Detection of rocket launches via ionospheric disturbances. This is using #GPS data published by Japan, detecting the North Korea missile test.
https://twitter.com/tylerni7/status/1593453980382007296
It works by comparing GPS data paths on two different bands to estimate the total electron content (TEC) in the #ionosphere. Very cool.
I found out about this from the #ArmsControlWonk podcast. Recommended. https://www.armscontrolwonk.com/
"How Sting Likes to Test"
"Jeeze that was a big missile. North Korea has tested another large ICBM, and this one was (another) doozy. Jeffrey and Aaron talk through modelling this missile, the potential theft of missile tech from Ukraine, Kim Jong Un’s Bring Your Daughter to Work Day..."
https://www.armscontrolwonk.com/archive/1216687/how-sting-likes-to-test/