Hello friends,

The last few weeks of poor observations have not only had disadvantages (even if it is better when the weather is nice). They left time for the processing of images, particularly this one.

The idea was born with @Guillaume Gruntz , with whom we share a lot, following the publication of a colossal work carried out by a group of around fifteen photographers in more than 250 hours. They detected the extensions of M51 like never before, including in Ha.

https://astrob.in/7hwtz0/0/

Guillaume wanted to try this detection and for my part I wanted something with more resolution. We first thought of short exposures with the T350 for the galaxy... It wasn't bad. But seeing the exposures in luminance accumulate, we changed caliber.

Exceptionally, we have combined data from the T1000, published in 2021 by the Omicron team, with those from Guillaume's T250 f/4. 90% of the data is New here.


During the last ten days, between data transfers, intermediate versions and shared rendering choices, we worked hard and finally settled on the next image. It results from compromises and corrections between all 3 with Serge Brunier.

 Don't miss the FULL in 6000 pixels, here is a centered crop :





It is a compromise result that we are proposing, the different mixing stages of which would take far too long to explain in detail. Basically the LSB (far tidal steam) comes from the T250, as well as the Ha. The galaxy up to mid-light comes from the T1000, as well as the faint galaxies and stars in the background of the sky. The nearby extensions are T1000 + T250. We are at around MAG 24 with the old STX compared to a little over 22.5 with the T250. It remains consistent.


The dynamics are monstrous and to keep a balanced visual appearance, the galaxy is left in highlights and shines brightly. The Ha was integrated into the red layer. Finally, the RGB color comes from a mix of the 2 telescopes. The image of the T1000 has been reduced a bit and that of the T250 enlarged reasonably. Finally we kept noise in the extensions. We can smooth these extensions even more, even completely, but that would distort this extremely faint signal too much. It's already a bit muggy there.

For sharing here is the 58h L, already free of a large part of halos in "special" pretreatment (there are still some left). GHS Histogram strectched with SIRIL + a mask on the galaxy. We can clearly see the tidal structures and it is already surprising.




Omicron Team thanks Guillaume very much for this sharing and this achievement. We will never have the telescope time to attack this type of LSB. But as it is less the diameter than the F/D ratio, the darkness of the sky and the exposure time that matter for these extensions, this sharing allows us to access them .


There you go... We're quite happy with it. Hopefully it will take you on a journey too.


Clear skies. 
J.F.