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How to Read IMAPS Files

This page provides information on reading the IMAPS data sets using FITS readers written in various languages. Basically, the raw data sets are standard primary array FITS files, while the coadded corrected files include the corrected image stored as a primary array, a binary table of wavelength information, and an image extension containing the noise filter image. (See Data Products for more details.) Both data sets should be readable by most FITS readers, and most FITS viewers (e.g., soaimage) should be able to display the spectral images.

Note that in the near future, IDL software will be made available to allow the extraction of flux versus wavelength using the coadded, corrected files.


One of the best supported, and most extensive, FITS readers is the FTOOLS and FITSIO software library written in C and FORTRAN by Bill Pence from HEASARC. These programs should be able to read all the various IMAPS data sets. The suite of programs can be built as either a stand-alone package or as an IRAF subpackage.

IDL FITS Readers

There are a number of FITS readers that are written using the Interactive Data Language (IDL) A number of the FITS readers are included in IDL libraries that are available for free via the WEB and run on several different platforms. (Note however that IDL must be purchased for the local computer). One such library is the IUEDAC software package, originally written for analyzing data from the International Ultraviolet Explorer (IUE) satellite project. The IUEDAC examples show how to use the program IFITSRD to read the raw, and coadded files. More information on IFITSRD can be found in the prolog of the program.

Another widely used IDL library is the IDL Astronomy User's Library. This library contains astronomy-related programs donated by several projects and includes several IDL FITS readers. Three of the FITS readers are described in the Astronomy Library examples. Additional documentation on all the listed IDL programs can be found in the procedure prologs.