Overview

Images of the full well depth over the two UVIS detectors are shown below (Fig 5 from ISR 2010-10). The WFC3 CCDs show about 10% variation over each CCD ranging from 63-71 K electrons on UVIS1 and 67-72 K electrons on UVIS2. The onset of saturation is taken to be the level at which charge spilling along columns first starts and provides the definition of full well depth.

Fig5
The distribution of full well depth for UVIS1 (top) and UVIS2 (bottom) taken to be the number of electrons at which charge spilling just starts to set in for point sources. Local values derived for 313 stars have been smoothed with a Gaussian of width 400 pixels to produce this map.

ISR 2010-10 provides a detailed description of how the full well depth was evaluated. It also provides simple equations that allow photometric data well beyond saturation to be restored to excellent linear response. These equations contain a dependence on the full well depth local to the position of any object to be corrected.

The full well depth fits file images are available for download:
UVIS1 
UVIS2

LAST UPDATED: 06/17/2019

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