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H. Bushouse, A. Sivaramakrishnan, M. Dickinson, A. Nota (STScI)
Certain unpredictable behaviors of the NICMOS instrument on-board HST often lead to image anomalies that are not able to be removed by standard pipeline processing of the data. Some of the more common anomalies are bias offsets, bias jumps, residual shading signal, pairs of high and low columns or rows (known as ``bars''), and cosmic-ray persistence. Some of these anomalies can be corrected through the application of temperature-dependent calibration data. Others require dedicated analysis and reduction software tools. The STScI NICMOS and Science Software Groups have begun development of a package of IRAF/STSDAS tools to be used for performing these specialized tasks, outside of the current pipeline processing scheme. This package includes a combination of display, analysis, and correction tools. The display and analysis tools allow a NICMOS observer to identify the existence and evaluate the severity of the various image anomalies. The correction tools are tailored to then remove or correct for the specific problem conditions. We will describe the symptoms of each type of anomaly and demonstrate the use of the analysis and correction tools that are used to address them.
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