WikiLeaks has released nearly “half a million US national text pager intercepts. The intercepts cover a 24 hour period surrounding the September 11, 2001 attacks in New York and Washington.” More information, including the intercepts themselves, are available from the WikiLeaks web site.
I’ve gone through the intercepts and created this chart. For each ten minute block of time from 3am on Tuesday September 11th, 2001 though 2:59am on Wednesday, September 12th, 2001, I’ve plotted the number of intercepts, as well as labeled a few of the more important events of the 9/11 attacks.
This is the entire dataset as downloaded from WikiLeaks:
(Click the chart for a larger version.)