I am attempting to understand derivation of v sin.i and would appreciation some clarification of my understanding of the process.
If I understand correctly (using an absorption line profile with no emission component), would I first establish the fwhm position on the profile and determine the distance in angstroms from the profile center to the profile line at fwhm? This would be the wavelength shift that I would then enter into the standard RV formula along with the actual rest wavelength of the line and c. Does this sound correct or am I missing something? I realize I am not correcting for microturbulence or macroturbulence at this stage(first things first

Thanks,
Keith Graham