We had hoped to combine our new data with data from 2013 and 2015, but the last two nights the seeing and transparency have been best ever for us, to the point where the old data added nothing or made it worse, and the old stuff has been consigned to the outer darkness.
Luminance 7 hrs in 1 hr subs, RGB 2.5 hrs per channel in 30 min subs. Aspen CG16M on 20" PlaneWave.
Mild deconvolution on L, then very strong arcsinh stretch, meticulous setting of zero point on each channel to foothill of histogram. Colour is almost as it came out of the camera, excepting for a slight increase in blue, and a large increase in saturation. Last of all, lashings of wavelet sharpening. Doing that after the nonlinear stretch seems to produce the least artifacts.
NGC 5128 is accepted to be a dusty edge-on spiral (meat pattie) being gobbled up by a much older giant elliptical. Consequently, we would expect to see intense blue dots around the edges of the meat pattie, representing bright young stars at the collision zone. We would also expect to see the sesame seed buns being orange hued (not blue or white) because they are composed of extremely old stars with no new star formation.
The relativistic jet from the central black hole heads off toward ten o'clock. Two parts are visible. The inner part, well within the sesame seed bun, comprises a bluish chain-o-ponds. The outer part, well beyond the bun and extending to the top left corner of the image, comprises discrete intensely blue dots and patches, and several very faint but quite visible complex continuous arcs, reminiscent of a solar prominence tracing magnetic field lines.
The faint ring structure in the outer halo is not well seen in this single night of L. We might be able to see it if we combined the image with that from previous years. If you download the original image and increase the brightness, you can see hints, but more interestingly, you can see very faint blurry extensions to the galaxy heading off toward top left and bottom right, a bit like a pair of Noddy-style night-caps.
There are a surprising number of distant galaxies visible given the closeness to the Milky Way - we counted 30 with distinct morphology - including five or six seen straight through 5128 itself.
Rather happy with what we got, after a month-long nightmarish technical drought.
We can never go too deep on this one. The 1.5 to 1.8 sec arc seeing was pretty rough compared with say New Mexico, but we'll be thrilled if we an get more nights with conditions as fine as we had here, and try to get more on the rings and particularly the jet. .
NEW 2 June 2017
We've now doubled the exposure. 16 hours of Lum, and 5 hours per channel of RGB, for a total of 31 hours observing time. New full size image here. Of course doubling the exposure produces only incremental rather than game-changing improvements, we think it is better.
The background is now much less gritty. We've processed it to bring out the very faintest details in the faint lobe toward ten o'clock or so, at the expense of overall punch.
In the outermost extensions of the relativistic jet, you can see a wide and diffuse super-faint red jet with much brighter and sharper, but still faint discrete blue blobs and arcs.
Although the absolute colours are somewhat arbitrary, we can see that the outer halo is relatively pink, indicating older cooler stars, and the inner core relatively blue, indicating hot young stars. We've not done anything naughty or selective to produce that differential effect.
We've been very careful to produce as much contrast as we can in the meat pattie without burning anything to black. There is now more dark detail in the very darkest dust lanes in the meat pattie.
The distant background galaxies are a little clear and more definite now.
In a separate exercise, we've shot 7 hours of H-alpha. This has proven so ridiculously faint that, sadly, it has not been possible to combine it with this LRGB image, and we will publish it separately. However, it confirms all the features in the outer jet that we've described here: a broad fat H-alpha stripe with tiny, discrete sharper streaks and dots and arcs that here show up as blue.
Hi Mike & Trish,
That's a great effort.
I thought that it could be sharpened a bit more
so I tried it & you seemed to have hit the limit for a global sharpen.
Therefore I tried some blurred layer mask sharpening in various areas -
as per Ken Crawford's "digging out the details" video -
because they could be sharpened a bit more but not the whole picture.
I hope you don't mind - I attach a small area that I worked on?
The difference is only tiny & some people may not even notice it.
Do you think it's worthwhile?
The top part of the jet is particularly well represented. There is a wonderful subtle red stream going through the blue bits as well.
I wonder what process is occurring to form such a jet so far from the actual merging area?
Greg.
Thanks muchly Greg. The outermost part of the jet, essentially touching the top of image, is especially intriguing, and we hope to eventually tease it out better with more exposure. My understanding is that the jet is produced by the central supermassive black hole, and is unrelated to the collision. Quasars are where much more violent jets in very distant galaxies are pointing straight at us. This one is so special because it is so close, and we can see the jet even though it's not pointed straight at us.
Quote:
Originally Posted by Peter Ward
I have to say the image looks a little soft to me, but has great depth.
Nice burger...with the lot!
Hi, Peter. I'm guessing that by soft you mean lack of local contrast, most noticeably in the dust streaks, rather than FWHM. We think the fainter stars are very tight, but the dust detail is nowhere near as contrasty as in your image. Am I right? Glad you like the depth. (Never mind the quality, feel the width, as the tailor said). It's only a single night each of L and RGB (we're trying to get more L tonight but cloud is predicted later), but we're seeing real-looking stuff in the upper part of the jet that we've not seen before.
Quote:
Originally Posted by alpal
Hi Mike & Trish,
That's a great effort.
I thought that it could be sharpened a bit more
so I tried it & you seemed to have hit the limit for a global sharpen.
Therefore I tried some blurred layer mask sharpening in various areas -
as per Ken Crawford's "digging out the details" video -
because they could be sharpened a bit more but not the whole picture.
I hope you don't mind - I attach a small area that I worked on?
The difference is only tiny & some people may not even notice it.
Do you think it's worthwhile?
cheers
Allan
Thanks Allan, that is very kind of you and we're delighted for you to experiment. Your right hand thumbnail is very noticeably more contrasty than the left. Shows that more can be done.
Thanks Allan, that is very kind of you and we're delighted for you to experiment.
Your right hand thumbnail is very noticeably more contrasty than the left. Shows that more can be done.
Best,
Mike
Thanks Mike,
I think I did touch the curves as well for a bit more contrast
so it wasn't only sharpening.
The most is at the blue area at the top of the galaxy
where I applied the strongest mask.
More detail has started to emerge.
I think your image is worth cropping of the central area
& stacking with 3 x drizzle in DSS.
There is a bit more detail that can be pulled out than what you see.
( that's as long as you've dithered each frame? )
You could then copy & paste the drizzled galaxy back into the original!
I really like the galaxy itself, but have to agree with Peter that the image is a little soft, stars are not particularly round and there is a lot residual red blotches in several places and noise mottling around the stars.
I would guess the 1 hour subs did not help here. I mean, a LOT can happen in a 15 minute image never mind 1 hour. Unless of course your entire system and your local conditions support subs of this length.
Again though, I really like the galaxy and the jet is presented well.
Very well done!
Lovely deep image....I love the blue jet....very colourful stars.....
Top notch!
Cheers,
Tim
Thanks Tim. We may have overdone the colour a tad given we only have one night's worth of RGB, but the colour in the jet seems to be a defining feature and worth highlighting.
Quote:
Originally Posted by Spookyer
Yes very good guys, should be very happy with that.
brett
Thanks, Brett.
Quote:
Originally Posted by alpal
Thanks Mike,
I think I did touch the curves as well for a bit more contrast
so it wasn't only sharpening.
The most is at the blue area at the top of the galaxy
where I applied the strongest mask.
More detail has started to emerge.
I think your image is worth cropping of the central area
& stacking with 3 x drizzle in DSS.
There is a bit more detail that can be pulled out than what you see.
( that's as long as you've dithered each frame? )
You could then copy & paste the drizzled galaxy back into the original!
cheers
Allan
Thanks again, Allan. The images were dithered. We do that routinely, but we can see that we need to increase the dithering distance because our camera produces very strong ghosting from the hourly focus run, and we need strong dithering to avoid these ghost images overlapping each other.
As you know all our camera control, acquisition, and processing software is our own. I don't yet understand the mathematics of drizzling, and until I do, our images will sadly go undrizzled.
Quote:
Originally Posted by Martin Pugh
I really like the galaxy itself, but have to agree with Peter that the image is a little soft, stars are not particularly round and there is a lot residual red blotches in several places and noise mottling around the stars.
I would guess the 1 hour subs did not help here. I mean, a LOT can happen in a 15 minute image never mind 1 hour. Unless of course your entire system and your local conditions support subs of this length.
Again though, I really like the galaxy and the jet is presented well.
thanks for posting.
cheers
Martin
Nice to hear from you, Martin.
Especially glad that you liked the galaxy and the jet in particular, because to us that is what is most magically special about this galaxy. NGC 5128 without fine detail in the outermost parts of the jet is like a hamburger without beetroot.
We'll try to address hairy stars and red blotches when we get more data.
Still not sure what you and Peter mean by "soft". Do you mean lack of local contrast in the dust filligree, for example?
Once again, thanks for taking the time to look at the image closely and giving us some valuable pointers as to how we can improve it.
Thanks again, Allan. The images were dithered. We do that routinely, but we can see that we need to increase the dithering distance because our camera produces very strong ghosting from the hourly focus run, and we need strong dithering to avoid these ghost images overlapping each other.
As you know all our camera control, acquisition, and processing software is our own. I don't yet understand the mathematics of drizzling, and until I do, our images will sadly go undrizzled.
I prefer to just try it & see if it can make a difference.
It may not work so powerfully for you as I doubt that you're under sampled?
I prefer to think of drizzle as extra information that is hiding in your data
that can be used rather than as a trick.
Talking of tricks -
when I first watched Ken Crawford's "digging out the details" video
I thought - he's cheating - "finger painting" so to speak.
Then when I thought about it - he's not -
certain areas of any deep sky image will have a greater
signal to noise ratio than others.
To do a global sharpening would falsely enhance noise & make
the picture look worse but
in other areas where the signal to noise ratio is higher, then
more sharpening using a blurred layer mask is not cheating -
it's just making the most of your data -
it's adding the icing on the cake.
I look forward to seeing your results with extra data.
It is very nice Mike and Trish! I opened it up and stretched it a bit harder, you've gone quite a bit deeper in the outer halo than what is being shown here! It's fantastic
You've captured the jet really nicely, quite a bit of red and what appears to even be some blue (or just coincidental blue stars).
You are correct about the formation of the jet, it is known as an AGN (Active Galactic Nuclei). It has only been in the last few years that we've come to realise that the three different types of AGN aren't actually different as much as it is just us viewing it from different vantage points.
I do agree with Peter that it does look a bit soft, particular compared to his shot. As you mention, I don't think this has anything to do with your FWHM, just sharpening somewhere towards the end of the line. The attached images demonstrate what I mean. I've done nothing other than use Unsharp Mask and destroy your background and all of your stars
Looking forward to seeing how deep you can go Mike and Trish
I think it is a great image M&T. Colours are well balanced, detail in the galaxy is very good and stars are just joy to look at
It might be interesting to blend in some Ha data into your splendid image. It would help highlighting star forming regions within the galaxy, and could help in bringing up fainter bits of the jet. Here is a link to my attempt at capturing the jet in Ha with my 4" scope: http://www.astrobin.com/full/250830/0/?nc=user
Lovely image M&T! I like all the little galaxies in the background too. That jet everyone is talking about, is that the little blue streak at the top left of the frame?
I've been reluctant to image this galaxy as it looks like a processing nightmare.
Last night we more than doubled the Luminance, and had a go at reprocessing in the light of everyone's comments. We can make the core more crunchy, or the jet a tiny bit cleaner (less than we hoped. Colour seems really important), but we've not yet got a satisfactory new version to show.
Quote:
Originally Posted by Atmos
It is very nice Mike and Trish! I opened it up and stretched it a bit harder, you've gone quite a bit deeper in the outer halo than what is being shown here! It's fantastic
You've captured the jet really nicely, quite a bit of red and what appears to even be some blue (or just coincidental blue stars).
You are correct about the formation of the jet, it is known as an AGN (Active Galactic Nuclei). It has only been in the last few years that we've come to realise that the three different types of AGN aren't actually different as much as it is just us viewing it from different vantage points.
I do agree with Peter that it does look a bit soft, particular compared to his shot. As you mention, I don't think this has anything to do with your FWHM, just sharpening somewhere towards the end of the line. The attached images demonstrate what I mean. I've done nothing other than use Unsharp Mask and destroy your background and all of your stars
Looking forward to seeing how deep you can go Mike and Trish
Thanks Colin, and thanks for the added effort! Now we understand.
Quote:
Originally Posted by Slawomir
I think it is a great image M&T. Colours are well balanced, detail in the galaxy is very good and stars are just joy to look at
It might be interesting to blend in some Ha data into your splendid image. It would help highlighting star forming regions within the galaxy, and could help in bringing up fainter bits of the jet. Here is a link to my attempt at capturing the jet in Ha with my 4" scope: http://www.astrobin.com/full/250830/0/?nc=user
Hopefully you will get many opportunities to add more data and to go even deeper :-)
That's fantastic, Suavi. We'd seen your stunning image before, but now we were able to register it with ours, and see that your H-alpha plume goes way off the page past the edge of our image, and hugely past the edge of the galaxy proper. Most inspiring !!
Quote:
Originally Posted by cometcatcher
Lovely image M&T! I like all the little galaxies in the background too. That jet everyone is talking about, is that the little blue streak at the top left of the frame?
I've been reluctant to image this galaxy as it looks like a processing nightmare.
Many thanks, Kevin.
The blue streak is part of it, but it goes right to the left end of the top of frame and beyond. Suavi's H-alpha image (see his link above) shows it goes way, way beyond the edge of frame, right to the top of the ultra-faint upper lobe shown by Mike Sidonio. Rolf Olsen's (180 degree rotated) extraordinary optical image shows it clearly. Interestingly, a multi-wavelength shot using huge professional scopes only shows the inner part.
Quote:
Originally Posted by RickS
Great work, M&T! I noticed the hairy stars and red blobs but they don't detract from the image materially. The jet is the icing on the cake.
Cheers,
Rick.
Thanks muchly Rick. We can see that the image has both strengths and weaknesses.
