Full frame count rates in the EPIC PN, MOS1, and MOS2 chips vs. elapsed exposure time for the program stars HD 19445, HD 25329 and HD 140283. The PN full frames rates are shown in the top row of panels. Usually times with rates greater than 3.0 counts s⁻¹ were filtered out. The lower row of panels plots the MOS1 and MOS2 rates as red and black lines. In the case of the HD 19445 and HD 140283 exposures with this pair of chips, times at which the count rate was greater than 0.4 counts s⁻¹ were usually filtered out. The exposures of HD 25329 are characterized by high and time-variable background counts.