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The K7RA Solar Update


Another week and still no sunspots. The 3-month moving average for daily sunspot numbers that we began reporting toward the end of Solar Cycle 23 seemed to retrospectively suggest that solar minimum occurred last fall. The daily average for the 3-month period centered on last October was nearly 3 -- or 2.967 to split some hairs. This is an average of the 91 daily sunspot numbers from September 1-November 30.

Following that low, November was 6.85; from December 2007-April 2008, the 3-month average drifted from 8.14-8.89. With remaining Solar Cycle 23 spots becoming increasingly rare -- and barely any Solar Cycle 24 spots -- this suggested solar activity was stalling out. Then, at the end of June, a further decline when the 3-month average centered on May dropped to 5.04.

Sunspot numbers for July 3-9 were 0, 0, 0, 0, 0, 0 and 0 with a mean of 0. The 10.7 cm flux was 65.5, 65.4, 65.1, 66.1, 65.5, 65.5 and 66 with a mean of 65.6. Estimated planetary A indices were 4, 4, 7, 4, 3, 2 and 4 with a mean of 7. Estimated mid-latitude A indices were 3, 3, 7, 5, 2, 1 and 3 with a mean of 3.4.

Randy Crews, W7TJ, of Spokane, Washington, has an interesting observation regarding a possible double-minimum between cycles: He was looking at some charts of past sunspot cycles in Gene Zimmerman's, W3ZZ, "World Above 50 MHz" column on pages 90-91 in the February 2008 issue of QST. Randy wrote, "I noted the average period from a Cycle's peak declining to its low is on average seven years. So, linking that to our current Cycle's progress, things get interesting: If you count from the first Cycle 23 peak (April or July 2000), we are at the eight year mark now, and past due; however, Cycle 23 had a second peak in November/December 2001. We have not yet reached the seven year mark if you count from peak #2. This would coincide perfectly with Ken's article. Interesting enough, the NOAA propagation charts predict this fall as being the real pickup."

When Randy mentions "Ken's article," he is referring to Dr Kenneth Tapping of the Dominion Radio Astrophysical Observatory (DRAO) in Penticton, British Columbia, the source of our daily 10.7 cm solar flux numbers. Following a widely circulated false quote attributed to Tapping, we made his notes on the cycle minimum available to anyone who sends a blank e-mail. That offer still stands, and to date more than 1100 copies have been dispatched to readers. Randy also mentions "NOAA propagation charts," but I suspect he means tables of predicted smoothed sunspot numbers. Those can be found here and on page 8 here.

So what do zero sunspots mean for HF propagation in mid-July? From my home in Seattle, the path to Japan has a Maximum Usable Frequency (MUF) that varies from a low of 13.1 MHz at 1630 UTC to a maximum of 16.8 MHz at 0530 UTC. To Hawaii, the lowest MUF is 11.3 MHz at 1200UTC to highest of 17.2 MHz at 0500 UTC. A further example is Texas to Brazil, with MUF ranging from 6.4 MHz at 0900 UTC to 20.8 MHz at 0200 UTC. That is all a very narrow range. With an average sunspot number of 100 for that Texas to Brazil path, a low of 18.2 MHz at 0900 UTC to 29.7 MHz at 1730 UTC and 2100 UTC is enough to support good 10 meter propagation.

Sporadic E propagation on 10 and 6 meters generated more mail this week.

Jeff Hartley, N8II of Shepherdstown, West Virginia, sent the following report on July 4. "Just a quick note to mention the 6 meter conditions on June 27-28. Around 2000 UTC on June 27, the Es opening began on 50 MHz here. I had very bad luck getting any Europeans to answer my CQ and my Euro footprint was pretty small to northern France, Netherlands, southern England and Ireland. I worked a total of about 6 stations in those countries. There were a few weak signals persisting past 2200 UTC (I heard MM0AMW). Most all of the activity was on CW. Saturday morning, June 28, I turned on the radio to find loud Italians all over the 50.080-50.100 segment at 1320 UTC. I worked quite a few in the I-4 call areas. There was a loud IZ1 who couldn't hear 3/4 of the stations calling him, and I heard a weak I7. I worked a total of about 15 stations over 45 minutes or so, and again there was surprisingly much more activity on CW than phone. This time, I did get a few CQs answered. I also heard S57RR, 9A1CCY and a 9A6, but the pile-ups were big and unruly on the first two guys. K1HTV near DC missed the S5 due to two callers out of turn. I would have persisted and not let the 'breakers' in if I were the DX."

Joaquin Montoya, EA2CCG, of Oteiza, Spain, says on June 30 there was a nice 10 meter opening to the Caribbean with Martinique booming in. He worked his first 6 meter sporadic E skip on July 2, with a dozen European stations out to about 1500 km. They were all from Poland, Denmark and Germany.

Russ Hunt, WQ3X, on Kitner Hill in Upper Black Eddy, Pennsylvania, mentioned that on July 6 that there were great 6 and 10 meter openings on June 27-28. He wrote, "On June 27, I worked the following stations on 10 meters SSB: 2337 LA0EM, 2340 4O3A (59+), 2343 EA1ALE, 2348 MW0JZE and 2350 MM0SJH (59+). Many of these stations said they had to go to bed but didn't want to! The band remained open the following morning and most of the day. On June 28, I worked two stations on 10 meters CW: 2152 EA7UU and 2156 IT9EJW (he called me after I finished with EA7UU and we went up one for a short exchange). It was amazing and really lifted my spirits. I was running an FT-1000MP with Collins 30S-1 amp at about 1 KW output into a 5 element monobander (105-BA) at 50 feet. My elevation here on Kintner Hill is about 600 feet." Russ heard about the 6 meter reports on a spotting network.

Jon Jones, N0JK, of Wichita, Kansas, had a July 4 report: "I worked TO5E (St Barts) 6 meter DXpedition on July 4. I was operating portable in the Flint Hills of Eastern Kansas from a hilltop with a 2 element Yagi and 100 W. I first heard TO5E on 50.108 around 1350 UTC. Weak residual almost like scatter. He gradually built up and I heard them work K0RU in EM28 on CW. Then I got through. Some fading signals, and I worried TO5E would drop out before finishing the contact! But got my 559 fine and they confirmed. TO5E continued to build, and at 1410 UTC he was solid on SSB. By 1425 UTC, TO5E peaked well over S-9. I also worked KP4SQ and Julio, NP3CW, at 1430 UTC. KP4SQ had a bigger pileup on him than TO5E did. Go figure! I called Larry, N0LL, and my wife, N0HKT, on my cell phone and let them hear TO5E. This was the first decent Caribbean E-skip opening I have caught this year. The opening acted more like F2 than E-skip, in that I heard no stateside signals at first. Only the Caribbean DX. Later the K4MHZ/b FM25 appeared. TO5E has had some other good openings to the USA, including July 1 when they worked all the way to VE7."

Greg Andracke, W2BEE, of Pine Plains, New York, wrote: "After about 52 years as a CW operator on the lower HF bands, the mention yet again in your bulletin of the activity on 6 meters prompted me to get the radio out of the closet and hook it to an HF ground-mounted vertical to see what would happen on 6. With a match in the 2:1 range and about 100 W out, I worked N5GW, W5DNT and K5FA in short order on July 7 from FN31ew at about 0045 UTC. Enough fun to get me to eventually put a Yagi on this band!"

Scott Avery, WA6LIE, of Salinas, California, seemed to be very excited when he wrote to us on July 7. Why? More six meter propagation, of course! Scott is in grid square CM96 and on July 7, he said 6 meters was "HOT!" from 2300-0500 UTC. He was working East Coast stations from Pennsylvania to Florida, "and everywhere in between." He worked many CN85-87 (Western Oregon and Washington) and had many pileups from CN85 (Portland, Oregon). For 6 hours, after swinging the beam to the east, he worked many Upper Midwest and New England stations in EN and FN. He didn't hear Japan, but he noticed Chip, K7JA, working Japan around 0000 UTC on 6 meters CW. While writing the e-mail, he said he was working K5HCT in Odessa, Texas at 0535 UTC. At 0610 UTC, he wrote to say 6 meters was still open and he was having a long QSO with KJ6AP in Vancouver, Washington, but it was time to go to bed.

WA6LIE has set up his station to be operated remotely by others. Details can be found here.

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 in The ARRL Letter. 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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