Leo Triplet

This was an image that was posted before its time. My original intent was to get eight hours each of red, green and blue and then try some hydrogen alpha to see if I could get anything. I got my eight hours of green but only managed 72 minutes of red and 93 minutes of blue before a tree put an end fo data acquisition for the season. I should have been more careful about getting at least some data on each filter each night but I blithely assumed I’d have plenty of time and an exceptionally cloudy and rainy spring taught me the folly of that.

When I went to process the data the noise level on the red and blue channels was 16 times higher than the green. I was afraid that it would show in the final result but the Mure Denoise script in PixInsight did a great job in noise reduction and I was careful in my stretch to keep the noise from showing up. All together it turned out better than I had hoped! I opted for the “face” framing — a lot of people see the three galaxies in this orientation as the “expressionless face” emoji: 😑.

The galaxies are 35-42 million light years away and part of a larger group of galaxies in Leo. The top left galaxy is M65 and top right is M66. The bottom galaxy is NGC 3628, informally known as the hamburger galaxy. Though all three galaxies are spirals they are each in a different orientation with M66 being nearly face on and NGC 3628 being edge on. M65 is somewhere in the middle.

Processing was relatively straightforward. You can see the astrobin link for the technical details.

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