NOAA has changed how they put out the Ionospheric indices that are used in the NTIA/ITS HF Propagation Models.
Let's see how long this works.:)

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• The SunSpot Number (SSN) used by these HF prediction programs should be what is called R12 - the Smoothed SunSpot Number.
• Unfortunately R12 is no longer computed. But R13 is: R13 - the Smoothed SunSpot Number.
• For past values, use Historical Smoothed SSN (1749-2016) Indices table.
• For predicted values, use SMOOTH SSN from Predicted Indices table. Provided by Australia.
  • Make sure you scroll down and look at the graph.

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