Variability Properties (Source Extraction)

This dialog sets Properties for detecting variable objects contained in the list of sources extracted from an image set. This dialog opens from the Post-process page of the Source Extraction Properties. The properties of sources meeting the variability criteria are listed in the Extraction Messages window. This listing includes the amount of their variation, hence you can list the amount of variation for all detected and filtered objects by choosing the None option.

Only sources meeting the variability criteria given below are tabulated in the Messages window.

Variability Properties Properties
None - All Sources	Does not test for variability; includes all objects in the final list of extracted sources. Use this option so that all final sources are listed in the processing summary, including the amount of their variability.
Sigma Threshold	Includes objects varying more than a specified number of sigma's. This value specifies the number of sigma's, for example, "3" for detection of sources varying by more than 3 times their internal sigma value. The internal variation is computed using error estimates produced by the Aperture Photometry Post-process step.
Maximum Deviation	Includes objects varying more than a specified maximum deviation. To pass the variability test, the computed variation is compared with the specified deviation.

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