CCD performance in terms of the video-chain total detection noise as measured from the second of the two prescan samples available for each CCD, but summarised via a mean and standard deviation over all CCDs grouped by instrument.
|Instrument||Mean gain||Total detection noise per sample|
|SM||0.2569||13.0||10.829 ± 0.494||2.782 ± 0.127|
|AF1||0.2583||10.0||8.556 ± 0.438||2.210 ± 0.113|
|AF2–9||0.2578||6.5||4.326 ± 0.648||1.115 ± 0.167|
|BP||0.2464||6.5||5.170 ± 0.362||1.274 ± 0.089|
|RP||0.2484||6.5||4.752 ± 0.175||1.180 ± 0.043|
|RVS-HR||1.7700||6.0||3.272 ± 0.155||5.791 ± 0.274|
|RVS-LR||1.8185||4.0||2.907 ± 0.177||5.286 ± 0.322|
Notes. The analysis period used was July 2014 to November 2016 and covers the entire science operational period of DR2. Measurements are given in analogue-to-digital units (ADU) and electrons using the gain measurements quoted in the second column, where the gain was measured on-ground prior to launch (this cannot be measured in-orbit owing to the non-availability of flat field illumination). All instruments are statistically well within the design requirement quoted in the third column. For the RVS instrument, the measurements are subdivided into high-resolution (HR) and low-resolution (LR) modes where the latter samples are hardware binned on-chip by 3 pixels in the along-scan direction. This observing mode was used only briefly at the start of the mission (Cropper et al. 2018). Note the larger gain in the RVS: this is the main contributor to the greater impact of the bias non-uniformity in this instrument.