Don, some clarification (you may know this, but it is not clear in your note: Xrays are electromagnetic, so take 8 minutes to get to earth. Protons, I guess, are particles and take longer. I accidently clicked on the bar graph at the NOAA link below and it gave a blow up of Kp index and an explanation-it is measured on the ground. This is most likely to be important for earthquakes. It was Kp8 earlier today, which is probably major storm. It has quieted down, but last nights space weather forecast called for severe storm. Not a good time to fly from London to Tokyo over the artic.....Chris