Magnetic perturbations and correlations during the first 8 UT hours of April 5, 2010 at Athabasca. (a) SMALL fluxgate magnetometer data. Time scale is in hours with subdivisions 10 minutes. Vertical scale is marked at 100 nT intervals. The X component is shown in black, Y component in red, and Z component in blue. (b), (c), (d) correlation of SMALL data and roughly calibrated NPM data, nT on both axes indicated in 100 nT intervals. (e) NPM results after calibration based on SMALL data, plotted as in (a).