modelBC03

modelBC03 is a python module to fit Brussel and Charlotte stellar population synthesis model to spectrum.

import modelBC03

m = modelBC03.modelBC03()

m.fit(wavelengths, spectrum)

m.predict(wavelengths2)

fitting

It uses generalized linear models from sklearn -- either Lasso or Ridge regression. It is recommanded to use the Lasso regression option, which finds a linear combination of a small number of templates to fit the data. It is reasonably fast.

extinction

modelBC03 can incorporate extinction but it is not well tested. There are three options: 'none', 'linear', 'calzetti00'. To determine the amount of extinction, it first tries to fit only the high frequency (absorption line) part of the spectrum to predict a dereddened spectrum. It takes the ratio between the dereddenedd and the original spectrum and fits a extinction curve to it. This best fit extinction curve is then applied to the templates.

emission lines

It does not handle emission lines, please mask them before fitting.

to link to model files

Please download the spectrum library from the following repo. SDSS credentials maybe needed.

svn checkout https://svn.sdss.org/data/sdss/stellarpopmodels/tags/v1_0_2/ stellar_population_models

Please set the directory path to the spectra_bc03_downgraded/ folder.

m = modelBC03.modelBC03(directory='path_to/spectra_bc03_downgraded/')

Alternatively use the environment variable MODELBC03_DIR. For example, in ~/.bashrc file, add line:

export MODELBC03_DIR='path_to/spectra_bc03_downgraded/'

installing

The recommended method is to clone or download the source code and add the path to your .bashrc..