Non-Linearity Corrections and Statistical Uncertainties Associated with Near-Infrared Arrays

Abstract

We derive general equations for non-linearity corrections and statistical uncertainty (variance) estimates for data acquired with near-infrared detectors employing correlated double sampling, multiple correlated double sampling (Fowler sampling) and uniformly-spaced continuous readout techniques. We compare our equation for the variance on each pixel associated with Fowler sampling with measurements obtained from data taken with the array installed in the near-infrared cross-dispersed spectrograph (SpeX) at the NASA Infrared Telescope Facility and find that it provides an accurate representation of the empirical results. This comparison also reveals that the read noise associated with a single readout of the SpeX array increases with the number of non-destructive reads, n_r, as n_r^0.16. This implies that the {effective} read noise of a stored image decreases as n_r^-0.34, shallower than the expected rate of n_r^-0.5. The cause of this read noise behavior is uncertain, but may be due to heating of the array as a result of the multiple read outs. Such behavior may be generic to arrays that employ correlated or multiple correlated double sampling readouts.