Data for before (black) and after (red) the shock on 2002 July 17. The particles centered around 1 keV are data observations from SWEPAM, while the second group of data (*) are observations from EPAM. Both instruments are on ACE. The line through the EPAM data is the power-law fit to observations immediately following the shock encounter. The power-law fit and uncertainty are reported in the plot as γ.