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The K7RA Solar Update


The past week had one 0 sunspot day -- Thursday, January 27. Even though the activity came right back, the average daily sunspot number for the week fell more than 12 points to 20.1, and the average daily solar flux declined 2.7 points to 80.8. After the sunspot numbers of 21, 22 and 22 on Monday, Tuesday and Wednesday, the sunspot number rose to 32 on Thursday, February 3. Sunspot numbers for January 27-February 2 were 0, 27, 27, 22, 21, 22 and 22, with a mean of 20.1. The 10.7 cm flux was 80.5, 80.6, 81.4, 82.6, 81.3, 79.9 and 79.2, with a mean of 80.8. The estimated planetary A indices were 3, 4, 4, 1, 5, 8 and 5, with a mean of 4.3. The estimated mid-latitude A indices were 2, 4, 3, 2, 4, 7 and 5, with a mean of 3.9

The predicted solar flux values for the next week were below the average for the previous seven days when reported on Thursday in The ARRL Letter, but the forecast has improved since then. The solar flux values forecast by NOAA/USAF are 80 on February 4-8, 78 on February 9-10, then 80, 80, 82, 81, 81, 82 and 88 on February 11-17. The predicted A index on February 4-5 is 10 and 8, followed by 5 on February 6-28. Geophysical Institute Prague sees unsettled to active conditions for today, February 4, unsettled February 5, quiet on February 6-8, quiet to unsettled February 9 and unsettled conditions return on February 10.

On Friday, the STEREO craft are now very, very close to perfect alignment for 100 percent coverage of the Sun. On February 4 at 1430 UTC, STEREO has achieved 99.899 percent coverage, the missing sector now a tiny slit near the 180 degree meridian. By 2300 UTC on February 5, STEREO coverage should be 99.917 percent; it should reach 100 percent coverage shortly after 0926 UTC on Sunday, February 6. This is when the STEREO satellites begin their move into the position where the gap closes on our Sun’s far side and begins to open on the Earth side. Images from the NASA Solar Dynamics Observatory will begin to fill the new gap along the Sun’s 0 degree meridian, the side facing us. See the SDO page here for almost-live images. They have a nice gallery of recent images here.

We have some new 3-month moving averages for sunspot numbers. This solar cycle appears stalled, although numbers are much higher than a year ago. They are back up to the numbers seen on the downside of Solar Cycle 23 during late 2005 and early 2006. Our 3-month moving average takes the sum of all sunspot numbers for three calendar months, divides the total by number of days and reports it as for the center month. The next month’s average drops the oldest month and adds data from a new month. So the latest moving average is centered on December 2010, and takes the arithmetic average of all the sunspot numbers over the 92 days from November 1 through January 31. The total was 2765 and the average centered on December, 2010 was 30.1.

Here are the moving averages for the last four years, starting with the numbers centered on January 2007.

  • The 2007 averages were 22.7, 18.5, 11.2, 12.2, 15.8, 18.7, 15.4, 10.2, 5.4, 3, 6.9 and 8.1.
  • The 2008 averages were 8.5, 8.4, 8.4, 8.9, 5, 3.7, 2, 1.1, 2.5, 4.5, 4.4, and 3.6.
  • The 2009 averages were 2.2, 2, 1.5, 2, 4, 5.2, 4, 4, 4.6, 7.1, 10.2 and 15.
  • The 2010 averages were 22.4, 25.7, 22.3, 18.5, 16.4, 20.4, 23.2, 28.9, 33, 35.6, 31 and 30.1.

I believe it was 20 years ago this week -- early February 1991 -- when I took over writing this bulletin (without realizing it at first) from Ed Tilton, W1HDQ, who had written it for so many years that I’ve found no one who recalls when it started. I remember copying his bulletin as a 13-14 year old on CW in 1966 from W1AW. The propagation bulletin came out on Sunday, January 7 or February 3, saying that W1HDQ was ill and there would be no propagation bulletin from W1AW that week. Until then I had my 20 meter Yagi left pointed toward 81 degrees (short path from me to W1AW) and my Drake TR7 left on the 20 meter W1AW RTTY bulletin frequency. I copied ARRL bulletins unattended on FEC AMTOR (a serial mode with redundancy and parity bits) and after cleaning them up, I would put them out on the packet radio network via VHF. At that time, the coast-to-coast packet network was not well connected, and it would often take several days for ARRL bulletins to reach the West Coast. I had been doing the same thing with the VK2SG RTTY DX Bulletin.

Around the time Ed’s illness was announced, I noticed a dramatic rise in solar indices. The daily solar flux I copied from WWV on January 24-31, 1991 was 214, 267, 283, 303, 327, 353, 353 and 357. Solar Cycle 22 was declining, and by the way, I cannot find any evidence that there have been solar flux values anywhere near this high at any time in the past 20 years. I thought it was a shame that the ARRL wasn’t reporting this in a bulletin, so I called ARRL Headquarters to see if the propagation bulletin would be returning the following week. The person I talked to said he didn’t think so. Then I called Ed Tilton at his home in Florida.

Ed’s wife answered my call. She told me that he was too ill to speak with me on the phone. She asked why I was calling, and when I told her, she said, “What are the numbers?” When I told her the solar flux was above 350, she quickly said, “Oh, he’ll want to hear this!” After a long silence, Ed’s voice was on the line. He was thrilled by the news of the solar activity, but said he didn’t know when he would be able to write the next bulletin.

I called ARRL Headquarters again, and told the person I had spoken with that something had to be done, because this news was just too big. Maybe I could give him the information and someone at headquarters could write an interim propagation bulletin until Ed recovered. The person I spoke with said he had no idea who would do this, so I volunteered that I was familiar with Ed’s style because I had been copying the bulletin and editing out errors for redistribution via the packet network.

I was asked to write something up and e-mail it in. Yes, I had email back in 1991, actually since the 1980s, due to the generosity of WA6SWR, who gave me an e-mail account and Usenet access so I could read and post to It was a UNIX shell account at a company he owned. Remember, this was just a few weeks before Tim Berners-Lee released the first web browser and HTML editor, so there was no worldwide web.

They liked the first bulletin and asked if I could write another the following week. I never intended to replace Ed or even thought I was qualified, and unfortunately, Ed never recovered enough to write another bulletin and he passed away more than six years later. Soon I changed the release to Friday instead of Sunday evening, so we could report propagation news just before each weekend.

It’s hard to believe it has been 20 years, but one week rolls into the next and time flies. I’ve learned a little about propagation since then, mostly from a helpful pool of patient, generous and knowledgeable readers.

David Moore, who is not a ham, sent a press release from the National Science Foundation about a new large-scale space weather model.  Read about it here and see the hi-res image here. Also see the web page for the Center for Integrated Space Weather Modeling here.

Tamas Holman, HA5PT, in Budapest sent in this interesting report: “On the morning of January 30, I was chasing DX on 17 meters and heard UT7UJ calling CQ. Though Ukraine is not DX from Budapest, I still needed Ukraine confirmation on 17 meters and the VE7CC DX cluster reported he is an LoTW member so I called right away. Dim hardly copied my 100 W and after the fourth attempt, he was still asking QRZs. Because his signal came to me on multiple paths with echoes, I routinely switched my antenna direction to LP and suddenly his weak signals became strong and we both got into our logs with 599. After our QSO, I recorded his CQ changing my antenna direction in the middle, the first half is LP and the second SP direction. Looking at the audio signals, even the delay between the two paths can easily be measured and it shows that the 0.13 sec was just needed to cover the 39,000 km distance through long path. Though when I called Dim, I did not want to make a long DX contact, it turned out that I reached my ODX QSO in my life”. ODX means his best long distance QSO.

Jeff Hartley, N8II, of Shepherdstown, West Virginia, reported this on February 1: “Low band conditions were fairly good over the past few days. I didn’t take part in the CQ WW 160 contest. The high bands have really been poor with very marginal Western Europe only on Sunday the January 30; January 29 was a bit better. Taking a look at the ARRL predictions for January, they are overly optimistic on MUF. We have had very few openings to the West Coast on 10 meters; the charts show about 3-1/2 hours starting 1730. Even South America -- which shows an even longer opening -- is not present most days on 10 meters. I think we all had expected better openings on 15 and 10 meters by now. We had some really nice 10 meter openings February 2010 and October 2010, but December and January have been pretty poor.”

All times listed are UTC, unless otherwise noted.

Amateur solar observer Tad Cook, K7RA, of Seattle, Washington, provides this weekly report on solar conditions and propagation. This report also is available via W1AW every Friday, and an abbreviated version appears each Thursday in The ARRL Letter. You can find a guide to articles and programs concerning propagation here. Check here for a detailed explanation of the numbers used in this bulletin. An archive of past propagation bulletins can be found here. You can find monthly propagation charts between four USA regions and 12 overseas locations here. Readers may contact the author via e-mail.



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