Source Significance
In the first release of the CSC, detect and flux significance were related, since sources were accepted for inclusion in the catalog if their flux significance exceeded a given threshold.
In CSC 2.1, three separate metrics are used to describe the significance of detection and flux determination.
Detection Significance & Likelihood
The fundamental metric used to decide whether a source is included in CSC 2.1 is the likelihood,
where
The likelihood is closely related to the
probability,
where
detect_significance vs. likelihood
![[Thumbnail image: detect_significance vs. likelihood]](imgs/detsig_vs_lklhd_bgdgt3.thumb.png)
[Version: full-size]
![[Print media version: detect_significance vs. likelihood]](imgs/detsig_vs_lklhd_bgdgt3.png)
detect_significance vs. likelihood
A plot of the detection significance vs. likelihood is shown in this figure.
Flux Significance
Flux significance is a simple estimate of the ratio of the
flux measurement to its average error. The mode of the marginalized probability distribution
for photflux_aper is used as the flux measurement
and the average error,
which are both used to estimate flux significance.
Table Columns
significance, likelihood
The maximum likelihood and flux significance across all stacked observations and energy bands are reported as the master source significance and likelihood.
flux_significance, detect_significance, likelihood
Likelihood, detect significance, and flux significance are reported per band for all sources detected in the valid stack. The likelihood reported is the maximum of the likelihood determined from the MLE fit to all valid stack data, and the likelihoods from each individual observation, per band.
flux_significance, likelihood
Likelihood and flux significance are reported per band for all detected sources that fall in the valid field of view. Likelihoods are computed for each source detection in a stack, from MLE fits to data from all valid observations for the source. Likelihoods from each individual observation are also computed.