Skip to content
New issue

Have a question about this project? Sign up for a free GitHub account to open an issue and contact its maintainers and the community.

By clicking “Sign up for GitHub”, you agree to our terms of service and privacy statement. We’ll occasionally send you account related emails.

Already on GitHub? Sign in to your account

sigma_clip in sky annulus #65

Open
juliotux opened this issue Sep 3, 2018 · 3 comments
Open

sigma_clip in sky annulus #65

juliotux opened this issue Sep 3, 2018 · 3 comments

Comments

@juliotux
Copy link
Contributor

juliotux commented Sep 3, 2018

Almost all the photometric codes perform some type of sigma clip in sky annulus before calculate the sum. SExtractor also make it, but SEP miss this feature. Some background subtraction problems appear.

@kbarbary
Copy link
Owner

kbarbary commented Sep 9, 2018

This would be a welcome addition, but it's not trivial to implement.

@juliotux
Copy link
Contributor Author

juliotux commented Sep 9, 2018

In reality, the SExtractor sky algorithm do not include the sky annulus sum. It computes the sky value in a independent way, by the 2.5median-1.5mean value. After finish my PhD thesis in this week I can study how to implement this and create a pull request.

@kbarbary
Copy link
Owner

The SExtractor global background algorithm certianly does use the 2.5 * median - 1.5 * mean method. (As does SEP.Background, which should give identical results to SExtractor global background.) I thought the SExtractor local background annulus (which is actually a "box" annulus) does not use this, but I might be wrong.

Sign up for free to join this conversation on GitHub. Already have an account? Sign in to comment
Labels
None yet
Projects
None yet
Development

No branches or pull requests

2 participants