lunedì 28 Settembre 2020
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The K7RA Solar Update

No sunspots again this week. This run of zero sunspots has persisted for over three weeks.

In last week’s bulletin, we erroneously said that average daily sunspot number for the week was 70.4, but as KB8W pointed out this was the value of average daily solar flux. Average daily solar flux for this week, November 28 through December 4, was 70.2.

Geomagnetic indicators were very quiet, with average planetary A index declining from 8.3 to 3.4, while average mid-latitude A index slipped from 5.7 to 2.

Predicted solar flux for the next 45 days is 70, in fact that is the value forecast for every one of those days, all the way through January 19.

Predicted planetary A index is 5 on December 6-7, then 8 on December 8-9, 5 on December 10-17, then 12, 10, 8 and 8 on December 18-21, 5 on December 22-29, 8 on December 30-31, 5 on January 1-3, 8 on January 4, 5 on January 5-8, 6 on January 9, 5 on January 10-13, then 12, 10, 8 and 8 again on January 14-17, and 5 on January 18-19. pointed out the Geminid meteor shower is coming up soon, peaking December 13-14, just in time for the ARRL Ten Meter Contest next week on December 14-15. Ionized meteor trails may enhance 10-meter propagation. This article from 2012 describes the source of the Geminids: This year the full moon appears on December 12, which may interfere with viewing the meteor shower.

F.K. Janda, OK1HH sent his geomagnetic activity forecast for the period December 6-31, 2019

Geomagnetic field will be:
quiet on: December 12, 15-17, 23, 28-31
quiet to unsettled on: December 9-11, 13, 24-27
quiet to active on: December 6-8, 14, 18, 22
unsettled to active on: December 21
active to disturbed: (19-20)

Solar wind will intensify on: December (13-14, 16,) 18-21
Parenthesis means lower probability of activity enhancement.
Everything suggests that we are very close to the minimum of the 11-year cycle now.

Updates on the Parker Solar Probe (thanks to Max White): and

Thanks to David Moore for this on solar magnetic waves:

Jon Jones, N0JK reported on 6 meter sporadic-e on December 4: “The winter sporadic-E season began with a strong, long lasting Es opening across North America and the Caribbean December 4. Es first appeared early around 1400z from W5 to W8 and lasted all day to 0040z December 5.

“I was on from home (Lawrence, KS EM28) around 1830z and made a dozen 6-meter FT8 contacts in Florida and Georgia.

“Later while driving from Lawrence to Salina, I stopped on highway 177 south of Manhattan, Kansas (EM18) and set up a “fixed mobile” station. I was operating with just 10 watts and a 1/4 wavelength magnet mount antenna. I made seven FT8 contacts with Florida, Georgia, and Virginia. I was called by WA1EAZ in FN42 and decoded WU1ITU FN65 several times. N0LL (EM09) decoded HH2AA, but no contact. Other DX included TI5/N5BEK, XE1MEX, XE2AT, XE2JS, HI8DL, HI8PLE, KP4EIT, HI8RD, NP3XF, NP4BM, and LU5FF Es – TEP by KW4BY.”

The Royal Observatory of Belgium ( has an interesting page showing sunspot number predictions for the next 12 months:

Thanks to Max White for this, on observing the ionosphere from Antarctica:

Found this on Galileo’s sunspot drawings, presented as animation:

The ARRL 160 meter contest begins today at 2200 UTC. The predicted quiet geomagnetic conditions are a good sign. See for details.

If you would like to make a comment or have a tip for our readers, email the author at

For more information concerning radio propagation, see and the ARRL Technical Information Service at For an explanation of numbers used in this bulletin, see

An archive of past propagation bulletins is at More good information and tutorials on propagation are at

Monthly propagation charts between four USA regions and twelve overseas locations are at

Instructions for starting or ending email distribution of ARRL bulletins are at

Sunspot numbers for November 28 through December 4, 2019 were 0, 0, 0, 0, 0, 0, and 0, with a mean of 0. 10.7 cm flux was 70.2, 69.8, 70.4, 71.2, 70.4, 69.9, and 69.6, with a mean of 70.2. Estimated planetary A indices were 4, 5, 4, 4, 2, 2, and 3, with a mean of 3.4. Middle latitude A index was 2, 3, 2, 2, 2, 1, and 2, with a mean of 2. (

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