[fitswcs] Grisms

[Steve Allen]

Hi William,

On Fri 2005-04-22T15:28:40 -0400, William Thompson hath writ:
> Unless I've made a mistake anywhere, this should be discussed in the text.
> If one tries to establish the 7 parameters by means of a least squares fit,
> one ends up with a degenerate problem.  I anticipate that fitting would be
> a common procedure--that's certainly what we do today, except that we
> usually fit polynomials.

This is addressed in the second paragraph of section 5 where we admit
that the grism model does not address the full ray-tracing complexity
of real spectrographs and that the table lookup and polynomial methods
of paper IV may be preferable.

--
Steve Allen          UCO/Lick Observatory       Santa Cruz, CA 95064
sla at ucolick.org      Voice: +1 831 459 3046     http://www.ucolick.org/~sla
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