2.2.2 spase://SMWG/Person/Duff.C.Stewart 2012-06-13T12:34:56.789 Duff C. Stewart National Geomagnetism Program, United States Geological Survey

1711 Illinois Street, Golden, CO 80401-1865 USA

dcstewart@usgs.gov +1 303 273 8485 +1 303 273 8506