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
- 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)
- 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