Utility Functions

Utility functions for the satkit package

API Reference

Utility functions for SatKit

satkit.utils.builddate()

Return build date of this satkit library as a string

Returns:

Build date of this satkit library

Return type:

str

satkit.utils.datadir()

Return directory currently used to hold necessary data files for the directory

Data directory is 1st of following directories search that contains the data files listed in “update_datafiles”

  • MacOS:

    1. Directory pointed to by SATKIT_DATA environment variable

    2. $DYLIB/satkit-data where $DYLIB is location of compiled python satkit library

    3. $HOME/LIBRARY/Application\ Support/satkit-data

    4. $HOME/.astro-data

    5. $HOME

    6. /usr/share/astro-data

    7. /Library/Application\ Support/astro-data

  • Linux:

    1. Directory pointed to by SATKIT_DATA environment variable

    2. $DYLIB/satkit-data where $DYLIB is location of compiled python satkit library

    3. $HOME/.astro-data

    4. $HOME

    5. /usr/share/astro-data

  • Windows:

    1. Directory pointed to by SATKIT_DATA environment variable

    2. $DYLIB/satkit-data where $DYLIB is location of compiled python satkit library

    3. $HOME/.astro-data

    4. $HOME

satkit.utils.githash()

Return git hash of this satkit build

Returns:

Git hash of this satkit build

Return type:

str

satkit.utils.update_datafiles(**kwargs)

Download & store data files needed for “satkit” computations

Keyword Arguments:

  • overwrite (bool) – Download and overwrite files if they already exist

  • dir (string) – Target directory for files. Uses existing data directory if not specified. (see “datadir” function)

Notes

  • Files include:

    • EGM96.gfc : EGM-96 Gravity Model Coefficients

    • JGM3.gfc : JGM-3 Gravity Model Coefficients

    • JGM2.gfc : JGM-2 Gravity Model Coefficients

    • ITU_GRACE16.gfc : ITU Grace 16 Gravity

    • tab5.2a.txt : Coefficients for GCRS to GCRF conversion

    • tab5.2b.txt : Coefficients for GCRS to GCRF conversion

    • tab5.2d.txt : Coefficients for GCRS to GCRF conversion

    • SW-ALL.csv : Space weather data, updated daily

    • leap-seconds.txt : Leap seconds (UTC vs TAI)

    • EOP-All.csv : Earth orientation parameters, updated daily

    • linux_p1550p2650.440 : JPL Ephemeris version 440 (~ 100 MB)

  • The space weather and earth orientation parameters files are updated daily and will always be downloaded regardless of the overwrite flag