This galaxy seems very similar to Centaurus A in that it has a massive faint extended halo and it appears to be a merger of perhaps an elliptical galaxy and a spiral galaxy. There are no other small satellite galaxies for it in sight to explain the disrupted halo.
The shape of the halo with an arrowlike head and ballooning out to a large distorted elliptical ball with a long sweeping arc of tidal stars on top extending out to the rear is fascinating. Also you can see a ring just outside the main spiral.
I wanted to see how deep I can go with the 84% QE ASI183mm Pro and my Astrophysics Riccardi Honders 305mm F3.8 scope at my semi rural home observatory. The answer is plenty deep.
I wasted a lot of subs. Quite a lot of the colour were moon affected and didn't add anything. I found out 2x2 binning is still very useful on these cameras as is maxing out the cooling to -25C. I'll have to do a side by side -25C versus -10C and 1x1 versus 2x2 image on the same night but I think 2x2 makes a lot of sense with this camera as the pixels are only 2.4 microns so it still makes the pixels only 4.8 microns which matches the seeing and optics better. Plus with 20mp you still have good enough resolution.
AP RHA 305, Bisque PME, ASI183mm Astrodon filters.
I love this galaxy Greg and I can see you have had a good hammer at it, great work and overall it looks pretty cool, I love the tight details in the inner disc of the galaxy, looks like a distant rotating star city... but.. re the faint halo stuff...my 10hrs of Lum (with essentially the same scope and also a fairly sensitive camera) from Bortle 3.5 skies, can't really confirm much of your outer halo features, even when heavily stretched? That big ring below the galaxy on the right, looks to me, like a dust bunny that the flats didn't remove properly and I can't find any other images that can confirm any of the other fluff in the field either. Not trying to be mean or anything, as there is clearly a bit of work in this, what do you think?..maybe I have it wrong?
I love this galaxy Greg and I can see you have had a good hammer at it, great work and overall it looks pretty cool, I love the tight details in the inner disc of the galaxy, looks like a distant rotating star city... but.. re the faint halo stuff...my 10hrs of Lum (with essentially the same scope and also a fairly sensitive camera) from Bortle 3.5 skies, can't really confirm much of your outer halo features, even when heavily stretched? That big ring below the galaxy on the right, looks to me, like a dust bunny that the flats didn't remove properly and I can't find any other images that can confirm any of the other fluff in the field either. Not trying to be mean or anything, as there is clearly a bit of work in this, what do you think?..maybe I have it wrong?
Mike
I went and rechecked the luminance as I also wondered initially if that ring was real as it seemed a bit perfect. Yes it was a dust bunny on a flat. Its the opposite though, the raw luminance had no dust bunny so perhaps the dust particle fell off. The flat was putting one there.
There still is a large halo around the galaxy as your image mostly shows but not all of it. There is a hammer like piece at the front and and rounded end at the back. There does seem to be a very faint arc over the top extending to the back. So apart from the dust bunny the rest seems right.
I also have nearly 3 hours of recent CDK17/ML16200 luminance and it shows it quite well also. Your image shows a couple of very faint arcs above the galaxy too. Its quite similar to Centaurus A this way with it oversized halo and shell like structure.
I am in the middle of a repro on this one so I will post it once its done.
Negative dust donuts aside, that is a truly wonderful image of a wonderful galaxy. We can't wait for the next Leo season.
Read somewhere that while the Hamburger is an elliptical galaxy swallowing an edge-on spiral and chewing it up, the Sombero might be an elliptical galaxy that has encountered lots of fresh new intergalactic gas, and is forming a brand new spiral galaxy from scratch, deep inside it, not consuming it in a collision, which is why the Sombrero spiral looks so peaceful and intact.
Perhaps something like that is happening here. The spiral looks to be in such good nick. Perhaps it's a line-of-sight thing, and the big badda-boom is yet to happen.
Negative dust donuts aside, that is a truly wonderful image of a wonderful galaxy. We can't wait for the next Leo season.
Read somewhere that while the Hamburger is an elliptical galaxy swallowing an edge-on spiral and chewing it up, the Sombero might be an elliptical galaxy that has encountered lots of fresh new intergalactic gas, and is forming a brand new spiral galaxy from scratch, deep inside it, not consuming it in a collision, which is why the Sombrero spiral looks so peaceful and intact.
Perhaps something like that is happening here. The spiral looks to be in such good nick. Perhaps it's a line-of-sight thing, and the big badda-boom is yet to happen.
MnT
Interesting hypothesis. I plan to spend some time reworking the image. I got a lot of data on this one but some I wasted as it was moon affected and the difference in the no moon images was striking.
Hi Greg,
I have never seen that much detail on NGC3521. That outer halo is quite spectacular. You have certainly upped the bar on that one.
Cheers
Peter
Last edited by PeterSEllis; 19-07-2020 at 09:02 AM.
That big ring below the galaxy on the right, looks to me, like a dust bunny that the flats didn't remove properly 
and I can't find any other images that can confirm any of the other fluff in the field either. Not trying to be mean or anything, as there is clearly a bit of work in this, what do you think?..maybe I have it wrong? 
