Stellar Aberration: the 'stationary' and the 'moving' perpendicular.
Frank Pio Russo - November 19, 2014.
Ever since the early days of Bradley - who used a plumb line - the perpendicular has been very important to stellar aberration. Way back in 1992 I saw that the aberration angle was something that depended on the motion of the observer and that I could therefore extricate the absolute speed of light and of the earth out of it.
Also, decades ago I differentiated between a 'stationary' perpendicular and a 'moving' perpendicular as viewed from a star that's emitting the beams of light. The 'stationary' perpendicular would come out at 90 degrees and would be bent backwards by the motion (whilst moving), whereas the 'moving' perpendicular would have to be aimed forward so as to give you an 'apparent' perpendicular whilst moving.
Of course, in the 'stationary' perpendicular the length travelled by light per unit of time would not be inflated and would equal the 'aberration' speed of 304,475,873.2 m/sec (whereas the bent version would appear to be going at 309,232,453.6 m/sec)... as for the 'moving' perpendicular beams, the light paths would be inflated by the extra motion along the hypotenuse and would therefore have a slowed 'vertical' speed... (which in our vicinity is about 299,792,458 m/sec).
In conclusion, I will add a link that will show how clearly I saw the issue from decades ago:
Frank Pio Russo.