Datasets

Datasets

pyshtools provides easy access to many research-grade gravity, shape, and magnetic field datasets of the terrestrial planets, moons, and asteroids. To load a dataset, it is only necessary to call the relevant method from the datasets submodule as in these examples:

    hlm = pysh.datasets.Venus.VenusTopo719()  # Venus shape
    clm = pysh.datasets.Earth.EGM2008()  # Earth gravity
    glm = pysh.datasets.Earth.WDMAM2_800()  # Earth magnetic field
    clm = pysh.datasets.Moon.GRGM1200B()  # Gravity of the Moon

When accessing a dataset, the file will first be downloaded from the original source using pooch and then stored in the pyshtools subdirectory of the user’s cache directory (if it had not been done previously). The file hash will be verified to ensure that it has not been modified, and the file will then be used to initialize and return an SHCoeffs, SHGravCoeffs or SHMagCoeffs class instance. In most cases the files are stored in their original form: If they need to be decompressed or unzipped, this is done on the fly when they are used. Only when zip archives contain several files are the files stored in unzipped form.

The coefficients can be read up to a maximum specified degree by providing the optional variable lmax. For some datasets (such as the shape of Mars), several different models of differing resolution exist, and only the smallest file that is necessary based on the user input value of lmax will be downloaded. For IGRF magnetic field coefficients, the year of the output coefficients can be specified by the optional argument year (the default is 2020).

The following is the list of implemented datasets. Additional older or deprecated datasets can be found in the historical module for each body.

Mercury

Venus

Earth

The Moon

Mars

(1) Ceres

(4) Vesta

(16) Psyche

(433) Eros

Jupiter

Io (Jupiter)

Europa (Jupiter)

Ganymede (Jupiter)

Callisto (Jupiter)

Saturn

Titan (Saturn)

Enceladus (Saturn)

Uranus

Neptune