.help rspectext Oct93 onedspec
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NAME
rspectext -- convert 1D ascii text spectra to IRAF image spectra
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USAGE
rspectext input output
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PARAMETERS
.ls input
Input list of ascii text spectra.  These may have a optional FITS header
at the beginning and then two columns of wavelength and flux.
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.ls output
Output list of IRAF spectra image names.  The list must match the
input list.
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The following parameters are only used if there is no FITS header
with the data.
.ls title = ""
Title to be assigned to the spectra.
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.ls flux = no
Are the flux values flux calibrated?  If so then header keywords are
inserted to identify this for the IRAF spectral software.
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.ls dtype = "linear" (none|linear|log|nonlinear|interp)
Type of dispersion to assign to the spectra.  The options are:
.ls none
No dispersion function and nothing is added to the image header.
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.ls linear
Store the linear dispersion parameters \fBcrval1\fR and \fBcdelt1\fR
in the image header.  The wavelength values are ignored.  This may
be used if the wavelength values are known to be linear but one wants
to avoid possible roundoff and resampling errors introduced by the
"interp" option.
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.ls log
Store the log-linear dispersion parameters \fBcrval1\fR and \fBcdelt1\fR in
the image header.  The wavelength values are ignored.  This may be used if
the wavelength values are known to be linear in the log of the wavelength
but one wants to avoid possible roundoff and resampling errors introduced
by the "interp" option.
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.ls nonlinear
Store the wavelength values in the image header as a lookup table.
The flux values are not resampled.  The wavelength values need not
be evenly sampled.
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.ls interp
Use the wavelength values to resample to a linear dispersion between
the first and last wavelength values.  The dispersion per pixel is
determined by the number of pixels and the endpoint wavelengths.
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.ls crval1 = 1., cdelt1 = 1.
The wavelength coordinate of the first pixel and the wavelength interval
per pixel to be used with the linear and log dispersion types.
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DESCRIPTION
Ascii text files consisting of an optional FITS header (usually produced
by \fBwspectext\fR) and a two column list of wavelengths and fluxes
are converted to IRAF image spectra.  If a header is included then
the header information is assumed to describe the spectra including
any dispersion function.  If no header is given then the minimal
information for describing spectra in IRAF is added.  The dispersion
function can be set either a linear or log-linear based on two
keywords (ignoring the wavelength values) or from the wavelength
values.  The latter may be stored in the header as a lookup table
allowing for nonlinear dispersions or resample to a linear dispersion.
This task is a script based on \fBrtextimage\fR for the creating
the image and entering the flux values, \fBhedit\fR to set some
of the header keywords, and \fBdispcor\fR to handle the nonlinear
or resampled dispersion functions.
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EXAMPLES
1.  Create spectrum from a text file originally produced by \fBwspectext\fR.

.nf
    cl> type text001
    BITPIX  =                    8  /  8-bit ASCII characters
    NAXIS   =                    1  /  Number of Image Dimensions
    NAXIS1  =                  100  /  Length of axis
    ORIGIN  = 'NOAO-IRAF: WTEXTIMAGE'  /
    IRAF-MAX=                   0.  /  Max image pixel (out of date)
    IRAF-MIN=                   0.  /  Min image pixel (out of date)
    IRAF-B/P=                   32  /  Image bits per pixel
    IRAFTYPE= 'REAL FLOATING     '  /  Image datatype
    OBJECT  = 'TITLE             '  /
    FILENAME= 'TEST              '  /  IRAF filename
    FORMAT  = '5G14.7            '  /  Text line format
    APNUM1  = '1 1     '
    DC-FLAG =                    0
    WCSDIM  =                    1
    CTYPE1  = 'LINEAR  '
    CRVAL1  =                4000.
    CRPIX1  =                   1.
    CDELT1  =     10.1010101010101
    CD1_1   =     10.1010101010101
    LTM1_1  =                   1.
    WAT0_001= 'system=equispec                                 '
    WAT1_001= 'wtype=linear label=Wavelength units=Angstroms   '
    END
										    
    4000.00  1000.
    4010.10  1005.54
    4020.20  1011.05
    ...
    cl> rspectext text001 spec001
.fi

2.  Create a spectrum with a nonlinear dispersion using the wavelength
values as a lookup table.

.nf
    cl> type text002
    4000.00  1000.
    4010.10  1005.54
    4020.20  1011.05
    ...
    cl> rspectext text002 spec002 title="HH12" dtype=nonlinear
.fi
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REVISIONS
.ls RSPECTEXT V2.11
The task now automatically senses the presence of a header.
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.ls RSPECTEXT V2.10.3
This is a new task with this version.
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SEE ALSO
wspectext, rtextimage, dispcor, mkms, imspec, sinterp
.endhelp