PhotutilsAperturePhotometry#

class prose.blocks.PhotutilsAperturePhotometry(apertures=None, r_in=5, r_out=8, scale=True, sigclip=2.0, **kwargs)#

Aperture photometry using the CircularAperture and CircularAnnulus of photutils with a wide range of apertures. By default annulus goes from 5 fwhm to 8 fwhm and apertures from 0.1 to 10 times the fwhm with 0.25 steps (leading to 40 apertures).

The error (e.g. in ADU) is then computed following:

\[\sigma = \sqrt{S + (A_p + \frac{A_p}{A_n})(b + r^2 + \frac{gain^2}{2}) + scint }\]
rst/generated/images/aperture_phot.png

with \(S\) the flux (ADU) within an aperture of area \(A_p\), \(b\) the background flux (ADU) within an annulus of area \(A_n\), \(r\) the read-noise (ADU) and \(scint\) is a scintillation term expressed as:

\[scint = \frac{S_fd^{2/3} airmass^{7/4} h}{16T}\]

with \(S_f\) a scintillation factor, \(d\) the aperture diameter (m), \(h\) the altitude (m) and \(T\) the exposure time.

The positions of individual stars are taken from Image.stars_coords so one of the detection block should be used, placed before this one.

For more details check https://photutils.readthedocs.io/en/stable/aperture.html

write

  • Image.stars_coords

  • Image.apertures_area

  • Image.sky

  • Image.fluxes

  • Image.annulus_area

  • Image.annulus_rin

  • Image.annulus_rout

  • Image.apertures_radii

  • Image.fluxes

modify data

Parameters:

  • apertures (ndarray or list, optional) – apertures in fraction of fwhm, by default None, i.e. np.arange(0.1, 8, 0.25)

  • r_in (int, optional) – radius of the inner annulus in fraction of fwhm, by default 5

  • r_out (int, optional) – radius of the outer annulus in fraction of fwhm, by default 8

  • scale (bool or float:) – Multiplication factor applied to apertures. - if True: apertures multiplied by image.fwhm, varying for each image - if False: apertures not multiplied - if float: apertures multiplied scale and held fixed for all images