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Old 20-09-2017, 03:35 PM
markas (Mark)
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Join Date: May 2012
Location: Melbourne Australia
Posts: 467
M55 through haze

GCs aren't the most entertaining subjects, but faced with high level haze, streaks of cirrus clouds and a lousy forecast for the rest of this dark period, I settled for M55, as I thought a GC was the best chance for a result in the conditions.

As luck would have it, the worst conditions were in force during half of the blue imaging, so a lot of Pixinsight cleaning up was necessary. After that, minimal processing: a little decon to sharpen the image a bit, Pixinsight's new Photometric Colour Calibration, and Histogram Stretch.

Although M55 has very low metallicity, it also has a relatively large number of 'blue stragglers' - thought to be the result of relatively recent star mergers and collisions.

ASA10N f/3.6; Moravian G3-16200; DDM85A; Astrodon filter set.
RGB only; 2.5min subs; total exposure 3 hours 20 min. FOV of this crop approx. 32' x 25'
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