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The K7RA Solar Update


Both the average daily sunspot numbers and the solar flux were up this week, with the sunspot numbers rising nearly 57 points to 138.1, and the average daily solar flux up more than 25 points to 138.8. Paired with the average daily planetary A index dropping from 9.4 to 4.1, this is great news for HF propagation. On April 8, the daily sunspot number reached 162; two days later, it was at 163. This is the highest level since January 11 when it was 166. On Thursday, April 11, an Earth-directed coronal mass ejection (CME) erupted on the Sun. It is expected to arrive on Saturday, April 13.

Sunspot numbers for April 4-10 were 119, 146, 117, 144, 162, 116 and 163, with a mean of 138.1. The 10.7 centimeter flux was 128.5, 134.4, 137, 137.8, 139.2, 146.5 and 148, with a mean of 138.8. The estimated planetary A indices were 4, 3, 5, 5, 3, 4 and 5, with a mean of 4.1. The estimated mid-latitude A indices were 3, 3, 4, 5, 4, 4 and 5, with a mean of 4.

The latest solar flux prediction from the US Air Force and NOAA sees flux values of 138, 135, and 130 on April 12-14, 125 on April 15-16, 120 on April 17, 115 on April 18-19, 95 on April 20-23, then 100, 105, 110, 115 and 120 on April 24-28, 120 on April 29-May1, then rising to a peak of 138 on May 5. The predicted planetary A index is 5 on April 12, 26 on April 13, 45 on April 14, 8 on April 15, 5 on April 16-22, then 12, 8, 18 and 15 on April 23-26, 5 on April 27-May 4, and rising to 8 on May 5.

A predicted A index of 45 is a big number. On April 11 at 2358, I received a geomagnetic disturbance warning from the Australian government’s Ionospheric Prediction Service: “A full halo earthward directed CME was observed on April 11 with estimated arrival late on April 13. Geomagnetic activity is expected to rise up to major storm levels due to the effect of this CME late on April 13 and through most parts of the day April 14.” They predict quiet to major storm on April 13, then major storm down to unsettled conditions on April 14.

Jon Jones, N0JK, of Lawrence, Kansas, followed up on his comments in last week’s bulletin about propagation in the Pacific: “The distance between Hawaii and Wake Island is around 3925 kilometers -- close to the limit of a standard F2 hop, which is about 4000 kilometers -- thus, an optimum F2 path for the lowest possible MUF. Possibly the F2 is off the northern high MUF ridge. Hawaii and Wake Island are both about 20 degrees geomagnetic north. The 6 meter path between Hawaii and Wake Island appears to be reliable and consistent. KH7Y heard the KH9/WA2YUN/b this morning (April 5) from 0500 to after 0720 UTC. The beacon runs 50 W to a loop antenna.”

Bruce Smith, AC4G, of Taft, Tennessee (grid EM65) reports: “I was so excited to contact VK9CZ on 80 meter CW that I had to write in. Our QSO took place on April 3 around 2345 when both VK9CZ and I were in sunlight at the edge of the terminator. This had to be one of my best QSOs ever due to the level of difficulty, the distance and no darkness at either location (so my terminator map showed). The VK9CZ signal was S5-S7 on my transmit antenna (vertical). The signal was so strong that my separate receive antenna was not required. Since that date, I have not been able to copy their 80 meter signal. I guess it was one of my luckiest days to be able to make this QSO.”

Sounds like fun! At that day and time, I would expect good propagation on both 15 and 17 meters, VK9CZ is the Cocos-Keeling DXpedition, and the path was exactly 10,843 miles, or 17,450 kilometers. Time given of 2345 UTC was four minutes after sunrise at the South Pacific end, and 21 minutes prior to sunset on the Tennessee end.

Robert Elek, W3HKK, of Johnstown, Ohio, sent this account of his participation in a club effort for the CQ World Wide WPX SSB Contest from two weeks ago: “WW8OH and the Cooken ARC Contest Animals had been planning for months to give the WPX contest a shot. The week didn’t look promising, with the smoothed sunspot numbers dropping and the A indices in the 20s. Add to that the warm weather with its high static on Friday night, the odds were stacked against us. The DX wasn’t that good; 10 was spotty, 15 was better but not great and 20 and40 meters were loaded with signals, but nowhere to go.

“WW8OH -- with 400 W to a 35 foot high hex beam and a 70 foot high, 600 foot horizontal loop -- has been on a quest to score 1000 contacts and 1 million points in some contest! Any contest! So far this year, we’d get 600 contacts on Day One, but we would struggle on Day Two, always falling short, with QSO totals usually in the mid-800s. We were thinking that WPX could do it for us, thanks to domestic and DX contacts being allowed.

“Friday was a steady slog, all night. Heavy static hurt scores on the low bands. Saturday was more of the same, but the static was easing. Around 9 PM on Saturday, we moved to 40 meters and began to work stations: one at a time, then two, then three, then a small pile, then stations 10 deep! We were logging them as fast as we could. Our rates were building, finally peaking out at 149 contacts per hour, per the 20 minute adjusted number. We were having a ball! This went on for five hours, until around 2 AM on Sunday. There were loud ones, weak ones, in-between ones. We heard mostly stateside signals. Bless the West Coast -- they were all on the air in droves. By the time we broke for sleep around 3 AM, we had already set club records with 1100 contacts and 1 million points. What an amazing run on 40 meters; nearly half of our contacts had come on 40 meters!

“We resumed around 11 AM on Sunday, focusing on 10, 15 and 20 meters, but we couldn’t build up a run. By 6 PM, we were up to 1300 contacts, but our (new) dream of hitting 1500 was dying. At 7 PM, we decided to see if 40 meters had another run left in it. First it was quiet, and it began again: A few contacts, then more, then another pileup! We spent the last 55 minutes in ham heaven, with rates at more than 100 an hour, until we heard a carrier at 7:55, followed by music. A broadcast station ended it for us, and we finished with 1449 contacts and a claimed score of more than 1.5 million points.

“It feels good to hear the pileup calling you! We worked a lot of DX, Antarctica, Australia, New Zealand, Japan, the Philippines, Indonesia, Morocco and a fair number from the northeast coast of Brazil. I remember working some of these hams back in the 1960s; they’re still going at it, still getting a thrill out of contesting. There is hope for all of us! So even when propagation is far from optimum on 10, 15 or 20 meters, don’t sell 40 or 80 short. On this weekend, 40 meters was in amazing shape for domestic contacts.”

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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