[RCC] NGC488

Request for feedback Galaxy NGC488 NGC Objects Deep Sky
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Paul Ecclestone-Brown avatar
Paul Ecclestone-Brown avatar
OK this has been the most challenging galaxy shot I have attempted to process - tbh I am not really happy with it so would appreciate tips on how to get this further - more blue, less red and a bit more oomph other than more data / bigger mirror

The target is faint and very small and subtly detailed

acquisition on the excellent pier 1 of roboscopes in Extremadura.  One of @Peter Shah 's specials a 656 imaging 10in CDK.


My process - carefuil calibration and rejectioon of subs.  followed by linear fit rejction during stacking in PI

linear fit of rgb channels, removal of gradient,  rgb combination, stretch using masked stretch and removal of stars using star exterminator. (saving star layer) green removal using sncr (only at this point to get full spectrum on diffraction spikes)

c and saturation curves enhancement


luminance - psf evaluation and then removal of stars using starexterminator.  very gentle deconvolution using psf

stretch using masked stretch - local normalisation and K curve adjustment to increase contrast

(feeling dirty now) slight sharpness nudge in Topaz

LRGB recombination 

add back stars  using~((~stars) * (~starless))

slight histogram teaks and save



Rings within rings - NGC488
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Andy Wray avatar
Andy Wray avatar
Something looks wrong with the red data;  it's very blurry with no detail compared to green and blue.  Almost like it was either shot through clouds or with lots of dew.  N.B.  I'm not that experienced when it comes to astrophotography, but it just looks wrong to me.
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Jeffbax Velocicaptor avatar
Jeffbax Velocicaptor avatar
Hi. This image is very nice. But something disturbing about the red layer. Dominating the RGB channels and fading some details.

The background is a bit too dark IMO.


Just my 2 cents

CS 

JF
kuechlew avatar
kuechlew avatar
Very nice and deep image. You may try the GHS script by https://ghsastro.co.uk/ for stretching. It provides a lot of control at the price of a bit of a learning curve. Should help you to achieve your aims of "more blue, less red and a bit more oomph" with smart choices of the symmetry points for the individual color channels. The website contains some demo videos. It's well supported here at astrobin by Dave Payne (David Payne's gallery - AstroBin) and  Mike Cranfield (Mike Cranfield's gallery - AstroBin)  e.g. in this thread: Pixinsight image stretching – GHS Version 2 - AstroBin

Good luck and clear skies
Wolfgang
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Paul Ecclestone-Brown avatar
Paul Ecclestone-Brown avatar
Yep the red layer was a bit disturbing -  I was a bit heavy handed on adjusting the CIE c curve - I was more gegle with that and a better image emerged - thanks for your advice
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