The Fitting window gives access to different fitting utilities.
They all work by selecting in the main VOSpec display window the region in
which we are interested in performing the algorithm (drag right button of mouse
over the spectrum region on which the fitting algorithm shall be run) and then
clicking in the "Generate" button.
Current fitting algorithms
are the following:
Black Body Fitting
TSAP Best Fit
Fits a selected Spectral Energy Distribution to a theoretical model (TSAP service) using
a modified version of the iterative Levenberg-Marquardt Chi-square minimization
algorithm. Both the SED and the theoretical models are not described by continuous
functions. SSA and TSAP servers offer a grid of spectra and theoretical models depending
on several parameters respectively. Therefore, the Chi-square function that the Best Fit
must minimize is a discrete function and the Levenberg-Marquardt method is modified for
the discrete case.
To use the TSAP Best Fit, firstly choose the TSAP Service you wish to fit your selected
Then choose the initial starting parameters for the model:
Once the best fit model has been found, the chi value and best fit parameters are shown
in the Fitting Window:
Finally, the user can choose to load and view the best fit model. The spectra used to
find the best fit are also displayed:
Fits selected part of a
spectrum to a n-grade polynomial using Least Squares fitting method.
Black Body Fitting
Fits selected part of the
spectrum to a black-body continuum spectrum using Levenberg Marquardt
Chi-Square minimization algorithm
Gaussian, Lorentzian and Voight profiles
Fit selected part of the
spectrum to a Gaussian, Lorentzian or Voight profile using Levenberg-Marquardt
Chi-square minimization algorithm.
In the fitting window we can
check the resulting function parameters and the Pearson’s Chi-square value:
considered flux values
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