Mahlke+ 2022

Overview

Observables	Reflectance Spectra, Visual Albedo
Wavelength Range	0.45-2.45µm, or any subset of this range
Number of Classes	16
Class Assignment	Probabilistic

Classes

There are 16 classes plus the common placeholder class X for asteroids of either E, M, or P type without albedo information.

Any asteroid classified as B, C, or P type is classified as Ch if the h feature is present. The classes E, M, P (and X) can further carry the feature flags e and k. can further carry the feature flags e and k if the corresponding features are present.

The spectral class templates can be loaded using the classy.taxonomies.mahlke.load_templates() function, which returns a dict containing the classes as keys and the template spectra as values.

Preprocessing

The following preprocessing steps are automatically done when using the classy.Spectrum.classify() method:

• Feature Detection

• Resampling to common wavelength grid

• Log-transform of reflectance (ln) and albedo (log10)

• Normalisation using mixnorm algorithm

The preprocessing does not change the wave and refl attributes of the spectrum.

Classification

The classification results are probabilistic, meaning that the classified spectrum has a certain probability to belong to a given class. These probabilities are accessible via the class_CLASS attributes, where CLASS should be replaced by the respective class letter. The most probable class is assigned to the class_ attribute.

$ classy classify ceres --plot --taxonomy mahlke

>>> import classy
>>> ceres = classy.Spectra(1, source="ECAS")[0] # get ECAS spectrum of (1) Ceres
>>> ceres.classify()  # taxonomy='mahlke' is default
>>> ceres.class_
'C'
>>> ceres.class_C
0.9597002617708775
>>> ceres.class_B
0.03962395712733269