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03. Dependencies

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Shubham edited this page Mar 21, 2022 · 3 revisions

BCPy (v0.4.4) has the following external package dependencies -

  1. astropy version >= 4.0.4
  2. numpy version >=1.17.2
  3. scipy
  4. jplephem
  5. astroquery version >= 0.3.10
  6. pyerfa version >= 1.7.3

When the setup.py file is run during installation of BCPy, setuptools will attempt to find these packages and download / update them if it is unable to do so. The Astropy version requirement imposes a Python 3.x requirement which phases out support to Python 2.x (v0.3 onwards).

Further, these will be first time installations: On importing the package for the first time -

  1. IERS bulletin using the Astropy utility . Updated either when the file is more than 30 days old, or when a date is queried that it does not cover.

On running call_bcpy() for the first time -

  1. Ephemerides from jplephem. The default is set to DE430, this file would be downloaded the first time barycorrpy is run. This ephemeris is about 100MB in size.

  2. Leap Second file (leap_sec.txt) to account for differences between TAI and UTC. This will be accompanied by the creation of an auxiliary file called leapsec_log.txt to check for when the leap second file needs to be updated.

  3. The hip2.dat file is included with the package installation and is the Hipparcos catalogue. It can be used to extract positional information of the star. The Hipparcos catalogue is sourced from Vizier. Though the Hipparcos catalogue data is largely reliable, it should be and verified (especially proper motion) if the star is a binary.

  4. To calculate Earth Orientation Parameters, BCPy uses the gcrs_posvel_from_itrf() function from PINT. This routine is included with the package install.

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