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Astronomy files

IRAF multispec polynomial sampler

Sample an extracted dtype-2 multispec calibration at explicit logical pixels.

Your inputs

Start with an example

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Your result

Example result

How it works

Convert p=(logical−LTV)/LTM, evaluate Chebyshev or Legendre functions, normalize the weighted sum by total function weight, then divide by 1+z. The maintained IRAF evaluator determines the weight normalization.

The Chebyshev example evaluates 100+10n+2(2n²−1) at n=−1,0,1, yielding 92,98,112 nm.

Limits

Extracted numeric dtype-2 attributes only: no FITS/WAT card joining, splines or other dispersion modes. Up to 64 functions, order 128 and 4096 samples with bounded basis work. Zero total weight rejects. Pixels outside nw or a function’s calibration domain stay unknown; no extrapolation or scientific fit-quality claim.