Nonlinearity corrections and statistical uncertainties associated with near-infrared arrays

We derive general equations for nonlinearity 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 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 nondestructive 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 it may be due to heating of the array as a result of the multiple readouts. Such behavior may be generic to arrays that employ correlated or multiple correlated double sampling readouts.