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The K7RA Solar Update

07/24/2009

No new sunspots yet, but a big surprise this week with aurora and a geomagnetic storm: Sunspot activity peaked around 0300-0900 UTC on Wednesday July 22, with K index as high as 6. The planetary A index for the day was 24. You can see the K index variation here. One nice result was aurora propagation on 6 meters. A week ago there wasn't any indicator of increased activity. If you go here and click on July 21, you can see that the forecast was modified more than once, but the highest forecast was an A index of only 15. There is a new sunspot trying to emerge today (July 24), but it looks to be from Solar Cycle 23.

Sunspot numbers for July 16-22 were 0, 0, 0, 0, 0, 0 and 0 with a mean of 0. The 10.7 cm flux was 66.7, 66.2, 67, 67.6, 68.2, 67.7 and 67.8 with a mean of 67.3. The estimated planetary A indices were 4, 2, 3, 2, 6, 4 and 24 with a mean of 6.4. The estimated mid-latitude A indices were 2, 0, 1, 1, 3, 3 and 18 with a mean of 4. Geophysical Institute Prague predicts quiet geomagnetic conditions July 24-25, quiet to unsettled July 26 and back to quiet for July 27-30. The US Air Force and NOAA Space Weather Prediction Center calls for planetary A index of 5 for July 24-25, 8 on July 26, 7 on July 27 and back to 5 though the end of the month. They predict solar flux on July 24-26 at 68, 69 and 70, remaining at 70 through August 7.

KN5O and N5OMG in Louisiana both worked JA7QVI on 6 meters on June 17. KN5O worked him at 2359 UTC, and 30 minutes later reported that the JA7QVI signal was still holding steady at S2. This was on a Friday, five days before the aurora.

Patrick Hamel, W5THT, in Mississippi on July 17 noted that July propagation on 6 meters is some of the best he has ever experienced. He wonders if the volcano erupting on Sarychev Peak on Matua Island is spewing conductive ash, possibly reflecting radio waves. I don't know if that is true or not, but you can see dramatic photos of the eruption.

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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