Each color channel combined in Meade Envisage as collected.
Aligned channels with each other with Meade AutostarSuite.
All channels in Adobe Photoshop 7 via channel merge command.
Stars resized for equality and color saturation adjusted in Adobe PhotoShop 7.0.
Background adjusted to more pleasing color via curves in Adobe Photoshop 7.0
Slight unsharp mask applied at the very end.
I used far too much red data to create this image, making it hard to remove the overall red cast to the image. Maybe some day I'll come back to this
and redo the processing with about half the red data and see if I can't make it sparkle more. It also look like I have some sort of optical issue
with the lower left of this image. I'm not sure what that's about since I hasn't shown up in other images. I'm sure I'll work it out eventually, tho.
Description:
Discovered by Abraham Ihle in 1665.
This was probably the first globular cluster discovered, by Abraham Ihle in 1665. According to Kenneth Glyn Jones, it is supposed (e.g. by Admiral Smyth) that Hevelius may have seen it even earlier, but Halley, De Chéseaux and Messier commonly acknowledge Ihle's original discovery. This globular was included in Halley's list of 6 objects published 1715, and observed by De Chéseaux (his No. 17) and Le Gentil as well as by Abbe Nicholas Louis de la Caille, who included it in his catalog of southern objects as Lacaille I.12. Charles Messier, who cataloged M22 on June 5, 1764, states that it is also included in John Bevis' English Atlas.
M22 is a very remarkable object. At 10,400 light years, it is one of the nearer globular clusters. At this distance, its 32' angular diameter, sligtly larger than that of the Full Moon, corresponds to a linear of about 97 light years; visually, it is still about 17'. It is visible to the naked eye for observers at not too northern latitudes, as it is brighter than the Hercules globular cluster M13 and outshined only by the two bright southern globulars (not in Messier's catalog), Omega Centauri (NGC 5139) and 47 Tucanae (NGC 104) - this is the ranking of the four brightest in the sky.
