  Interpixel capacitance (IPC) is a deterministic electronic coupling that
results in a portion of the collected signal incident on one pixel of a
hybridized detector array being measured in adjacent pixels. Data collected by
light sensitive HgCdTe arrays which exhibit this coupling typically goes
uncorrected or is corrected by treating the coupling as a fixed point spread
function. Evidence suggests that this IPC coupling is not uniform across
different signal and background levels. This variation invalidates assumptions
that are key in decoupling techniques such as Wiener Filtering or application
of the Lucy- Richardson algorithm. Additionally, the variable IPC results in
the point spread function (PSF) depending upon a star's signal level relative
to the background level, amond other parameters. With an IPC ranging from 0.68%
to 1.45% over the full well depth of a sensor, as is a reasonable range for the
H2RG arrays, the FWHM of the JWSTs NIRCam 405N band is degraded from 2.080 pix
(0".132) as expected from the diffraction patter to 2.186 pix (0".142) when the
star is just breaching the sensitivity limit of the system. For example, when
attempting to use a fixed PSF fitting (e.g. assuming the PSF observed from a
bright star in the field) to untangle two sources with a flux ratio of 4:1 and
a center to center distance of 3 pixels, flux estimation can be off by upwards
of 1.5% with a separation error of 50 millipixels. To deal with this issue an
iterative non-stationary method for deconvolution is here proposed,
implemented, and evaluated that can account for the signal dependent nature of
IPC.
