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.
Big one here
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.
Best,
MnT