ISAP - Introduction

The ISO Spectral Analysis Package (ISAP) is a software package, based on Interactive Data Language (IDL - a trademark of Research Systems Inc.), for the reduction and scientific analysis of ISO SWS and LWS, CAM-CVF, and PHT-S  Auto Analysis Results (AARs).  It is developed by a collaboration involving people from the SWS and LWS Instrument Dedicated and Support Teams (MPE, RAL, SRON, VILSPA), IAS( Orsay) and IPAC (Caltech, Pasadena).

 The AAR for SWS and LWS spectra, which is the final result of the standard ISO pipeline processing, is a complex FITS table with data for 14 parameters for each detector element readout at each grating position (wavelength). More than one data point (and thus more than one row in the data table) may be present at a given  wavelength, and likewise data at any given wavelength may originate from different detectors, grating orders, and/or apertures, representing numerous up and down directional scans over the spectral region of interest. The spectral resolution and sampling (spacing between data points) varies with wavelength. Data for the grating and Fabry Perot modes of the SWS07 AOT are contained within the same FITS table. Residual instrumental signatures not removed by the pipeline processing (e.g., fringing) may be present in the AAR. Differences may also persist in detector calibration and responsivity which manifest as discontinuities in the continuum flux from one detector to another. Because of these and other complexities, the AAR needs further processing before it can be used for a scientific analysis.

 ISAP aims to offer a complete software package for the required processing and scientific analysis of LWS and SWS AARs. Its primary function is to simplify the process of visualizing, subsetting, shifting, rebinning, masking, combining scans with weighted means or medians, filtering, and smoothing the AARs. The result of a typical ISAP session is expected to be a "simple spectrum" (single-valued spectrum which may resampled to a uniform wavelength separation if desired) that can be further analyzed and measured either with other ISAP functions, native IDL functions, or exported to other analysis package (e.g., IRAF, MIDAS) if desired. For further analysis, line-fitting, and continuum measurements,  ISAP provides many tools, such as routines for unit conversions, conversions from wavelength space to frequency space, line and continuum fitting, flux measurement, synthetic photometry and models such as a zodiacal light model to predict and subtract the dominant foreground at some wavelengths.

Note: ISAP will now also read in Post Mission Archive "Browse Products," although these are meant as indicators of available archive data and not in themselves appropriate for scientific analysis.

ISAP Home Page 

Last update: 22 March - 2001