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The K7RA Solar Update


Average daily sunspot numbers this week moved from 101.7 to 113.4, while average daily solar flux changed from 111.8 to 130.5. The active day according to geomagnetic indicators was Wednesday, August 27, when the planetary A index reached 20. This was the result of a CME which created aurora at both north and south poles.

Predicted solar flux is 115 on August 29-31, 120 on September 1-2, then 110, 105, 110 and 120 on September 3-6, 125 on September 7-8, then 120, 125, and 130, on September 9-11, then 135, 130, 135, and 140 on September 12-15, then 145 on September 16-17, 140 on September 18-19, 135 on September 20-23, and 125 on September 24-25.

Predicted planetary A index is 10, 8, 12 and 18 on August 29 through September 1, 5 on September 2-5, 8 on September 6-7, 12 on September 8, 5 on September 9-12, 8 on September 13, and 5 on September 14-23.

OK1HH predicts quiet to active geomagnetic conditions August 29, active to disturbed August 30, quiet to active August 31 through September 1, quiet September 2, quiet to unsettled September 3-4, quiet September 5, mostly quiet September 6, quiet to unsettled September 7-8, quiet September 9-12, quiet to unsettled September 13, active to disturbed September 14-15, mostly quiet September 16-17, quiet September 18-21, quiet to active September 22 and active to disturbed September 23.

Costas Krallis, SV1XV, of Athens, Greece wrote about the numbers at the end of last week’s bulletin: “Now something is wrong about the mean values. How can the average of seven numbers, all of them lower than 120, be 138.8? And how can the average of seven numbers, none of them lower than 4, be 3.7?”

Costas is correct, but how could I be so wrong? To correct the record for last week’s bulletin, the average daily sunspot number for August 14-20 was 101.7, average solar flux was 111.8, average planetary A index was 6.7 and average mid-latitude A index was 7.1.

NOAA has a couple of new web pages they are rolling out. Check out the Space Weather Enthusiasts page at and the Data Access page at They also seek your comments at

Chip Sufitchi, N2YO/YO3FWC, sent a note about a Romanian propagation bulletin, which just published its five-hundredth edition. Chip wrote, “I wanted to inform you that the Weekly Propagation Bulletin hosted by the popular Romanian web site just released issue 500. One month ago the web site celebrated 10 years of continuous presence on the web by activating a special call sign (YR10RRO) and releasing a decennial award.

“The main section in the bulletin discusses some interesting propagation events occurring recently, including VHF/UHF if any, propagation facts during a recent major contest as reported by participants, or a forecast for the weekend's contest, if any significant one is scheduled. It does also inform readers about interesting articles with propagation/solar content found on the internet, or recent reported facts about the current solar cycle. The last section is a one week forecast for solar and geomagnetic activity, based on NOAA and IPS reports. Part of the bulletin is also the monthly propagation diagrams, generated on the first of each month, showing propagation in several directions centered on YO. The simulation is powered by VOAprop, a software tool created by G4ILO.”

The web site is here:

You can use Google Translate to read it in English. After clicking on the link to any of the bulletins, just copy the URL and paste it here in the box:

Of course you can select any language of your choice, and it at least gives you an idea of what the text is about.

Pete Corp, K2ARM, sent a lament about the end of the sporadic-E season. “I guess 6 meter E skip has disappeared for this season. July 21 and July 23 were the only European openings that I had. I used an overgrown dipole and 40 watts. I worked: G8BCG, G4FJK, ON4IQ, F6BLP, EI3KD, F8GGD, GM3SEK, G0JHC, F6AUS, F2DX, IK5MEJ, and Bert, F6HKA. It was nice while it lasted. Thanks for your reports. I sure hope HF conditions will get better soon.”

The overgrown dipole Pete uses is an Extended Double Zepp antenna. Do a Web search for “EDZ antenna” or “double extended zepp” or “extended double zepp” for more information on this old, interesting and effective antenna. You will discover many useful references. I first ran across this antenna in the 1970s when operating 2-meter FM simplex while parked near the top of Mount Sutro in San Francisco. I worked Art Childs, W6TYP (SK), who was using one oriented vertically on 2 meters, I think somewhere near Salinas, and later he sent me a diagram showing how it was built.

For more information concerning radio propagation, see the ARRL Technical Information Service at For an explanation of the numbers used in this bulletin, see An archive of past propagation bulletins is at More good information and tutorials on propagation are at

Sunspot numbers for August 21 through 27 were 128, 139, 124, 128, 112, 81, and 82, with a mean of 113.4. 10.7 cm flux was 128.3, 126.4, 132, 140.9, 135, 128, and 123, with a mean of 130.5. Estimated planetary A indices were 11, 4, 5, 4, 4, 4, and 20, with a mean of 7.4. Estimated mid-latitude A indices were 12, 4, 8, 5, 4, 5, and 19, with a mean of 8.1.




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