EQF-you were asking Robert, but I am familar with Lowell's work and it is his work that got me interested in this. Lowell, I think, thought that 20 deg longitude either side of the sub-solar point at the time of a flare, and the 20 deg either side on the opposite side, was most likely to be triggered-esp. at high latitudes and on the magnetic equator-this is from memory, so someone can check the archives. I don't know whether it is the same for the subsolar point when the particles arrive later. I would think that the most important thing is where there is magnetic storminess on the ground. The Kp measures this for sites in North America, I think....The Kp is very quiet the last 24 hours including now-depsite the active sun. Chris