Seeing FWHM arcsec to Gaussian Sigma Converter
Exact Gaussian FWHM=2 sqrt(2 ln 2)σconversion, not Moffat PSF or actual seeing Gaussian fit. Caller independently establishes frames, units, epoch, covariance and instrument context; not an identity, association or astrometric quality certification.
Description
A Gaussian profile connects its full width at half maximum to its standard deviation.
A Gaussian profile connects its full width at half maximum to its standard deviation.1
Non-Gaussian seeing profiles need their own width convention. Use Seeing FWHM arcsec to Gaussian Sigma Converter to evaluate the supplied inputs under the model explained below.
When to use Seeing FWHM arcsec to Gaussian Sigma Converter
Use Seeing FWHM arcsec to Gaussian Sigma Converter to evaluate the supplied inputs under the model explained below. Establish the units, measurement scope and model assumptions before entering values.
How to use Seeing FWHM arcsec to Gaussian Sigma Converter and understand its results
- Establish the units, measurement scope and model assumptions before entering values.
- Enter Gaussian fwhm arcsec using the field table and validation rules below, then run the tool.
- Read Gaussian sigma arcsec; interpret the units, signs, ordering and unknown-value placeholders described below.
- Correct reported input errors and rerun. Apply successful results according to their specific meanings and check the assumptions before using them in a decision.
| Input field | Meaning | Value type | Requirement |
|---|---|---|---|
| gaussianFwhmArcsec | Gaussian fwhm arcsec | number | Required; constraints below |
Enter nonnegative Gaussian FWHM in arcsec. Divide by 2sqrt(2ln2) to return sigma in arcsec. Zero width returns zero; no PSF fit or conversion for a different profile shape occurs.
sigmaArcsec=FWHMArcsec/(2sqrt(2ln2)) Use the field order, units and branch conditions described above.
| Output field | Meaning | Value type |
|---|---|---|
| gaussianSigmaArcsec | Gaussian sigma arcsec | number |
{
"input": {
"gaussianFwhmArcsec": 2.3548200450309493
},
"output": {
"gaussianSigmaArcsec": 1
}
}Limitations and assumptions
Non-Gaussian seeing profiles need their own width convention. Apply the exact scope and assumptions explained above.
All listed fields require explicit values. Unexpected fields, incorrect types, nonfinite numbers and sparse arrays fail validation. Domain-specific bounds, alignments and supported tokens are explained above; extremely large inputs or outputs can also be rejected. Input errors differ from successful false results, empty match lists and unknown-evidence placeholders.
Alternative or Complementary methods
Use Dawes Resolving Limit Arcsec for a related task: Dawes' relation is an empirical double-star resolution heuristic tied to aperture.
Use Speckle Interferometry Diffraction Limit lambda/D Resolution Check for a related task: The Rayleigh relation describes ideal circular-aperture angular resolution.
References
Similar or alternative tools
- Dawes Resolving Limit Arcsec
Dawes' relation is an empirical double-star resolution heuristic tied to aperture.
- Speckle Interferometry Diffraction Limit lambda/D Resolution Check
The Rayleigh relation describes ideal circular-aperture angular resolution.