The MAST IUE archive contains files processed with
two different image processing systems:
The official IUE final archive was created using NEWSIPS,
and all NEWSIPS files are archived using
FITS format. These are the
recommended files for MAST users.
The original IUE image processing system was known as IUESIPS.
IUESIPS files are available in either the project-defined
or the IUE Data Analysis Center derived
(RDAF and GO format files can be easily converted to one another
using available IUEDAC IDL routines.)
In order to reduce file transfer times, files requested via the web
are downloaded using one of three compression options:
.tar - uncompressed files bundled in a tar file. (Note,
prior to 10/21/99, the individual files were also gzipped by default.)
.tar.gz - files are bundled into a tar file which is then
compressed using gzip.
.zip - files are bundled (and compressed) into a zip file,
File requested via
are downloaded as individual gzipped files.
For more information on downloading and reading IUE files on
different platforms see the
data retrieval help page.
More information on the
individual IUESIPS and NEWSIPS files is given below.
Clicking on the data type names listed below
will display the detailed file descriptions
as described in the IUE image processing information manuals.
NEWSIPS FITS Files
MXHI - The merged extracted spectral files contain the absolutely-calibrated
fluxes, wavelengths, data quality flags, and sigmas (or noise estimate for
MXHI files) in a FITS binary table extension.
The high dispersion files are named MXHI and the low dispersion files are MXLO.
Note that although low dispersion double aperture exposures are listed as two
separate entries on the search results page, both spectra are
contained in one MXLO file.
SILOSIHI - The resampled image files (SILO & SIHI) are the files
from which the fluxes were extracted.
The SI files contain the photometrically-corrected and rotated image
as a primary array, wavelength information in a binary table extension,
and an image extension containing an array of
data qualiy flags. These files are useful for identifying camera artifacts
such as cosmic ray hits, etc.
The RILO, RIHI raw image files (a 768x768 byte primary array image) and the
LILO, LIHI linearized image files
(a 768x768 integer primary array file with associated data
quality flags as a 768x768 integer array image extension) are also available.
IUESIPS GO-Format Files
The merged extracted spectral files containing scaled vectors of
wavelengths, and gross, background, net and
absolutely-calibrated net fluxes for each extracted spectral order.
Available for low dispersion images only, these are the extended
line-by-line (spatially-resolved) files from which the extracted fluxes
are obtained. Useful for identifying reseaux and camera artifacts.
Pixel values are stored in IUE FN units.
RI - The 768x768 raw image files containing
a VICAR label (as do all IUESIPS files), and 768 records of 768 bytes each.