output chi map as FITS extension 6

glenco / lensed

forward reconstruction of lenses and sources from strong lensing observations

http://glenco.github.io/lensed/

MIT License

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output chi map as FITS extension 6 #244

Closed ntessore closed 8 years ago

ntessore commented 8 years ago

This PR outputs a map of the chi-values chi = sqrt(chi2) = |image - model|/sigma for each pixel as FITS extension 6 (name CHI).

This is useful as it is a statistically meaningful "relative error" map. Because each pixel follows a chi distribution with one degree of freedom, plotting the chi map with a scale [0, 2.57585] for example shows where residual pixels are excluded at the 99% confidence level.

rbmetcalf commented 8 years ago

Looks cool.