Register Account

Login Help


The K7RA Solar Update


Conditions were quieter again this week. Average daily sunspot numbers declined from 77 to 69, and average daily solar flux was off by 9.5 points to 106.9, when compared to the previous seven days, August 22-28.

Predicted solar flux for the near term is 105 on September 6-10, 100 on September 11-12, 110 on September 13, 120 on September 14-15, 115 on September 16-17, 110 on September 18, 105 on September 19-20, 110 on September 21-22, 105 on September 23-24, and 100 on September 25-28. It then is expected to reach a minor peak of 115 on October 4-5, then 120 on October 9-12.

These predictions come from a 45-day forecast. Yesterday, September 5, the solar flux was 110.1. The first prediction for that date in this series pegged it at 135, which maintained from July 22-28, then 105 on July 29 through August 4, 115 on August 5-11, 105 on August 12-18, 110 on August 19-28, 112 on August 29, 115 on August 30, 118 on August 31, 112 on September 1-2, and then they nailed it at 110 again on September 3-4. Note that these aren’t the flux readings on those dates. They are the predicted values for September 5, as they varied from day to day in the daily forecast for the previous 45 days.

You can see those daily forecasts here:

The planetary A index is in the same forecast. The latest has predicted planetary A index at 5 on September 6-8, 10 on September 9-10, 12 on September 11, 8 on September 12-14, 5 on September 15-16, then 12, 18 and 15 on September 17-19, 5 on September 20-22, and 8 on September 23-24.

The autumnal equinox (September 22 at 2044 UTC) is a little over two weeks away. Fall is always a great time for HF DX, when the sun casts an even glow over our northern and southern hemispheres. Although solar activity is weak, if this is cycle 24’s peak, now may be the best time for enjoying HF propagation for some years to come. Or the sun could fool us again. Remember that day-to-day variations in solar activity can swing wildly above and below any predicted smoothed or averaged sunspot or solar flux number. But we haven’t seen much of that lately.

F.K. Janda, OK1HH, offers his geomagnetic forecast. Mostly quiet conditions September 6-7, quiet to unsettled September 8, quiet to active September 9, quiet to unsettled September 10, quiet to active September 11, active to disturbed September 12, quiet September 13, mostly quiet September 14, quiet September 15-16, quiet to active September 17, active to disturbed September 18, quiet to unsettled September 19-21, mostly quiet September 22, quiet to active September 23, quiet September 24-25, mostly quiet September 26, active to disturbed September 27, quiet to active September 28, mostly quiet September 29, quiet September 30, quiet to active October 1, and quiet on October 2.

Last week’s bulletin mentioned average sunspot numbers, but we were missing two days of data (from August 30-31) to get the complete average.  As it turns out, those two days had low enough sunspot numbers that it actually dragged the 3-month moving average and the monthly average for August lower.

So the three month moving averages of sunspot numbers for periods ending in January through August 2013 were 82.8, 73.6, 80.7, 85.2, 106.4, 106.4, 97.5 and 85.6. The average daily sunspot number for the month of August was 90.2, up from 80.2 and 86.2 in June and July.

Thanks so much to Scott Bidstrup, TI3/W7RI in Costa Rica who sent a link to a fascinating article in Phys.Org News and Astronomy and Astrophysics about yet another failure to replicate earlier studies claiming a correlation between planetary positions and solar activity. In this case, the authors found several serious statistical errors in the earlier analysis. Read the article and abstract at and Note that for a limited time, the full text of the paper is available for free by clicking on the Register Now button on that last page.

NASA has an updated prediction for sunspot cycle 24, and like last month, they predict the peak for summer 2013 (that’s now!) but they have downgraded the expected smoothed sunspot number from 67 to 66.  Read it and weep, at They do not have any archive of past predictions, but never fear, I have been keeping careful track.

A year ago, they sounded an optimistic note, when the September 2012 update changed from a peak of 60 in Spring 2013 to a peak of 76 in Fall 2013.

A month later in October it changed to a peak of 75 in Fall 2013, then in November it dropped to 73 in Fall 2013. In December the number was revised to 72, and in January 2013 the predicted peak was changed to 69. February’s prediction was unchanged, then March 2013 revised the peak down again to 66. April and May were unchanged, and in June the prediction was revised upward from a peak of 66 in Fall 2013 to a peak of 67 in Summer 2013. July and August were unchanged, and now we have the number back down a point in again to 66 in September.

Lawrence, GJ3RAX, sent us more nice VHF reports from the British Isles. The first, in an email on August 30:

“Sporadic E openings on 6 m are starting to become quite rare at this time of year. I thought that the one on August 12 was going to be the last one. I had some nice QSOs that day with IS0, OE1, F4, HA5, OK2 and EA6. After that I did not catch any more until last Wednesday August 28 when 6 m opened again. I then had 8 QSOs into Germany, 3 into OK, one each with OE and SP. Those were between 1430-1545 GMT. A friend of mine told me afterwards that he was also getting some good ones on 4 m which I did not bother to check. I would probably have missed the opening if I was not using my IC-756 Pro 2 which I had left on 6 m with the panoramic display visible when I glanced at it. Any signals that are strong enough to work with SSB show up well. I do not use any of the other modes.

“The next two days also showed propagation at times. On August 29 I had one QSO with CT1EUB at 1200 GMT. On August 30 I was in QSO with EA7/G0WHX at 1030 GMT. The band opened again later after a QSO with F6HRP, who is relatively local, at 1720 GMT followed by CT1FJC.

“I have not had any QSOs on the HF bands recently. I listen at times but rarely hear anything on the bands from 17 m to 10 m which seems very strange considering that we are at about the peak of this solar cycle. I used to keep skeds on 17 m with friends in the USA and Canada. My antenna on those bands is an old Cushcraft R5 at only 10 feet above the ground. On 20 m I usually hear some European activity but often without hearing anyone speaking English. Even 40 m seems quieter that it used to be as I used to use it as a chat band during daytime with those in other parts of the British Isles. I have not been on 80 m recently, even at night, and it seems to be years since I used Top Band.

“Thanks for mentioning our VHF and Microwave groups on Yahoo. After that both gained new members from the USA. The VHFandUHF group is now up to 125 members.

73, Lawrence  GJ3RAX”

And on September 6, another report:

“Every Tuesday evening there is a short VHF contest, organised by the RSGB, on a different band each week. They run from 8 pm to 10:30 pm local time, now still BST. This week, on September 3, it was on 2 m and conditions were interesting. I only come on for part of the contest each week as I never take them seriously from the competitive point of view. This time I started shortly after 9 pm and started with a QSO with an EI station, then G, GW and GD. My QSO with GD8EXI was my best DX that evening at about 356 miles, according to QRZ. After that it was all G stations apart from exchanging notes with some of the others here in GJ. One of them had worked up to GM but that might have been on CW. I only use SSB.

“I had heard reports of some of the more northern stations working down to EA8. I did hear weak signal from the north of England, towards the end of the contest, working an EA8 so I turned my beam south but did not hear anything.

"The contest next Tuesday evening will be on 70 cms.

"Wednesday morning, September 4, it was still good on 2 m and I worked 4 stations in the south of EI where it was mostly a sea path between us apart from a bit of Cornwall to get over. They were between 320 and 370 miles away. I also worked into the south of GW and a French station at about 200 miles near Paris. One of the EI stations wanted to try 70 cms as well although he knew that he had an antenna problem. We made it although it was rather marginal. Later he was able to fix the problem with his antenna so we tried again in the evening but nothing was heard. The region of high pressure had moved and it was raining at his end.

“I have heard nothing on 6 m since the QSOs on August 30 so it looks as if the Sporadic E season is over and we are getting into the tropo season.

“There is the 144 MHz Trophy Contest this weekend on Saturday and Sunday. I am not expecting conditions to be good for that one but I will be on for some of the time but not while I am watching the F1 motor racing from Monza.”

Thank you Lawrence.

Not hearing anything on 10 meters? Check out Tony’s 10 Metre Band Report from G4CJC:

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

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 August 29 through September 4 were 55, 62, 60, 71, 84, 74, and 77, with a mean of 69. 10.7 cm flux was 108.8, 107.5, 107.5, 103.8, 105.6, 106, and 109.3, with a mean of 106.9. Estimated planetary A indices were 3, 8, 11, 9, 10, 7, and 6, with a mean of 7.7. Estimated mid-latitude A indices were 4, 7, 11, 10, 11, 8, and 9, with a mean of 8.6.



Instragram     Facebook     Twitter     YouTube     LinkedIn