AperturePhotometry PSF Output

[janame]

I've noticed the PSF_SIGMAX and PSF_SIGMAY values in the CSV generated by the AperturePhotometry script don't match the values I get using the DynamicPSF process on the same star.

Looking at the source, at line 2447, I see:
// starIndex, function, circular, status, B, A, cx, cy, sx, sy, theta, beta, mad
referenceStars[starIdx].psf = {
sigmaX: psf[ 8] * 2.354820045 * referenceWindow.metadataWCS.resolution * 3600,
sigmaY: psf[ 9] * 2.354820045 * referenceWindow.metadataWCS.resolution * 3600,
A: psf[ 5],
theta: psf[10],
MAD: psf[12]
};

From this, it looks like what AperturePhotometry is calling sigma should be FWHM (by including the factor of 2.354...).
I don't understand why there is an additional factor of resolution * 3600.

Can anyone clarify what's going on here? @Andres.Pozo @vicent_peris

 

[Mike1485]

I presume the 3600 is converting to seconds?

 

[janame]

Ah, it appears the script is reporting FWHM in arcsec for the sigma values.

I had checked for this previously, but didn't realize the astrometric solution from AperturePhotometry wasn't saved in the image metadata. If I run ImageSolver first, the DynamicPSF FWHM matches the AperturePhotometry sigma results.