Dear all, here is my latest effort, latest in term of processing since this is clearly a spring object
This shot is about one of the most common targets for the period, M83, the southern pinwheel. But I tried to show something less common on this one.
All started when I composed the luminance channel of this shot. Usually one of the first things I do as I start a processing is to perform a hyper stretch (gaussian) of the original fits looking for the faintest details recorded as well as possible defects. On this luminance I noticed almost immediately the faint arc north of the galaxy
. A quick search on the web turned out it was a known features, first imagined by Malin and than by (very) few others. There is a debate at the moment about its origin, perhaps it is a tidal stream remaining from a former interaction with another galaxy (long gone) or as being one of the very faintest arms of this spiral, somehow a little bit brighter in that position. I found no sure answer about the right answer.
Surprisingly I found only another shot taken by an amateur showing traces of it, the beautiful one taken by Mike and posted on this web some time ago.
I hope so to contribute to the topic with my image
Here is the link:
http://www.glitteringlights.com/Imag...4_vHKgwNm-A-LB
I strongly recommend to check the high res version, 4000x4000 and visible full screen with the usual zoomify page:
http://astrosurf.com/lorenzi/ccd/m83_HaLRGB
You can indeed dive into the field, there are dozen and dozen of background galaxies.
I had to stretch really a lot to show the tidal stream and the outer arms of M83, furthermore I opted to keep the background a little bit brighter than I usual do in order to help the overall visibility. I didn't see so far many pics around showing the great extend of m83, that is pretty amazing!
I also tried my best to keep the image looking natural, although at this "extreme" processing I am not sure to have succeed..
I also added some Ha to increase the visibility of the HII regions.
I hope you will like it
Clear Skies
Marco