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The K7RA Solar Update


The average daily solar flux declined this week more than 36 points compared to last week, to 24.6. Our reporting week -- which ran until November 24 -- showed the daily sunspot number declining from 40 to 11, but on November 25 the sunspot number rose to 22. Sunspot numbers for November 18-24 were 40, 37, 24, 25, 23, 12 and 11, with a mean of 24.6. The 10.7 cm flux was 86.5, 84, 79.8, 77.6, 74.8, 75.3 and 75.8, with a mean of 79.1. The estimated planetary A indices were 5, 2, 2, 3, 4, 8 and 4, with a mean of 4. The estimated mid-latitude A indices were 4, 2, 2, 2, 4, 7 and 3, with a mean of 3.4.

Sunspot group 1125 disappeared on November 17, and on November 20, sunspot group 1124 was gone after 10 days of visibility. Group1126 was gone on November 23 (after 11 days), and 1127 is still visible after 10 days. On November 25, new sunspot group 1128 arose near the eastern horizon; it may just provide some needed propagation juice for this weekend’s CQ World Wide CW DX Contest.

Solar flux during this week went from a high of 86.5 to 74.8; the predicted solar flux for November 26-30 is 78, 78, 79, 80 and 80. Solar flux is predicted at 78 for December 1-3, then 85 on December 4-11 and 90 on December 12-14. Perhaps this bodes well for the ARRL 10 Meter Contest, December 11-12. That contest is also during a time when ionization from meteors may enhance 10 meter propagation.

The solar flux forecast is from NOAA and USAF, and they say planetary A index should be stable for the next couple of weeks, with the index at 5 for November 26-December 10. Geophysical Institute Prague has a different outlook: They say that for the next week, look for quiet conditions November 26, quiet-to-unsettled November 27, unsettled November 28, quiet-to-unsettled November 29 and quiet November 30 through December 2.

This weekend, the STEREO mission will achieve 97.3 percent coverage. This means that only 2.7 percent of the Sun is now not visible to us, and that is in the area on the side of the Sun facing away from Earth. STEREO will achieve 98.7 percent coverage by the end of this year and should finally achieve 100 percent coverage some time on February 6, 2011.

Things are still looking up in terms of increasing sunspot activity: The first 25 days in November had an average daily sunspot number of 38, compared to 18, 23.1, 28.2, 35.7 and 35 for June through October. If this average continues through the next five days, November will have the highest monthly average of daily sunspot numbers since May 2006, when it was 39.6.

A brief report from Pete Heins, N6ZE, of Thousand Oaks, California (DM04): On November 19 at 0056 UTC with 100 W and a vertical, he worked VP8LP in the Falkland Islands with S5 reports both directions. VP8LP was working mostly W6, W7 and VE7. Click here for details on Pete’s VHF exploits.

Larry Jones, K5ZRK, of Sandersville, Mississippi, lives on the edge of the Tallahalla Swamp. He wrote: “I operate only 30 and 60 meters. I have a separate receive antenna on 60 meters. The morning of November 17 -- while in QSO with Les, KG4QZV (in Rome, Georgia, about 300 miles away) -- and after Les un-keyed, I heard a very distinct echo off his signal. We were on 5.3465 MHz. The echo had less signal strength than Les’s originating signal. I have only heard this happen once before on 60 meters and I chase the gray line on this band every day. Is this long path or diversity reception? I might also note that the gray line was very productive this same morning.”

Hard to say what was causing that echo, but at 186,000 miles per second, a 30 ms echo could emerge if the signal traveled 2700 miles, bounced and covered the same distance back. It seems unlikely to be long path, but perhaps that gray line was propagating that signal a long distance and propagating the echo back. Read more about Larry’s QRP activity on 30 and 60 meters here.

Some readers who read this bulletin last week on the ARRL Web site had trouble linking to the pdf provided by Dean Straw, N6BV. Try the text version and right-click and save via the link provided for the pdf of “Seeing the HF Propagation Big Picture.”

Carl Luetzelschwab, K9LA, has a piece on HF circular polarization in his propagation column in the current issue of World Radio.



Thanks to my editor, S. Khrystyne Keane, K1SFA, for posting this bulletin to the ARRL Web site from her home on Friday, November 26. The e-mail version won’t propagate until Monday, November 29.

All times, unless otherwise noted, are UTC.



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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