The FWHM of the Image Quality profile

If we suppose the seeing has a gaussian profile:

Where we have taken in count that

defining:

In this case we have:

For example, for a gaussian which has a maximum value of
*I*_{0}=141.55 and a FWHM of 840 Å.
The integral is:

(2.8) |

or

(2.9) |

(2.10) |

So the FWHM of the spatial profile can be calculated if one knows:

- The spatial profile distribution or
*I*_{tot},*I*_{max}