Hi everyone,
I want to extract the spectrum of one galaxy. But I don't know 'exttype=point or extend'.
If anyone could tell me, I'll appreciate for that. Thank you!
Best wishes,
Dawei Li
exttype
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JeremySanders
- Posts: 28
- Joined: Mon Jun 28, 2021 7:24 am
Re: exttype
Hi Dawei Li
The exttype is used to account for flux which is lost outside the extraction region you give, and to account for the variation of the vignetting across the source. Ideally the source model (given by exttype) should describe the shape of your source. If the X-ray emission of your galaxy is compact and smaller than the PSF, like a point source, then a point source type is fine. However, if it is bigger than the PSF then you should choose a model which better describes the shape - you can choose one of the models given or supply a fits image with a model describing the source (note that the PSF correction doesn't work for a FITS image model).
Hope that helps
Jeremy
The exttype is used to account for flux which is lost outside the extraction region you give, and to account for the variation of the vignetting across the source. Ideally the source model (given by exttype) should describe the shape of your source. If the X-ray emission of your galaxy is compact and smaller than the PSF, like a point source, then a point source type is fine. However, if it is bigger than the PSF then you should choose a model which better describes the shape - you can choose one of the models given or supply a fits image with a model describing the source (note that the PSF correction doesn't work for a FITS image model).
Hope that helps
Jeremy
Re: exttype
Hi Jeremy,
Your suggestion is very helpful. Thank you very much!
Best regards,
Dawei
Your suggestion is very helpful. Thank you very much!
Best regards,
Dawei