학술논문
Detectors for the James Webb Space Telescope Near-Infrared Spectrograph I: Readout Mode, Noise Model, and Calibration Considerations
Document Type
Report
Author
Rauscher, Bernard J; Fox, Ori; Ferruit, Pierre; Hill, Robert J; Waczynski, Augustyn; Wen, Yiting; Xia-Serafino, Wei; Alexander, David; Brambora, Clifford K; Derro, Rebecca; Engler, Chuck; Garrison, Matthew B; Johnson, Thomas; Manthripragada, Sridhar S; Marsh, James M; Marshall, Cheryl; Martineau, Robert J; Shakoorzadeh, Kamdin B; Wilson, Donna; Roher, Wayne D; Cabelli, Craig; Garnett, James; Loose, Markus; Wong-Anglin, Selmer; Zandian, Majid
Source
Subject
Language
English
Abstract
We describe how the James Webb Space Telescope (JWST) Near-Infrared Spectrograph's (NIRSpec's) detectors will be read out, and present a model of how noise scales with the number of multiple non-destructive reads sampling-up-the-ramp. We believe that this noise model, which is validated using real and simulated test data, is applicable to most astronomical near-infrared instruments. We describe some non-ideal behaviors that have been observed in engineering grade NIRSpec detectors, and demonstrate that they are unlikely to affect NIRSpec sensitivity, operations, or calibration. These include a HAWAII-2RG reset anomaly and random telegraph noise (RTN). Using real test data, we show that the reset anomaly is: (1) very nearly noiseless and (2) can be easily calibrated out. Likewise, we show that RTN affects only a small and fixed population of pixels. It can therefore be tracked using standard pixel operability maps.