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The K7RA Solar Update


There was another decline in sunspot activity this week, but based on activity over the past few days, combined with the projected solar flux values, it is making a steady recovery. The sunspot numbers for October 4-10 were 56, 55, 39, 37, 41, 63 and 71, with a mean of 51.7. The 10.7 cm flux was 109.5, 106.2, 98.8, 98.1, 103.4, 106.2 and 112, with a mean of 104.9. The estimated planetary A indices were 3, 4, 6, 5, 35, 42 and 10, with a mean of 15. The estimated mid-latitude A indices were 3, 3, 5, 4, 21, 32 and 6, with a mean of 10.6.

The average daily sunspot numbers dropped from 73 to 51.7, a difference of 21.3 points; however, the past three days saw sunspot numbers higher (63, 71 and 82) -- than the average -- and climbing. The average daily solar flux numbers were off 23.8 points, to 104.9, and like the sunspot figures, the past three days saw solar flux values (106.2, 112 and 116.6) higher than the average for the week. This is a good indicator of the rising activity.

The predicted solar flux from the Thursday, October 11 NOAA/USAF forecast is 115 on October 12-13, 120 on October 14-17, then rising to125, 130, 150 and 145 on October 18-21, and peaking at140 on October 22-23. It’s down to 135 on October 24-27 and 130, 125, 120 and 115 through the last day of October. The solar flux is then predicted to dip below 100 on November 4-8, and then peak again at 145, 150 and 145 on November 15-17.

The predicted planetary A index for October 12-17 is 5, 5, 12, 12, 10 and 8, then back down to 5 on October 18-November 3, then 18, 20, 12 and 8 on November 4-7. Look for it to go down to 5 on November 8-10, then 8, 12 and 10 on November 11-13, and 5 after that through the end of the 45 day forecast period.

The most geomagnetic activity during the past week was on October 8-9, with the planetary A index at 35 and 42, the mid-latitude A index at 21 and 32, and the high latitude college A index at 66 and 54. This activity was triggered by a coronal mass ejection on October 8. The predicted rise in planetary A index to 12 on October 14-15 is due to a solar wind that is spewing from a coronal hole that should rotate into a geo-effective position during that time.

John King, EI2HVB, said that on October 10 he worked W1AW on 20 meter CW using only 2 W into a sloping V dipole. This was right after seeing aurora from his location in Ireland for several nights in a row. Of course, unlike here on the West Coast, a path from W1AW to Ireland is not anything near a polar route, so it would not be as affected by geomagnetic unrest as a contact to Europe from the West Coast would be. In Seattle, my bearing to Letterkenny -- John’s town -- would be 35.7 degrees -- close to the auroral zone -- and his return path would be at 316.9 degrees. But from W1AW, short path would be toward 49.2 degrees, and return path is 280.4, further away from the polar path.

Dean Lewis, W9WGV, of Palatine, Illinois wrote: “While working county after county in the California QSO Party on the low end of 10 meters on Saturday, October 6, I heard PY2XC calling CQ DX. I had a friendly exchange with Carlos; 559 signals both ways, no fading signals. He was running 200 W to a dipole; due to outside antenna restrictions I run a 10 W max transceiver  into an end-fed 65 foot wire (halfwave on 40 meters) indoors, along the upstairs ceiling (I’ve had the most supportive wife in hamdom for 42 yrs). It resonates at a low SWR on 40, 20, 15 and 10 meters without a tuner. The distance from my location to Carolos is 5248 miles. A half hour later, his signal was S9+.”

I received some interesting e-mails this week from a ham who has one of those FCC experimental licenses that allow him to operate below the AM broadcast band to test antennas, radios and propagation. I was about to present some of his observations here in the bulletin, but just now noticed that at the very top of his first e-mail was a statement about “this is not intended for publication.” That’s unfortunate, as he wants to attract others to do what he is doing, but now I feel restrained from quoting our correspondence. If you send me an e-mail, normally you can assume that I might quote you, as well as make edits for brevity and readability (as will my editor).

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.




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