spec_s2n

spec_s2n.cl

Name

spec_s2n -- estimate the S/N for multispec-format spectra

Usage

spec_s2n input

Parameters

input
Name(s) of multispec-format image(s) to process.

Description

This task will compute and print an empirical estimate of the signal-to-noise ratio in each aperture of a multispec-format image. Each multispec-format spectrum contains a signal band (assumed to be band 1) and a noise band (band 4) which is an estimate based on read noise and poisson statistics. The task simply computes the estimated S/N in each pixel by taking the ratio of these two bands, then computes the median of all the S/N values in the spectrum to derive a median S/N for the spectrum. The operation is repeated for each aperture in the image.

If multiple images or apertures are specified, the quadrature sum of the S/N values for all spectra is printed.

Examples

  1. Compute the median S/N in spectrum 24des0073cy.ms.fits:
    wm> spec_s2n 24des0073cy.ms.fits
      Image: 24des0073cy.ms.fits  S/N: 3.6 per pixel (median)
  2. Compute the median S/N of all spectra in a dataset:
    wm> spec_s2n *.ms.fits
      Image: 24des0073cy.ms.fits  S/N: 3.6 per pixel (median)
      Image: 24des0074cy.ms.fits  S/N: 3.1 per pixel (median)
      Image: 24des0075cy.ms.fits  S/N: 3.6 per pixel (median)
      Image: 24des0076cy.ms.fits  S/N: 4.4 per pixel (median)
      Image: 24des0077cy.ms.fits  S/N: 7.7 per pixel (median)
      Image: 24des0078cy.ms.fits  S/N: 6.9 per pixel (median)
      Image: 24des0079cy.ms.fits  S/N: 8.0 per pixel (median)
      Image: 24des0080cy.ms.fits  S/N: 9.1 per pixel (median)
      Image: 24des0081cy.ms.fits  S/N: 9.8 per pixel (median)
      Image: 24des0082cy.ms.fits  S/N: 6.8 per pixel (median)
      Image: 24des0083cy.ms.fits  S/N: 10.0 per pixel (median)
      Image: 24des0084cy.ms.fits  S/N: 10.6 per pixel (median)
      Image: 24des0085cy.ms.fits  S/N: 10.2 per pixel (median)
      Image: 24des0086cy.ms.fits  S/N: 9.3 per pixel (median)
      Image: 24des0087cy.ms.fits  S/N: 9.3 per pixel (median)
      Image: 24des0088cy.ms.fits  S/N: 9.9 per pixel (median)
      Image: 24des0089cy.ms.fits  S/N: 7.7 per pixel (median)
      Image: 24des0090cy.ms.fits  S/N: 8.0 per pixel (median)
      Image: 24des0091cy.ms.fits  S/N: 7.7 per pixel (median)
        Quadrature sum: 34.9 per pixel

See Also

imarith imstat
The cl script spec_s2n.cl
The package wmkonspec
Last modified: 07/13/2017 02:41
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