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The K7RA Solar Update


This past week, there was a decline in the solar and geomagnetic indices: The average daily sunspot number dropped nearly 21 points to 57.7, while the average daily solar flux softened by 4.7 points to 100.9 and the average daily planetary A index declined 6.4 points to 5.1. This isn’t much of a change, but geomagnetic activity was low already, and this is even lower.

Sunspot numbers for February 21-27 were 75, 79, 56, 25, 59, 49 and 61, with a mean of 57.7. The 10.7 centimeter flux was 108.5, 107, 99.6, 94.9, 95.4, 98.7 and 102, with a mean of 100.9. The estimated planetary A indices were 6, 9, 6, 3, 3, 5 and 4, with a mean of 5.1. The estimated mid-latitude A indices were 5, 9, 6, 2, 3, 4 and 4, with a mean of 4.7.

The predicted solar flux for the near term is 110 on March 1-3, 105 on March 4-7, 100 on March 8, 95 on March 9-14, 100 on March 15-16, 105 on March 17, and rising to 110 on March 18-20. The solar flux then reaches a peak of 120 on March 25-27, and on March 28-April 6, it looks like it will hover around 113. The predicted planetary A index is 12 and 8 March 1-2, 5 on March 3-4, 8 on March 5, 7 on March 6-7, 5 on March 8-10, 7 on March 11-12, and back down to 5 on March 13-20.

This weekend is the ARRL International Phone DX Contest, which runs from 0000 UTC March 2 to 2359 UTC March 3.

Now that February is over, let’s look at some updated averages. Our most recent three-month moving average -- centered on January 2013 -- is not impressive with its average daily sunspot number of 73.6. This is below every three-month moving average for last year, except the three months centered on March 2012, which was 71.2. The three-month moving averages of daily sunspot numbers centered on January 2012-January 2013 were 83.3, 73.7, 71.2, 87.3, 91.5, 96.5, 91.9, 89.9, 81.2, 82.3, 74.4, 82.8 and 73.6.

Jim Henderson, KF7E, of Queen Creek, Arizona, sent a link to an impressive NASA video of solar activity from last July. Note that you can set this video to HD resolution, and it looks great on full screen. You might also want to check out this photo gallery of solar events. Note the dramatic composite image number 4.

Walt Knodle, W7VS, of Bend, Oregon, sent an article about artificial ionosphere with a 3.6 MW signal on 69 meters produced by the High Frequency Active Auroral Research Program (HAARP) facility in Alaska. Note that they are only able to produce the effect for 45 seconds.

Jim Smith, K3RTU, of Aston, Pennsylvania, operated on HF CW from Ridley Creek State Park in Southeast Pennsylvania (grid square FM29) on February 25. He wrote: “I hooked up with Bal, EA8BVP, in the Canary Islands. This CW contact took place early in the afternoon on 18.086 MHz. I had been trying to make a contact on 20 meters and was having no luck so I switched over to 17 meters and almost within minutes, I heard EA8BVP calling CQ. Both of our signal levels were S4 to S5. I frequently operate on 17 meter CW while out backpacking and more often than not, it provides me with good long distance contacts.”

It looks like the path from the park to Canary Islands would be good in the early afternoon, with the best 17 meter signals that day from 1200-2200. Seventeen meters does look like a better bet, with 20 meters not catching up until after 2000.

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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