First Star Color Ca...
 
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First Star Color Calibration


 momo
(@mo-mo)
Red Giant Customer
Joined: 1 year ago
Posts: 121
Topic starter  

Hello

I used the Star Collar Calibration Tool for the first time. The image is at that time.
I am not understood by the following point. I'm glad if I get advice from someone.

1. What are the graphs propose to me?
I understand that it represents the distribution of stars

2. What I make a basis of adjustment of BLUE-RED SLIDER, B-G VERSUS G-R, B-R VERSUS G-R ?

 Thank you

2

 


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(@vincent-mod)
Universe Admin
Joined: 6 years ago
Posts: 5206
 

I would advice to have a look at these video's by Christian Sasse: https://www.astropixelprocessor.com/complete-lrgb-tutorial-of-ngc292-the-small-magellanic-cloud-by-christian-sasse-itelescope-net-new-version-app-1-081/

Bit further down he works with this tool. It basically shows you the distribution of detected stars and their color profile, it assumes stars are black bodies which will have a very well defined profile. You would want to see the stars following this black body model well, which is diagonally in the graphs and you can tweak this using the sliders a bit, like the slope etc.

One caveat though is that this only works well with broad spectrum data, not narrowband.


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 momo
(@mo-mo)
Red Giant Customer
Joined: 1 year ago
Posts: 121
Topic starter  

@vincent-mod

Hello Vincent

I had a look at these video's by Christian Sasse.

I understood that the graphs do not just propose a proper color, but simply shows the color distribution of the stars.
Does I make the stars red or blue are decided by my subjectivity or sensitivity?

The graphs change by changing Slope, but how can I determine if the Slope value is appropriate or not?

Thank you

 


ReplyQuote
(@vincent-mod)
Universe Admin
Joined: 6 years ago
Posts: 5206
 

Yes it's color distribution and you expect stars to be more or less on the line of the model, less blue stars on the bottom left, more red on the top right. These are known spectra and not subjective. If your stars are not behaving like that in your image, that means you either used filters or other things that change the spectra observed. This is why narrowband data doesn't produce this known characteristic and therefore the tool can't really be used for an accurate correction. When you do have broadband data, then you can. You can change the slopes a bit so that the distribution of the stars follows the black body model a bit better. You can see Christian doing this at about the 16:00 mark.


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 momo
(@mo-mo)
Red Giant Customer
Joined: 1 year ago
Posts: 121
Topic starter  

My image is a broadband, so I think it is suitable for this tool.

"You Can Change The Slopes A Bit So That The Distribution of the Stars Follows The Black Body Model A Bit Better."

I try to change the slope so that.

Thank you


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