The Cooperative Institute for Research in Environmental Sciences (CIRES).
The study of geomagnetism is one of the oldest of the geophysical sciences. The geomagnetic fields have been observed and used from ancient times. Modern uses of geomagnetic data include navigation and mineral exploration. The National Centers for Environmental Information (NCEI) develops and distributes models of the geomagnetic field and maintains archives of geomagnetic data to further the understanding of Earth magnetism and the Sun-Earth environment.
NOAA has updated the magnetic calculator(s). The older style calculators will continue to be available for some time through the CIRES Geomagnetism research site. Follow the link for access to the backup calculators.