PixInsight Forum (historical)

PixInsight => Wish List => Topic started by: jeffweiss9 on 2019 August 05 17:20:06

Title: Correction for PCC for color absorption due to dust in our galaxy.
Post by: jeffweiss9 on 2019 August 05 17:20:06

Juan, et al-
There is an interesting discussion summarized on ABIN at:

https://www.astrobin.com/419296/

about whether PCC (or a new process or script) could take these effects into account relatively accurately, rather than resorting to the old CC and guessing at the blue extinction.
I suggested on that ABIN link that I thought, but don't have any reference, that professional astronomers have decent estimates of reddening due to absorption due to the dust in our galaxy for many, if not all, view directions from our galaxy.  If such a map exists, perhaps PI (or a PI scripter) could develop a new Color Correction script (or process) that corrected the colors by the amount of extinction in each RGB band.

Any thoughts about this?
CS/Jeff

Title: Re: Correction for PCC for color absorption due to dust in our galaxy.
Post by: KuriousGeorge on 2019 August 05 17:46:24

I think this would be an amazing feature, especially if it could be turned on and off. It would help unhide many hidden objects.   :surprised:

Title: Re: Correction for PCC for color absorption due to dust in our galaxy.
Post by: Juan Conejero on 2019 August 06 01:40:02

This is already "done". See two examples with Omega Centauri by Rick Stevenson:

PCC, average spiral galaxy white reference:
https://www.astrobin.com/299315/E/

PCC, average spiral galaxy white reference + correction for galactic dust extinction:
https://www.astrobin.com/299315/F/

Vicent Peris already designed the algorithm for galactic extinction correction, and we have been working on the implementation (which is not trivial—one cannot just apply mapped extinction values pixel by pixel). The main problem here is having a set of reasonably reliable observational data. I plan on using Gaia DR2, which provides galactic dust extinction data (https://www.cosmos.esa.int/web/gaia/gaiadr2_cu8) for about 88 million stars.

So you can count on this feature implemented in a future release of the PCC tool. The algorithmic part and its implementation are already designed. I just have to build a suitable database from original Gaia DR2 data files, along with the required code to access it efficiently.

Title: Re: Correction for PCC for color absorption due to dust in our galaxy.
Post by: KuriousGeorge on 2019 August 06 07:36:58

Thank you Juan! This will be an amazing enhancement to PCC.

Title: Re: Correction for PCC for color absorption due to dust in our galaxy.
Post by: jeffweiss9 on 2019 August 06 21:21:27

Terrific, Juan-
That's a great new capability, when available.
Thanks.
CS/Jeff