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air_to_vacuum

Convert the wavelength axis from air to vacuum wavelengths.
Category Corrections
Backend numpy - implemented here on top of numpy primitives
Version 1.0.1
Reads ctx.spectrum (a Spectrum1D)
Writes spectrum

λ_vac = λ_air · n(λ_air) with the VALD3 closed-form inverse of Morton 2000 (coefficients 8.336624212083e-5, 2.408926869968e-2/(130.1065924522 - s²), 1.599740894897e-4/(38.92568793293 - s²), s = 1e4/λ[Å]). Acceptance: Hα 6562.79 → 6564.603 Å. Valid above ~2000 Å.

Parameters

This algorithm takes no parameters.

Use it

from spectro_kernel import run_algorithm

output = run_algorithm("air_to_vacuum", ctx, {})

spectro run air_to_vacuum --input spectrum.fits

{
  "tool": "air_to_vacuum",
  "arguments": {
    "session_id": "<session_id>",
    "params": {}
  }
}

Every algorithm is an MCP tool of the same name; describe_algorithm returns this page's metadata as JSON.

References

  • Piskunov N., VALD3 'Air to vacuum conversion' (Uppsala VALD wiki, https://www.astro.uu.se/valdwiki/Air-to-vacuum%20conversion) — closed-form inverse fit n(λ_air) of the Morton 2000 relation.
  • Morton 2000, ApJS 130, 403 — air/vacuum dispersion relation n(λ_vac).