NGC4565 Needle Galaxy

[don4l]

This is my first attempt at using techniques that I have picked up here at SGL.  It is also my first LRGB where I feel that I've managed to overcome the dreadful light pollution.  I had more or less retired to almost exclusive use of Narrowband imaging.

Any comments or advice would be very welcome.  I should say that I have severe doubts about the brightness and contrast of my laptop screen, so I would very much appreciate comments on those!  The stars also look green to me, but adjusting the green channel doesn't seem to fix the problem.

Equipment:  FSQ105ED with Extender Q,   STL6303, EQ6 pro.

L = 210m, R = 27m, G = 123m, B = 75m

Calibrated in CCDStack, processed with the Gimp.

In the past I have really struggled with light pollution in the green data, so I ended up taking far more than I needed.  It wasn't as bad as I expected - I suspect that the street lights have been changed since 2010 when I last tried LRGB.

 

 

[Demonperformer]

Very nice. I do like seeing galaxies "in context". Several small ones there as well.

[don4l]

4 hours ago, Demonperformer said:

Very nice. I do like seeing galaxies "in context". Several small ones there as well.

Thank you.

Could I ask how it looks on your screen?

I process the images  on a laptop, and it looks fine there.  On my work PC, the background looks pitch black, and the galaxy looks a deep reddish-brown.  I have no idea if either PC is showing it the way most people are seeing it.

[Demonperformer]

The galaxy is probably redder than I would have done it.

Not sure if it will help a lot, but I've attached a crop of the screenprint with the pixel colour values that I get for an average (if there is such a thing) pixel in the galaxy itself. If you load up a drawing prog and create an image to match those values, it may give you some idea of how the colour compares with what you were expecting?

[don4l]

9 hours ago, Demonperformer said:

The galaxy is probably redder than I would have done it.

Not sure if it will help a lot, but I've attached a crop of the screenprint with the pixel colour values that I get for an average (if there is such a thing) pixel in the galaxy itself. If you load up a drawing prog and create an image to match those values, it may give you some idea of how the colour compares with what you were expecting?

Thanks for the feedback.  I've tried to recalibrate my laptop screen, although I'm still not confident that it is right!

 

Here is another version that is much less "red".  I'm hoping that the background is dark grey, but not black.

I'd also be very grateful to know if there is a green cast to the bottom half of the image.  I can see it in Windows Picture Viewer, but not in my graphics SW (Gimp).

 

 

 

[Demonperformer]

I think the galaxies are a better colour in this one. Comparing individual pixels between the two versions each colour has an increase in the second version R+5%, G+28%, B+22%, and I think this produces a better balance.

I have measured some background pixels in the second image, and there do appear to be two trends. In percentage terms, the green increases from about 25% to just over 30% moving down the picture and the red increases from about 30% to just under 35% moving left to right. So it is about the same increase and, to me, the red on the righthand side is particularly noticeable. My guess would be that that is the direction of your LP?

 

[SIDO]

Very sharp, nice job...

[don4l]

1 hour ago, Demonperformer said:

I think the galaxies are a better colour in this one. Comparing individual pixels between the two versions each colour has an increase in the second version R+5%, G+28%, B+22%, and I think this produces a better balance.

I have measured some background pixels in the second image, and there do appear to be two trends. In percentage terms, the green increases from about 25% to just over 30% moving down the picture and the red increases from about 30% to just under 35% moving left to right. So it is about the same increase and, to me, the red on the righthand side is particularly noticeable. My guess would be that that is the direction of your LP?

 

Thank you very much!

I've recalibrated my screen, and I can see what you describe.  So, hopefully, my images will look a bit better in the future.