[math]\vartriangleleft [/math] [math]\triangle [/math] [math]\vartriangleright [/math]
If the conic is an circle, e=0. This implies
Using the relation
The sector angle will never be perpendicular to the plane of the light cone, so this is not a physical possibility.
[math]\vartriangleleft [/math] [math]\triangle [/math] [math]\vartriangleright [/math]