Unusually for us, a bit of PhotoShop finger-painting to bring out some of the ultra-faint stuff, and to increase the central contrast, but I don't think we've put in anything that isn't really there.
To our chagrin, this year's Eagle, though wider field, isn't really showing anything more sharply than our old STL-11000M shot. The main improvement is the inclusion of 6 hrs of [SII].
If we imagine that the dark wedge-shape top centre is the Eagle's head and razor sharp beak, looking down hungrily on the Pillars of Creation (one thinks of Prometheus), then there is either a giant pineapple ring, or more mythologically, a Sisyphean millstone, emerging above and to the right of the head. This structure and its surrounds is really fainter than shown here.
As always, we direct your attention to the tiny "Reluctant Parachutist", seen in profile, whose equipment has let him down, saying his prayers. The Parachutist is to be found to the right of the Pillars.
To the right of the Parachutist is some magnificent, swirly, wispy material strongly glowing deep blue in [OIII] which we haven't really noticed before.
To our left of the Eagle's beak is one standard magnificent dragon, facing to the right. It seems to have caught something to eat.
At the right of the base of the pillars is an H-alpha shock front forming a plateau, or ledge. This ledge is populated with various crouching hell-hounds, which luckily could be viewed as a distant city, with mysterious towers.
Finally, and marginally more scientifically, we note the strong OIII emission on streaming, steaming material evaporating from the "head" of the tallest pillar.
We've stretched the red and blue channels until the image is overall colour neutral. At 16 bits, the final image darks are not burned out, but reduction to 8 bits has clipped the very blackest bits.
3 nM filters. Green: H-alpha 3hrs; Red [SII] 6hrs; Blue [OIII] 6hrs. Aspen CG16M on 20" PlaneWave on MI-750 fork. Field 36'arc, 0.55 sec arc/pixel.
You're cranking them up lately. Gorgeous field. I really like the top part coming down on the central bok swith the cluster in the middle, all those filaments look great. Very 3D.
You're cranking them up lately. Gorgeous field. I really like the top part coming down on the central bok swith the cluster in the middle, all those filaments look great. Very 3D.
Thanks, Marc. Touching wood about the cranking. The gear seems to have settled down, excepting for needing a dew-heater on the secondary on some really wet nights.
Quote:
Originally Posted by Atmos
Amazing job there, you certainly look like you're going after ESO
Thanks, Colin. They're safe for a bit longer.
Quote:
Originally Posted by Paul Haese
Cool 3D feel. Just down the base of the pillars looks very 3D. Huge image too. Nice work.
Cheers, Paul! It's not as sharp as we'd like, and I think I've done the unspeakable and over-sharpened it a bit in an attempt to compensate. Pleased with the relatively clean [SII] though.
Truly magnificent you pair.
Thanks for your imaginative description. I had never been able to see an eagle in this nebula until you described. Now I can see nothing but!
Awe inspiring
Another lovely colour palette Mike and Trish, well done
Very grand
Mike
Thanks heaps, Mike!
Quote:
Originally Posted by gregbradley
Boom, there is the detail in the pillar and great contrast. Nice.
Greg.
Thanks again, Greg. Oh, I wish I could adjust the altimeter and make the observatory a couple kilometers higher.
Quote:
Originally Posted by Stevec35
That's a nice Eagle Mike and Trish. Plenty of good detail.
Cheers
Steve
Thanks, Steve.
Quote:
Originally Posted by DJScotty
Truly magnificent you pair.
Thanks for your imaginative description. I had never been able to see an eagle in this nebula until you described. Now I can see nothing but!
Awe inspiring
Thanks muchly, Scotty. We reckon that finding little dragons and gremlins helps one remember the image, and makes it easier to compare mentally with others. Also lots of fun.
Love the detail. Love the colour. I still have trouble with NB images with red star colouring and wonder what techniques people use to try and minimise that if they wish to deal with it?? ...??Layer some short sub RGB data to the stars only??
Just looking at what different people do .....
The cause of the magenta or red rings is the much greater stretching of [SII] and (to a lesser extent) [OIII] compared with the ubiquitous H-alpha.
We've got a lot to learn, but we're aware of six approaches to dealing with the resultant red or magenta stars.
(0) Ignore them. As that famous Caribbean astrophotographer Bob Marley so aptly put it, in his textbook Confrontation, "Dey say it's just a part of it.". On close inspection, many Hubble and ESO shots have magenta stars. This approach works best if you have a space telescope and tiny stars to start with.
(1) Remove the stars entirely. This involves trying to guess what is "under" the star. A bit like trying to repair an inkblot on a tablecloth by examining the pattern of the cloth and replicating it. Fred (BassNut) and others are good at this. Identify the star mathematically, then use multiple linear regression or the like to interpolate what would have been there. It works really well on smooth nebulosity, but very badly if the star concerned is right over some complex HH jet or shock front that is important to you.
(2) Identifying the stars and desaturating them to white. This is like bleaching a beetroot stain on a tablecloth. It's what we tend to do. It's just a cosmetic fix, but it doesn't require one to pretend to know what is under the star. The first limitation (not so bad) is that one's star-finding algorithm has to be able to find at least 20,000 stars, and to not imagine any, or you'll be left with all the faint ones, or have holes punched in your nebulosity. We try to avoid conspicuous grey rings by just partially bleaching, so the magenta is still there, but no so visually distracting.
The second limitation is that very bright stars take up a huge amount of real estate once they've been stretched to show [SII], and ultimately there's some overlap with the nebulosity. One can then choose between either (a) grey rings in the nebulosity, or (b) choosing to put up with red rings around the brightest stars. We think that's a good scientific solution, but they do stand out like sore thumbs.
(3) Taking RGB exposures of sufficient length that the star in its natural colour will be at least as big and fat and bright as the [SII] after stretching. One then registers the RGB shot to the narrowband shot, and takes the brighter of the two images. That's fair enough, and honest, but for something like say the Norma Supernova Remnant, where the SNR is incredibly faint, it's actually good-bye nebula. The stars overwhelm. It's also a lot of hard work for what is basically a cosmetic fix.
(4) A combination of (1) and (3). One guesses what is under the star and replaces it with a fake guessed background. One then puts smaller, less stretched, RGB stars more or less as place-holders, or eye-distracters, so that you don't see quite so badly how the star removal went.
(5) The final method (which again Fred mentioned to me) is to identify and remove the stars in the red and blue channels only. This works especially well in [OIII] because there tends to be less sharp detail in [OIII] and one doesn't have to guess so hard what to put there instead. One now re-identifies the (now much smaller) star, and bleaches it to white. That method should have the advantages of all and the disadvantages of none. We're yet to master it.
The cause of the magenta or red rings is the much greater stretching of [SII] and (to a lesser extent) [OIII] compared with the ubiquitous H-alpha.
We've got a lot to learn, but we're aware of six approaches to dealing with the resultant red or magenta stars.
(0) Ignore them. As that famous Caribbean astrophotographer Bob Marley so aptly put it, in his textbook Confrontation, "Dey say it's just a part of it.". On close inspection, many Hubble and ESO shots have magenta stars. This approach works best if you have a space telescope and tiny stars to start with.
(1) Remove the stars entirely. This involves trying to guess what is "under" the star. A bit like trying to repair an inkblot on a tablecloth by examining the pattern of the cloth and replicating it. Fred (BassNut) and others are good at this. Identify the star mathematically, then use multiple linear regression or the like to interpolate what would have been there. It works really well on smooth nebulosity, but very badly if the star concerned is right over some complex HH jet or shock front that is important to you.
(2) Identifying the stars and desaturating them to white. This is like bleaching a beetroot stain on a tablecloth. It's what we tend to do. It's just a cosmetic fix, but it doesn't require one to pretend to know what is under the star. The first limitation (not so bad) is that one's star-finding algorithm has to be able to find at least 20,000 stars, and to not imagine any, or you'll be left with all the faint ones, or have holes punched in your nebulosity. We try to avoid conspicuous grey rings by just partially bleaching, so the magenta is still there, but no so visually distracting.
The second limitation is that very bright stars take up a huge amount of real estate once they've been stretched to show [SII], and ultimately there's some overlap with the nebulosity. One can then choose between either (a) grey rings in the nebulosity, or (b) choosing to put up with red rings around the brightest stars. We think that's a good scientific solution, but they do stand out like sore thumbs.
(3) Taking RGB exposures of sufficient length that the star in its natural colour will be at least as big and fat and bright as the [SII] after stretching. One then registers the RGB shot to the narrowband shot, and takes the brighter of the two images. That's fair enough, and honest, but for something like say the Norma Supernova Remnant, where the SNR is incredibly faint, it's actually good-bye nebula. The stars overwhelm. It's also a lot of hard work for what is basically a cosmetic fix.
(4) A combination of (1) and (3). One guesses what is under the star and replaces it with a fake guessed background. One then puts smaller, less stretched, RGB stars more or less as place-holders, or eye-distracters, so that you don't see quite so badly how the star removal went.
(5) The final method (which again Fred mentioned to me) is to identify and remove the stars in the red and blue channels only. This works especially well in [OIII] because there tends to be less sharp detail in [OIII] and one doesn't have to guess so hard what to put there instead. One now re-identifies the (now much smaller) star, and bleaches it to white. That method should have the advantages of all and the disadvantages of none. We're yet to master it.
Best,
Mike
Nicely summarised ...lastly (6) you can't make everyone happy so do what you like
very nice M&T I still remember your last shot of this posted, love that parachuter!
Cheers
Russ
Thanks Russ. We had a look at combining the two images. That produced a small reduction in grittiness in the blackest recesses, but of course no increase in bright detail, as that wasn't photon limited. And the old data has a smaller field, and no [SII].
You're cranking them up lately. Gorgeous field. I really like the top part coming down on the central bok swith the cluster in the middle, all those filaments look great. Very 3D. 
