-- New Conversion Tools for 1D Image Spectra
One dimensional spectra are sometimes imported and exported in the form of
a text file with columns of wavelength and flux. While there are tools
scattered about that do some of the desired conversions---sinterp,
listpixels, r/wtextimage, mkmultispec (in
the STSDAS package)---two specific
tasks that provide
these conversions in a complete (both header and pixels) and flexible
(linear and non-linear dispersion functions) way have been added to IRAF
V2.10.3BETA / V2.11. These new tasks are in the onedspec package and
are called
rspectext, for
reading a text file into a 1D IRAF spectral image, and
wspectext,
for writing
a text file from an IRAF spectral image. Naturally,
the output of wspectext
can be read by rspectext without loss of header or dispersion information.
Often, rspectext is used for import of a purely wavelength/flux file
without header information. The task will take care of defining the
necessary header keywords.
One very important feature of rspectext is that it provides three
alternative ways to store dispersion information in the output IRAF image.
One is to fit and resample the
input to a linear dispersion function. Alternatively, the spectrum can be
represented using a non-linear function fit to the input wavelengths, or the
wavelengths can be entirely stored as a lookup table (which is not
recommended for very long spectra).
Frank Valdes
This document was translated by ms2html v1.8 on 21Jan95.