What is the relation between the wavelength and the radial velocity? I have a data: wavelength and intensity and I would like to plot intensity with respect to radial velocity - similarly as in the picture (source)
I have a file of alpha H with 2 columns - wavelength (in angstrom) and intensity (normalized for 1) and I would like to plot intensity with respect to radial velocity. I use in gnuplot:
c = 299792458 lambda_0 = 6562.817*10**(-10) plot 'file.asc' using (c*($1*10**(-10)-lambda_0)/lambda_0):2
Why I get the wrong range on the x-axis?