Distribution of burst-mode data hours per month for 2014 and 2018 to 2023. The rolling 28-day mean altitude of each craft for this period is shown by the solid line for Swarm Bravo (B) and the dashed converging lines for Alpha (A) and Charlie (C). The open circle at 05-Nov-2014 indicates when Swarm Charlie stopped producing ASM data and the dashed vertical line indicates a break in the data from 2015 to 2017.