Characteristics of the NICMOS Detectors

We present an overview of the properties of the NICMOS flight detectors as measured on-orbit, including the flat-field response, the dark current, the linearity, and the read-noise. We show for the first time all the dependencies of the various components of a NICMOS dark exposure, and show how to generate “synthetic” dark current calibration files. An unexpected time-varying bias known as the “pedestal”, is described, along with some efforts to remedy it. We describe the effects on the detectors of exposure to very bright sources, and finally, we briefly describe the sensitivity of NICMOS to cosmic rays.