astra.contrib.thecannon.continuum

Continuum-normalization.

Module Contents

Functions

sines_and_cosines(dispersion, flux, ivar, continuum_pixels, L=1400, order=3, regions=None, fill_value=1.0, **kwargs) Fit the flux values of pre-defined continuum pixels using a sum of sine and
normalize(dispersion, flux, ivar, continuum_regions=None, L=1400, order=3, regions=([3000, 10000], [15090, 15822], [15823, 16451], [16452, 16971]), fill_value=1.0, **kwargs) Pseudo-continuum-normalize the flux using a defined set of continuum pixels
astra.contrib.thecannon.continuum.sines_and_cosines(dispersion, flux, ivar, continuum_pixels, L=1400, order=3, regions=None, fill_value=1.0, **kwargs)

Fit the flux values of pre-defined continuum pixels using a sum of sine and cosine functions.

Parameters:
  • dispersion – The dispersion values.
  • flux – The flux values for all pixels, as they correspond to the dispersion array.
  • ivar – The inverse variances for all pixels, as they correspond to the dispersion array.
  • continuum_pixels – A mask that selects pixels that should be considered as ‘continuum’.
  • L – [optional] The length scale for the sines and cosines.
  • order – [optional] The number of sine/cosine functions to use in the fit.
  • regions –

    [optional] Specify sections of the spectra that should be fitted separately in each star. This may be due to gaps between CCDs, or some other physically- motivated reason. These values should be specified in the same units as the dispersion, and should be given as a list of [(start, end), ...] values. For example, APOGEE spectra have gaps near the following wavelengths which could be used as regions:

    >> regions = ([15090, 15822], [15823, 16451], [16452, 16971])

  • fill_value – [optional] The continuum value to use for when no continuum was calculated for that particular pixel (e.g., the pixel is outside of the regions).
  • full_output – [optional] If set as True, then a metadata dictionary will also be returned.
Returns:

The continuum values for all pixels, and a dictionary that contains metadata about the fit.
astra.contrib.thecannon.continuum.normalize(dispersion, flux, ivar, continuum_regions=None, L=1400, order=3, regions=([3000, 10000], [15090, 15822], [15823, 16451], [16452, 16971]), fill_value=1.0, **kwargs)

Pseudo-continuum-normalize the flux using a defined set of continuum pixels and a sum of sine and cosine functions.

Parameters:
  • dispersion – The dispersion values.
  • flux – The flux values for all pixels, as they correspond to the dispersion array.
  • ivar – The inverse variances for all pixels, as they correspond to the dispersion array.
  • continuum_regions – [optional] A list of two-length tuples that describe the start and end of regions that should be treated as continuum.
  • L – [optional] The length scale for the sines and cosines.
  • order – [optional] The number of sine/cosine functions to use in the fit.
  • regions –

    [optional] Specify sections of the spectra that should be fitted separately in each star. This may be due to gaps between CCDs, or some other physically- motivated reason. These values should be specified in the same units as the dispersion, and should be given as a list of [(start, end), ...] values. For example, APOGEE spectra have gaps near the following wavelengths which could be used as regions:

    >> regions = ([15090, 15822], [15823, 16451], [16452, 16971])

  • fill_value – [optional] The continuum value to use for when no continuum was calculated for that particular pixel (e.g., the pixel is outside of the regions).
  • full_output – [optional] If set as True, then a metadata dictionary will also be returned.
Returns:

The continuum values for all pixels, and a dictionary that contains metadata about the fit.