December 2021 Eclipse Festival of Frequency Measurement


Calling all stations: Join us for
The December 2021 Antarctic Eclipse Festival

01 December 2021 0000 to 10 December 2021 2359 UTC





Changes in ionospheric electron density caused by space weather and diurnal solar changes are known to cause Doppler shifts on HF ray paths. For example, see Figure 7 in Boitman et al., 1999. HamSCI's first attempt at a measurement of these Doppler shifts was during the August 2017 total solar eclipse.  We plan a careful measurement during the 2024 eclipse. As part of the WWV centennial, 50 stations collected Doppler shift data for the original Festival of Frequency Measurement, demonstrating the value of volunteer participation in collecting this data. This year, we request that all amateur radio stations, shortwave listeners, and others capable of making high-quality HF frequency measurements help us collect frequency data for the December 4 solar eclipse across Antarctica.



Contact information:

Kristina Collins:


Research Questions

  • How do the propagation paths of shortwave time standard stations vary over a calendar day?
  • What properties of the ionosphere are we able to measure by observing the variation in these HF propagation paths?
  • What effect will the annular eclipse have on these propagation paths?
  • How do various measurement techniques for understanding the path variation compare?
  • Is there volunteer interest in collecting data in the regions near totality for this eclipse?



  • Promote international goodwill by working with citizen scientists around the globe
  • Measure Doppler shifts caused by space weather's effects on the ionosphere.



  • Data recording starts: 01 December 2021, 0000 UTC
  • Data recording ends: 10 December 2021,  2359 UTC




Please begin measurements before the day's start time and end them after the finish time, if possible.


How to Participate

1) Sign up on the Eclipse Festival mailing list:

2) Collect data according to the instructions on this page:

3) Submit data here: