Solar activity retreated this week, with the average daily sunspot numbers off nearly 46 points -- about 35 percent -- to 83.1, while the average daily solar flux declined 18 points to 118.9. Sunspot numbers for September 6-12 were 112, 110, 70, 87, 62, 73 and 68, with a mean of 83.1. The 10.7 cm flux was 128, 133.4, 128.6, 123, 111.3, 105.1 and 102.6, with a mean of 118.9. The estimated planetary A indices were 11, 9, 8, 5, 4, 3 and 6, with a mean of 6.6. The estimated mid-latitude A indices were 12, 8, 7, 6, 4, 3, and 5, with a mean of 6.4.

Geomagnetic conditions were quieter, with the planetary and mid-latitude A index most days in the single digits. The average planetary A index declined from 14.1 to 6.6. The predicted daily solar flux is 100 on September 14-15, 95 on September 16-18, 98 on September 19, then 100, 95 and 100 on September 20-22, 110 on September 23-24, then 115, 125 and 130 on September 25-27, 140 on September 28 through October 1, 135 on October 2, and back down to 130 on October 3-5. The predicted planetary A index on September 14-17 is 7, 10, 15 and 10, then 5 on September 18-19, 8 on September 20-23, 5 on September 24-28, 10 on September 29, 5 on September 30 through October 2, 10 on October 3, and then 8 on October 4-5.

In VHF news, Rich Zwirko, K1HTV, of Amissville, Virginia, wrote to us on September 7, just before the ARRL VHF Contest last weekend: “I was pleasantly surprised to hear 6 meters open via trans-equatorial propagation to South America early Thursday evening, September 6. It started around 2240 and lasted about an hour at my FM18ap location in Virginia. In addition to working PY1RO, PY1NX and PY2XB on CW, I also heard, but did not work LU9EHF and PY1NS weakly on SSB. There is still some magic in the ‘Magic Band,’”.

Trans-Equatorial Propagation, or TEP, is a special kind of propagation across the equator. A good description of TEP comes from the Australian Government Radio and Space Weather Services.

Just before we put this bulletin to bed, K1HTV sent this: “Here is some additional info: During last weekend’s ARRL VHF contest, I heard three stations in Brazil on 6 meters. I worked PY5EW on SSB and PY2XB on CW. I also heard PY1RO weakly on SSB, but couldn’t work him. The 50 MHz TEP path between place in Virginia and the Brazilian stations started around 0005 on September 10 and lasted about 1 hour. Unfortunately, no other South American stations were heard. About 24 hours earlier in the contest, starting around 0000 on the September 9, we had a 90 minute E-s opening to W5 land, working stations in Oklahoma, Mississippi, Louisiana and Texas. Again, between 1330 and 1500 Sunday, there was a 6 meter E-s opening from here to Florida.”

Rich hopes for a double-peaked Solar Cycle 24, and that the solar activity will be enough to send the MUF on many paths above 50 MHz. Of course, in that case, instead of just Sporadic-E, we would see conventional F-layer ionospheric propagation.

John Jones, N0JK, of Lawrence, Kansas wrote: “The jump in solar activity coupled with some Sporadic-E on 6 meters created opportunities for some great propagation in the ARRL September VHF QSO Party (September 8-10). Both Saturday and Sunday had extended openings from New England, the Mid-Atlantic, Gulf Coast, Arizona and California to South America and the South Pacific. On Sunday, KA9CFD in EN40 spotted PY2XB at 0054 UTC September 10. And what may have been direct F2 from Florida to Ecuador Sunday occurred that afternoon. There was some E-s on Saturday evening from Kansas to Georgia, when W3GMT in EM92, WA4NJP in EM84 and W4IMD in EM84 were loud around 0035 UTC September 8.”

Jeff Hartley, N8II, in West Virginia wrote on September 9: “Today was a pretty good day on 15 and 10 meters, with the solar flux only in the 120s, definitely better than Saturday (September 8) with only South America on 10 meters. At 1451, I logged XV4Y (Vietnam) on 15 CW who was running a European pile up; I could not get through until he worked an N2 then started a ‘CQ NA only.’ Then I tuned 10 meters looking for Europe in the Worked All Europe Contest and heard a voice with polar flutter giving a contest report to an inaudible European station. I swung the Yagi north and 9W2VVH (Western Malaysia class B license) answered my SSB CQ at 1458. He gradually got stronger and went up to S7, running 100 W, once he beamed to USA. After a few more CQs, 9W2WWW answered and was equally as strong. 9W2AXV and 9W2NMX also answered CQs. It was in the 11 PM hour local time in 9W2 when the band peaked.

I didn’t work any other Asian stations, but after a dog walking break and lunch around 1700-1815, 10 opened to Europe with some weak and some loud signals from Central and Western Europe, but no propagation to Russia or Northern Europe. I worked 50 stations in 14 European countries in the WAE Contest, quite late in the day.”

Carl Luetzelschwab, K9LA, has some interesting comments about last fall not being the first peak of a double-peaked solar cycle. Last week, we mentioned that the NASA estimate has move the peak of Solar Cycle 24 from spring to fall 2013, with smoothed sunspot numbers higher than earlier forecasts.

Carl wrote: “The smoothed data (whether it be the smoothed sunspot number or the smoothed 10.7 cm solar flux) does not indicate a Cycle 24 peak in the fall of 2011. What happened was the Sun was very active for a couple months, and this was fortuitously in the fall months when the MUF is the highest in the northern hemisphere. The MUF reached more than 28 MHz, which gave us great worldwide 10 meter openings in the CQ World Wide DX Contests and the ARRL 10 Meter Contest. After that, solar activity waned, the MUF fell, and 10 meters wasn’t as good for the ARRL DX and CQ WPX Contests in the less-than-optimum months. Historically, a true peak would be followed by a definite dip in the smoothed indices prior to reaching another peak. Cycles 22 and 23 exhibited this classical behavior. But Solar Cycle 24 just had a leveling-off (as have other solar cycles on their ascent) before continuing its ascent. So we’re still waiting for the first peak of Solar Cycle 24. Whether it has a second peak is anyone’s guess.”

And finally, for an interesting video, visit the McMath-Pierce Solar Telescope on Kitt Peak National Observatory, located west of Tucson Arizona. While the McMath-Pierce telescope is located on Kitt Peak, it is part of the National Solar Observatory headquartered in Sunspot Arizona.

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 and 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.