wl2pix: Compute the pixel for a specific wavelength in a spectrum
Package: rvsao
Usage
wl2pix spectrum wavelength
Parameters
- spectrum
- Spectrum image file with dispersion function
- specext = 0
- Spectrum extension number in multiextension FITS image
- specnum 0
- Spectrum number in multispec image (order in echelle image)
- specband 0
- Spectrum band in multispec image
- wavelength INDEF
- Wavelength in Angstroms for pixel
- pixel INDEF
- Pixel at specified wavelength (returned)
- pixform "%8.3f"
- IRAF format for pixel output
- waveform "%8.3f"
- IRAF format for wavelength output
- nsum = 1
- Number of pixels to sum across dispersion
- verbose no
- If yes, print the pixel value
- debug = no
- If yes, print the file name, transformation, and wavelength per pixel
Description
Compute the pixel value for a given wavelength in a spectrum, saving the value as the pix2wl.pixel parameter. If verbose=yes, print the pixel value using the pix2wl.pixform format. If debug=yes, print spectrum image name, followed by the wavelength value using the pix2wl.waveform format, the pixel falue using the pix2wl.pixform format, and the delta wavelength per pixel across this pixel.
Examples
1) Compute the pixel at a given wavelength for use in a CL script:
rvsao> wl2pix 22572.fits 7000
rvsao> =wl2pix.pixel
3982.3984617936
rvsao>
2) Print the pixel at a given wavelength:
rvsao> wl2pix 22572.fits 7000 v+
3982
rvsao>
3) Print the pixel at a given wavelength more verbosely:
rvsao> wl2pix 22572.fits 7000 d+
22572.fits: 7000.000 -> 3982 (0.5744/pix)
rvsao>
4) Check the inverse of the dispersion function:
rvsao> wl2pix 22572.fits 7000
rvsao> pix2wl 22572.fits wl2pix.pixel v+
7000.000
rvsao>