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| Paper: |
Representations of Spectral Coordinates in FITS |
| Volume: |
295, Astronomical Data Analysis Software and Systems XII |
| Page: |
403 |
| Authors: |
Greisen, E. G.; Valdes, F. G.; Calabretta, M. R.; Allen, S. L. |
| Abstract: |
In Paper I, Greisen & Calabretta (2003) describe a generalized method for specifying the coordinates of FITS data samples. Following that general method, Calabretta & Greisen (2003) in Paper II describe detailed conventions for defining celestial coordinates as they are projected onto a two-dimensional plane. The present paper extends the discussion to the spectral coordinates of wavelength, frequency, and velocity. World coordinate functions are defined for spectral axes sampled evenly in wavelength, frequency, or velocity, evenly in the logarithm of wavelength or frequency, as projected by ideal dispersing elements, and as specified by a lookup table. Papers I and II have been accepted into the FITS standard by the North American, Japanese and European FITS Committees; we expect the present work to be accepted as well. The full text of the proposed standards can be found at http://www.aoc.nrao.edu/~egreisen. |
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