def pseudo_continuum(flux, ivar, wavelength=None, L=50, dr=None):
"""
Pseudo-Continuum normalise a spectrum by dividing by a Gaussian-weighted smoothed spectrum.
:param flux: The observed flux array.
:type flux: ndarray
:param ivar: The inverse variances of the fluxes.
:type ivar: ndarray
:param wavelength: An array of the wavelengths.
:type wavelength: ndarray
:param L: [optional] The width of the Gaussian in pixels.
:type L: int
:param dr: [optional] dara release
:type dr: int
:returns: Continuum normalized flux and flux uncerteinty
:rtype: ndarray
"""
# Partial Credit: https://github.com/chanconrad/slomp/blob/master/lamost.py
if dr is None:
dr = lamost_default_dr(dr)
if wavelength is None:
wavelength = wavelength_solution(dr=dr)
smoothed_spec = smooth_spec(wavelength, flux, ivar, L)
norm_flux = flux / smoothed_spec
norm_ivar = smoothed_spec * ivar * smoothed_spec
bad_pixel = ~np.isfinite(norm_flux)
norm_flux[bad_pixel] = 1.0
norm_ivar[bad_pixel] = 0.0
return norm_flux, norm_ivar
def wavelength_solution(dr=None):
"""
To return wavelegnth_solution
:param dr: data release
:type dr: Union(int, NoneType)
:return: wavelength solution array
:rtype: ndarray
:History: 2018-Mar-15 - Written - Henry Leung (University of Toronto)
"""
lamost_default_dr(dr=dr)
# delibreately add 1e-5 to prevent numpy to generate an extra element
lamost_wavegrid = 10. ** np.arange(3.5682, 3.5682 - 1e-5 + 3909 * 10. ** -4., 10. ** -4.)
return lamost_wavegrid
