Install casacore-data-igrf by entering the following commands in the terminal:
sudo apt update sudo apt install casacore-data-igrf
International Geomagnetic Reference Field data for casacore
This package contains the coefficients for the standard mathematical description of the Earth's main magnetic field that is used widely in studies of the Earth's deep interior, its crust and its ionosphere and magnetosphere. . The data are in a format specific to casacore.