Last night we added another 6.5 hours of luminance to our previous (2016) mammoth run on NGC 4945. The seeing was a little better, and the final stack was a little sharper for it.
We previously showed the colour "as perceived", a drab orange-red, due to intervening Milky Way dust.
This time, (as others have done before) we tried for a more "colour agnostic" version, to show how it might seem if we had a slightly clearer view. The 11 hours per channel was enough to permit this.
Edit: "The colour agnostic" approach:
(1) Set the black point to the foothill of the histogram in each channel, so that the darkest parts of the image show as black, but with no loss of information.
(2) Select an area of special interest (in this case, the galaxy), and adjust the gain so that the galaxy is, on average, grey. That is to say, the red, the green, and the blue all cancel.
(3) Crank up the saturation, to show important differences, in this case, showing that some areas are very cool (now orange) and plausibly of great antiquity, some areas are very hot (now blue) and therefore very young.
Rather prettier, we think.
Despite the thick dust, one can just, just barely, make out a rather fine distant face-on spiral about half-way to top right, and three other galaxies far, far away.
Aspen GC16M and then FLI PL16803 on 20" PlaneWave. Luminance 18.5 hrs, RGB 11 hrs each.
That's a mammoth effort guys; respect! There's a cool little spiral at about 20% in from the left, and 60% down from the top. And what's that around the star in the bottom left, is it an irregular galaxy in the background?
That's a mammoth effort guys; respect! There's a cool little spiral at about 20% in from the left, and 60% down from the top. And what's that around the star in the bottom left, is it an irregular galaxy in the background?
Thanks Lee. It's pleasing to see any background galaxies at all in amongst the Milky Way stars and dust. Yes, it does look like a tiny baby NGC 55 hiding down there.
Quote:
Originally Posted by DavidTrap
Magnificent!
DT
Thanks David!
Quote:
Originally Posted by Retrograde
Amazing depth & lovely colours.
A gorgeous image.
Many thanks Pete. Hope we didn't overdo the colours, but there's an APOD where they went even further, so there's a precedent.
Quote:
Originally Posted by h0ughy
Detail and colours are very satisfying. Awesome result
Very nice. I had a bit of a scan around the image and I think I can see at least 6 other galaxies in there (plus at least 3 more that are strong maybes).
Very nice. I had a bit of a scan around the image and I think I can see at least 6 other galaxies in there (plus at least 3 more that are strong maybes).
Thanks Chris. Our highly experienced galaxy spotter (Mike after 3 coffees) looking at the TIFF on the 4K monitor found sixty three.
So very smooth. Great field and colors. Love that little side-on hiding behind the star at 7 o'clock. Lots of interesting faint fuzzies in the field too. One for the poolroom.
So very smooth. Great field and colors. Love that little side-on hiding behind the star at 7 o'clock. Lots of interesting faint fuzzies in the field too. One for the poolroom.
Wow, 50 hours, that's a lot. I did some imaging of this one last night on a CDK17. Its a reasonably bright galaxy. I like the way you got rid of the yellowish colour gradient you normally see with this one. Very clever.
Wow, 50 hours, that's a lot. I did some imaging of this one last night on a CDK17. Its a reasonably bright galaxy. I like the way you got rid of the yellowish colour gradient you normally see with this one. Very clever.
Greg.
Thanks Greg! So often we go back to our archives and think, "Oh dear, we've come a long way since then", but this time, we were actually able to use, and add to, the data from yesteryear.
A huge effort delivering a compelling, smooth and detailed image M&T!
But, but to be honest, I'm not sure about attempting to remove the effect of the intervening dust. How did you know how to calibrate out that effect? G2V calibration? Having said that a G2V star on the other side of the dust would almost certainly not be visible! In any case I'd actually prefer the warm orange and yellow tones imparted by the dust (cf my old 2009 rendition here).
So very smooth. Great field and colors. Love that little side-on hiding behind the star at 7 o'clock. Lots of interesting faint fuzzies in the field too. One for the poolroom. 
