Total detection noise measurements from sample-to-sample prescan variations mapped by colour for the Gaia focal plane science devices (strip 2 = SM1; strip 3 = SM2; strip 4 = AF1; strips 5–12 = AF2–AF9; strip 13 = BP; strip 14 = RP; strips 15–17 = RVS in high resolution mode). Only one device (AF2 in row 5) is outside the design requirement by around 10%; all other devices are well within their respective design requirement. Not shown are Basic Angle Monitor and Wave Front Sensor devices in strip 1 and in strip 12 in row 4.