The Great Magnetic Storm of 19 December 1980: Observations at L=4

The great magnetic storm of 19 December 1980 occurred during a major rocket and balloon campaign at Siple Station, Antarctica. A balloon flight was conducted during the main phase of the storm. The balloon payload measured the electric field and bremBtrahlung X ray precipitation. The balloon data and associated ground-based data from around the world contain six complementary lines of evidence that the dayside auroral oval expanded to an invariant latitude