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Aperture Properties (Source Extraction)
This dialog sets Properties for the Aperture Photometry measurement. This measurement
is one of the
Post-process options for the
Extract Sources command. As is normal for aperture
photometry, all objects are measured using the same aperture
Properties.
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Background Method
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Specifies the maximum radius, in pixels, for
computing the FWHM.
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Zero Point
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Specifies the photometric zero point magnitude.
This is the magnitude corresponding to 1 detected electron per
second.
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The radius, in pixel units, of the object
measuring aperture.
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The radius, in pixel units, of the inner
background measuring aperture.
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The radius, in pixel units, of the outer
background measuring aperture.
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The ellipticity of the apertures. This is the
value of 1 - b/a, where b is the minor axis and a is
the major axis. Circular apertures have an ellipticity of 0; a
linear aperture has a value of 1. The maximum allowed ellipticity
is 0.999.
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Angle
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The orientation of the major axis of the
apertures, in units of degrees. If the Ellipticity is 0, then the apertures are circular
and the angle has no significance.
Note: If the ellipticity is 0, the Angle control is
disabled.
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Note
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Aperture Photometry gives the best background
estimates when sources are separated by empty background. This is
because the local background used by the measurement samples pixels
lying inside an annulus surrounding the source. The Modal
Brightness Median Brightness background methods do rejection of
non-background pixels but still can give a Biased result when non
background pixels comprise a significant portion (e.g., 10% or
more) of the local background sample.
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Related Topics
Post-process page
Mira Pro x64 User's Guide, Copyright Ⓒ 2023 Mirametrics, Inc. All
Rights Reserved.
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