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SEATTLE, WA, Nov 27, 2006 -- This "Solar Update" is being released on an irregular schedule because of the Thanksgiving holiday and to report the full week of solar and geomagnetic data, including updated November 16-22 numbers.
As predicted, a solar wind stream activated geomagnetic indices over the weekend during the CQ Worldwide DX Contest (CW). Conditions weren't bad though, just unsettled at higher latitudes. The mid-latitude A index for November 24-26 was only 10, 10 and 9, but the planetary A index was 21, 15 and 15 and the high-latitude college A index was 32, 21 and 17. A check of activity over the weekend showed plenty of 10-meter reports, so perhaps there will be propagation for the ARRL 10 Meter Contest December 9-10, even as we veer toward the bottom of the sunspot cycle.
We saw three days of zero sunspots, November 22-24, but a new sunspot 926 appeared over the weekend. Sunspot numbers should be above 12 over the next few days, with low geomagnetic activity. The US Air Force predicts solar flux around 80 for the next 10 days, and planetary A index around 5 until December 6. The next recurring coronal hole expected to push up the geomagnetic indicators should have maximum effect around December 7 -- couple of days before the ARRL 10 Meter Contest.
Ken Kuzenski, AC4RD, of Raleigh, North Carolina, has been off the air for the past few years, but a few weeks ago he began using PSK31 on 12 meters with 30 W and a low horizontal loop. He writes that a couple of weeks ago he was working a station in California around 2200-2300 UTC, and when the other station dropped out, he assumed the band was closing but then was called by a ZL station. "I didn't know to be surprised, not being familiar with the state of propagation lately," he said.
For More Information
For more information concerning propagation and an explanation of the numbers used in this bulletin see the ARRL Technical Information Service Propagation page and the article "The Sun, the Earth, the Ionosphere: What the Numbers Mean, and Propagation Predictions," by Carl Luetzelschwab, K9LA. An archive of past bulletins is on the ARRL Web site. The propagation charts that formerly appeared in QST now are available on the QST Propagation Charts page on the ARRL Web site.
Weekly Sunspot Numbers
Sunspot numbers for November 16 through 22 were 42, 38, 39, 38, 33, 11 and 0, with a mean of 28.7. The 10.7 cm flux was 94.1, 89.5, 88.8, 84.9, 80.5, 77.5, and 76.5, with a mean of 84.5. Estimated planetary A indices were 8, 5, 2, 3, 2, 1 and 4, with a mean of 3.6. Estimated mid-latitude A indices were 5, 3, 0, 2, 1, 1 and 3, with a mean of 2.1.
Amateur solar observer Tad Cook, K7RA, 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. Readers may contact the author via e-mail.
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