In a previous paper,¹ we described a method for significantly reducing the read noise of HAWAII-2RG (H2RG) and SIDECAR application specific integrated circuit (ASIC) based detector systems by making better use of reference signals. "Improved Reference Sampling & Subtraction" (IRS²; pronounced "IRS-square") is based on: (1) making better use of the H2RG's reference output, (2) sampling reference pixels more frequently in the time domain, and (3) optimal subtraction of both the reference output and reference pixels in the Fourier domain. Here we demonstrate that IRS² works as expected using an engineering grade James Webb Space Telescope (JWST) SIDECAR ASIC and H2RG detector array. We were able to reduce the read noise per frame from 25 e- rms using traditional JWST readout to 10 e- rms per frame using IRS². The only aspect of the system that we changed to make these impressive improvements was the SIDECAR ASIC readout software -we did not change the hardware.
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Rauscher et al. (2011) studied this question.