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The K7RA Solar Update

Tad Cook, K7RA, Seattle, reports: Sunspot numbers started strong at 124 this reporting week, September 9-15, but ended at zero. Average daily sunspot numbers went from 64.6 to 58.3. Average daily solar flux declined from 92.9 to 87.4.

Geomagnetic indicators remained moderate, with last week’s average daily planetary A index unchanged at 7, and average daily middle latitude A index changed from 7.7 to 6.9.

Predicted solar flux is much lower than last week’s bulletin reported. Solar flux is predicted at 75 on September 17 – 23; 76 on September 24 – 26; 78, 80, and 82 on September 27 – 29; 86 on September 30 – October 10; 82 on October 11 – 12; 80 on October 13; 78 on October 14 – 17; and 76 on October 18 – 23. Solar flux is expected to rise to 89 by the end of October.

Predicted planetary A index is 15 on September 17 – 18; 8 on September 19 – 20; 5 and 8 on September 21 – 22; 5 on September 23 – October 3; 8 and 12 on October 4 – 5; 5 on October 6 – 17; 8 on October 18, and 5 on October 19 through the end of the month.

Here’s the geomagnetic activity forecast for September 17 – October 12 from F.K. Janda, OK1HH.

The geomagnetic field will be:

quiet on September 19, 29 – 30, October 9 – 10
quiet to unsettled on September 20, 28, October 1, 4, 7, 12
quiet to active on September 17 – 18, 22 – 23, 25 – 27, October 3, 8, 11
unsettled to active on September 21, 24, October (2,) 5 – 6
Active to disturbed Nothing predicted
Solar wind will intensify on October 11.

Remarks:

– Parentheses mean lower probability of activity enhancement.

– The confusing situation mentioned 2 weeks ago together with the variable configuration of active areas and coronal holes was a sign of the subsequent increase in solar activity.

Marty, KB0QZ, in Tulsa was tuning 10 meters at noon on Sunday, September 12 and heard no signals, not even any propagation beacons. He called CQ on 28.040 MHz CW and received a 599 report from LU4HK, who was also S9. The path distance was 5,094 miles. He continued to tune the band and call CQ through the afternoon with nothing else heard.

Page down in this article, “Nevada County Captures: Glorious sunrise” and page down for a great solar image in a local California newspaper.

Go to your favorite search engine and enter: mdpi: sunspot number and photon flux data. An interesting PDF will download.

At 2000 UTC on September 13 I (K7RA) called CQ on 15 meters on FT8 from my station in Seattle at CN87uq using a marginal end-fed wire antenna about 0.72 wavelength long, partially indoors. Typically I would see the map at pskreporter.info light up with many stations reporting my signal. But at that time only one station, WA1SXK in North Carolina (EM95lf) heard me, reporting –19 dB, and this continued through many attempts.

I switched to 17 meters and saw typical reports from stations in the midwest and east coast, 1500 – 2400 miles out.

I checked for flare activity and anything else unusual, but saw nothing. But solar flux and sunspot numbers were declining, after reaching a high several days earlier. Perhaps the MUF for this path at that time was below 15 meters.

Sunspot numbers for September 9 – 15 were 124, 99, 93, 47, 32, 13, and 0, with a mean of 58.3. The 10.7-centimeter flux was 99.7, 96.3, 91.8, 87.7, 83.3, 78.1, and 75.2, with a mean of 87.4. Estimated planetary A indices were 6, 9, 7, 6, 9, 6, and 6, with a mean of 7. Middle latitude A index was 7, 9, 8, 6, 7, 5, and 6, with a mean of 6.9.

For more information concerning radio propagation, visit the ARRL Technical Information Service, read “What the Numbers Mean…,” and check out this propagation page.

A propagation bulletin archive is available. For customizable propagation charts, visit the VOACAP Online for Ham Radio website.

Instructions for starting or ending email distribution of ARRL bulletins are on the ARRL website.

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