGB filters, 10″ f/3.6 ASA astrograph, MI-250 mount. Guided with internal guider in main camera. Acquistion, guiding, calibration, registration and integration all done using Maxim-DL. All other processing in PixInsight. Shot from my SkyShed in Guelph, Ontario. Various moon and sky conditions (mostly on the low side of average).
Master Colour and Luminance images were made by stacking in MAximDL. Each was separately processed using a fairly typical workflow (background extraction, colour balance, deconvolution, histogram stretch, HDR wavelets, noise reduction, colour saturation, local histogram equalization). Luminance channel was then extracted from the colour image and used as the reference for a Linear Fit on the Master Luminance. This fitted master luminance was then applied to the colour image. Saturation and brightness were tweaked, and a heavily masked unsharp mask was run on the galaxies.