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Paper: NICMOS Bias Dependent Calibration
Volume: 434, Astronomical Data Analysis Software and Systems XIX
Page: 374
Authors: Pirzkal, N.; Dahlen, T.; Bergeron, E.; Wiklind, T.
Abstract: We present our latest calibration work of the NICMOS instrument on the Hubble Space Telescope. This new calibration method uses a novel method to determine the Q.E. of the detector, expressed as an effective temperature called biastemp, directly from the science exposure. This has allowed, as we show here, to better monitor the behavior of the instrument’s three detectors, providing calibration files that account for changes in photometry, flat-fields, and different components of the dark signal, including the shading and the amplifier glow. It has also allowed us improve the calibration of this instrument by providing bias level specific calibration files such as flat-fields, darks, and shading. We express this as an idealized temperature (biastemp) of the instrument which is determined from the bias level of the data, and which is determined using the first read of these non-destructive read, multi-accum datasets. It has allowed us to determine this biastemp value of each of the three NICMOS detectors to within 0.05K and offers a significant improvement over the available mounting cup temperature sensor that has been used in the past, as it is as precise but is a direct measurement of the state of the detector, whether truly due to a change in temperature or internal voltage supply.
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