Now, that's what I was wondering! So, it's the gray line continued all the way around the globe, then. Which means that it doesn't have to be sunset to sunset stations or sunrise to sunrise stations. It can be sunrise for one and sunset for the other and still work! That is interesting, for sure! Thanks!My point was that true north/south propagation occurs with TE....or Trans-Equatorial propagation, and really does run pretty much due north and south. Gray line can happen between any two stations located on what is called the terminator......which is the band of twilight around the Earth. Gray line has happened from near the antipodes quite often and that is definitely not a simple north/south path. In the link below contacts are possible between eastern Brazil and Japan via gray line or even eastern Brazil and New Zealand......definately not N/S.
http://www.astrosurf.com/luxorion/qsl-propa5.htm