FBsLights excellent diagram of sliced 519a with different hights (btw. the jump of the BBL at 5000K is because up to 5000K it is a pure black body line and above 5000K it incorporates the filter effects of earth atmosphere → it jumps up a bit)
https://i.imgur.com/K0pDkCv.jpg[/img]
Source: FBsLights