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The K7RA Solar Update


Sunspot 1007 is still there, but probably rotating off the visible solar disk sometime today. This is the eighth sunspot of the new solar cycle -- and also the largest. Sunspot numbers for October 30-November 5 were 13, 16, 16, 17, 18, 14 and 11 with a mean of 15. The 10.7 cm flux was 66.8, 68.1, 66.7, 69.1, 69.5, 68 and 67.7 with a mean of 68. The estimated planetary A indices were 11, 6, 1, 2, 1, 1 and 0 with a mean of 3.1. The estimated mid-latitude A indices were 11, 5, 0, 2, 1, 1 and 0 with a mean of 2.9.

We've been posting a three-month moving average of sunspot numbers most months; now that October has passed, we can update the table of averages through the month of September. Last month, the three-month average centered on August was computed by adding together all of the daily sunspot numbers for July, August and September (102), then dividing that sum by the total number of days for those three months (92). The average centered on August is then approximately 1.1. For September, we did the same thing, only this time summing all daily sunspot numbers for August, September and October (230), then dividing by the number of days, yielding exactly 2.5.

Here are the three-month averages back through the summer of 2006:

Jun 06 28.9
Jul 06 23.3
Aug 06 23.5
Sep 06 21.2
Oct 06 24.1
Nov 06 23.1
Dec 06 27.3
Jan 07 22.7
Feb 07 18.5
Mar 07 11.2
Apr 07 12.2
May 07 15.8
Jun 07 18.7
Jul 07 15.4
Aug 07 10.2
Sep 07 5.4
Oct 07 3.0
Nov 07 6.9
Dec 07 8.1
Jan 08 8.5
Feb 08 8.4
Mar 08 8.4
Apr 08 8.9
May 08 5.0
Jun 08 3.7
Jul 08 2.0
Aug 08 1.1
Sep 08 2.5

For those who check the daily sunspot number from NOAA, the table was unavailable Thursday evening. As an alternate, the quarterly table is online. The quarterly geomagnetic indices can be found here; you can see that the past few days have been very, very quiet. This is something we probably won't see after the solar cycle picks up, as solar flares and high speed solar wind are more common when the sun is active.

Note the numbers for the first week of November. There are many, many zeroes, which mean less absorption and chance of ionospheric disruption.

There are eight daily K index readings, then one A index for that day. If the K index is zero for the whole day, then the A index is zero. If you saw K of 1 every three hours, then the A index would be 4, K index reading of 2 yields an A index of 7, K equal to 3 means A index of 15. K of 3 and A of 15 are very common during the active portion of the solar cycle. In the table, there are planetary numbers that represent an average of readings from magnetometers in multiple locations, mainly at higher latitudes. The middle-latitude numbers are readings from Fredericksburg, Virginia, and the high latitude numbers are from College, Alaska, at the University of Alaska near Fairbanks.

But perhaps by the time you read this, Friday, November 7 will have a geomagnetic storm. NOAA and the US Air Force predict a planetary A index of 30 for November 7, then 15 the next day, 8 on Sunday and 5 every day until November 25.

On November 4, Australia's IPS Radio and Space Services issued an alert warning of a high speed solar wind from a coronal hole during the period of November 5-8. For November 7, the agency predicts unsettled conditions with isolated active periods; for November 8, mostly unsettled conditions with a chance of isolated active periods are predicted.

Michael Treister, W9NY, of Chicago, says that during the recent CQ Worldwide SSB DX contest (October 25-26) he worked as many countries, zones and stations on 15 meters as he did on 20 meters: "Conditions were amazing." He wrote that on the morning of November 2 he "worked all over Europe with many reports that I was 5/9 plus 20 and 30- just like the good old days. Worked two mobile stations in Greece (they were 5/5-5/7 and q5) and one station in southern England running 10 W to a dipole who was 5/5. He was so excited about the contact that he followed up with an e-mail to me! Most of the stations I worked were running 50 to 100 W and were coming in on my TH7 beam 5/7 or better. This was really good propagation." Michael said that he tried 10 and 12 meters, but got no response. He wrote, "I have not heard signals like this on 15 meters for a couple of years."

Last week Pat Dyer, WA5IYX, of San Antonio, Texas, wrote concerning the CQ Worldwide SSB DX Contest that using a 3 element Yagi at 20 feet he worked 10 meter stations, mostly in Brazil, Uruguay, Argentina and Chile. "This is typical of the band at solar minimum where the F2 path is double-hop without an intermediate ground reflection (oft-called "chordal" or "trapezoidal"). The only things from northern South America noted here were HC8 and OA. There was a conspicuous lack of any Caribbean or Central Americans, though I'm sure that US stations further north (so with longer skip distances) probably had some. They also could have had some Es linking them into the low northern latitudes and then some F2 paths from there."

This bulletin has mentioned the W6ELprop free propagation software from time to time, and Carl Luetzelschwab, K9LA, has a tutorial titled "Downloading and Using W6ELprop" on his personal Web site.

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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