calculate_red_blue_asymmetry

irispy.utils.red_blue.calculate_red_blue_asymmetry(

cube,

*,

rest_wavelength=None,

velocity_range=<Quantity [ 50.,

150.] km / s>,

dv=<Quantity 10. km / s>,

continuum_windows=None,

degree=3,

min_intensity=None,

saturation_limit=None,

return_profiles=True,

)

Calculate red-blue asymmetry maps from a spectrogram cube.

The asymmetry is computed for each spatial pixel as \((I_R - I_B) / I_p\), where I_R and I_B are mean intensities in matching red and blue velocity ranges and I_p is the interpolated peak intensity.

Parameters:

• cube (irispy.spectrograph.SpectrogramCube) – Input spectrogram cube.

• rest_wavelength (astropy.units.Quantity, optional) – Rest wavelength used to convert the spectral axis to Doppler velocity. If omitted, read from cube.meta.rest_wavelength (requires an SGMeta instance with a TWAVE<n> FITS keyword).

• velocity_range (astropy.units.Quantity, optional) – Two positive velocities defining the wing range to average.

• dv (astropy.units.Quantity, optional) – Velocity spacing for the interpolated profile.

• continuum_windows (astropy.units.Quantity, optional) – One or more wavelength windows used to estimate and subtract a continuum.

• degree (int, optional) – Spline degree for scipy.interpolate.make_interp_spline.

• min_intensity (float or astropy.units.Quantity, optional) – Minimum peak intensity required for a pixel to be processed. Pixels below this threshold are assigned quality flag LOW_SIGNAL.

• saturation_limit (float or astropy.units.Quantity, optional) – Maximum allowed peak intensity. Pixels above this value are assigned quality flag SATURATED.

• return_profiles (bool, optional) – If True, include 3D "observed_profile" and "interpolated_profile" cubes in the output.

Returns:

Always contains "red_blue_asymmetry" and "quality" 2D maps. "red_blue_asymmetry_error" is added when the input cube has uncertainty. "observed_profile" and "interpolated_profile" 3D cubes are added when return_profiles=True. The interpolated profile velocity axis is peak-centred; the observed profile velocity axis is relative to rest_wavelength.

Return type:

irispy.spectrograph.RasterCollection