Author Topic: Parameters of PSF functions in aperture photometry  (Read 122 times)

Offline joseboschbailach

  • Newcomer
  • Posts: 4
    • View Profile
Parameters of PSF functions in aperture photometry
« on: 2019 February 14 09:39:27 »
Hello. I am using PixInsight for computing and drawing light curves of BL Lacs, quasars and AGNs. I use the SubframeSelector, the AperturePhotometry and DynamicPSF scripts for the task, and the results I have obtained are agree with other observers and surveys. You can select in DynamicPSF script which kind of function you use: Moffat1, gaussian, lorentzian, etc. When the AperturePhotometry generates de csv files with the calculated PSF flux, what is the PSF employed? I do not know what is the PSF used and in the csv file have no clues. I think a good idea could be to do several photometries with several PSF in order to yield the best results. Can I do that?  Best regards.

José Bosch Bailach

Offline pfile

  • PTeam Member
  • PixInsight Jedi Grand Master
  • ********
  • Posts: 4103
    • View Profile
Re: Parameters of PSF functions in aperture photometry
« Reply #1 on: 2019 February 14 10:35:36 »
the source code for AperturePhotometry indicates that Moffat4 is the PSF fitting function used, as far as i can tell.

since it is hardcoded into the script, it would take a bit of work to make the function user selectable. not impossible, but it's probably something you'd have to try on your own and then submit to Juan and/or Andres del Pozo as an update. unless Andres is willing to implement this feature request.

rob

Offline joseboschbailach

  • Newcomer
  • Posts: 4
    • View Profile
Re: Parameters of PSF functions in aperture photometry
« Reply #2 on: 2019 February 15 10:43:51 »
Ok, that's right. I think that Moffat4 is the better function to compute the photometry because this minimize the errors (I am not sure). What about the others PSFs? Obviously, if one takes another PSF the resulting photometry will be different, because the script computes the flux integrating the PSF. I have made a rough estimate using Wolfram Mathematica and integrating several PSFs and the results are very uneven, so, how can I be sure that this PSF (Moffat4) is the correct one? Thanks.

José Bosch Bailach