The K7RA Solar Update

SEATTLE, WA, Jun 3, 2005--Both sunspot numbers and solar flux were higher this week, with the average daily sunspot number nearly doubling to 71.3, and average solar flux up by more than 10 points to 93.8. These numbers are compared to the average for the previous reporting week, May 19-25.

Conditions were good at least for most of the first day of last weekend's CQ Worldwide WPX Contest (CW), but Earth passed through a solar wind stream, sparking auroras. By Monday the planetary A index was 67, indicating a strong geomagnetic storm. The effect was not as large as the storm of mid-May, however.

The predicted planetary A index for Friday, June 3, is 15, dropping to 10 for Saturday through Monday, June 4-6. After today predicted solar flux should drop below 95 and possibly stay there until around the end of the month. The Prague Geophysical Institute forecast shows active conditions on June 5-6, unsettled on June 3, 4 and 7, quiet to unsettled on June 8, and quiet on June 9.

Roy Erismann, HB9BJJ, sends news of a new propagation book, Space Weather and Telecommunications, by John M. Goodman. It's very expensive, so I am trying to obtain a copy via interlibrary loan. If anyone has read it, I'd like to hear any reviews.

Larry Lilly, N3CR, of Jim Thorpe, Pennsylvania, (FN20) provided some more 6-meter news. On Thursday, May 26, there was a big opening on 6, and Larry worked stations in Michigan and Wisconsin. The band stayed open until 0230 UTC. Larry runs just 10 W. On May 30 he aimed his 2-element quad to the southeast and worked VP9/N0JK in Bermuda on the first call. Larry's antenna is mounted 20 feet high. He says he's enjoying 6 meters again "after a ten year absence battling 49 MHz baby monitors."

Dave Greer, N4KZ, of Frankfort, Kentucky, reports hearing 6-meter beacons May 28 "from all over North America, but very few live stations." Within a few minutes of each other Dave copied beacons or live stations from W1, C6, Arizona, North Dakota, Florida and Wisconsin. He worked stations in New Mexico, Wyoming and North Dakota.

Eric Christensen, KF4OTN, in Greenville, North Carolina, (FM15) worked VA2LGQ (FN15) in Ottawa, Ontario, on 6 meters on May 26. Eric was mobile running 100 W on 50.125 MHz.

Al Olcott, K7ICW, in Las Vegas, Nevada, reports working several Salt Lake City area stations on 6 meters on May 27, with Utah stations running 10-20 W into vertical whip antennas and coming in very strong. "This is not too unusual where there are dense E clouds," he says. "We were also simultaneously hearing New Mexico stations at 500 miles." Al says several Salt Lake City stations (410-450 miles from him) attempted 2 meter contacts, "but all that was recognized was very weak tropospheric mode. It is typical that 350-450 mile 6-meter paths are accompanied by 2-meter Es openings, but at a distance beyond what is heard on 6, and the same general direction."

Woody Ebersold, KC0THS, of Joplin, Missouri, reports hearing plenty of 6-meter activity on May 29. He says WJ0F in Arizona was so strong, "he dominated 50.135 MHz for over a half hour." A day earlier Woody was on 2-meter FM and, using a vertical, he worked several stations on simplex as far away as Flagstaff, Arizona.

Now that May has turned to June, we can look at some monthly averages in an attempt to discern a trend. The trend overall, of course, is down, but May was actually pretty good with higher sunspot numbers and solar flux compared to recent months.

The average daily sunspot numbers for the months September 2004 through May 2005 were 50, 77.9, 70.5, 34.7, 52, 45.4, 41, 41.5 and 65.4. So, May 2005 had higher average daily sunspot numbers than any month since November.

Average daily solar flux for the same months was 103, 106, 113.7, 95, 102.3, 97.2, 89.9, 85.9 and 99.5. May's average daily solar flux values were higher than any month since January. But this is just one of those bumps on the long slide down Cycle 23, and we are probably still on track to see a sunspot minimum around the end of next year.

A correction. In last week's "Solar Update," we should have reported that Larry Bishop, KB9WLM, worked HK3JRL in Colombia.

For more information concerning radio propagation and an explanation of the numbers used in this bulletin see the ARRL Technical Information Service Propagation page. An archive of past bulletins is available on this Web site.

Sunspot numbers for May 26 through June 1 were 72, 51, 71, 55, 76, 79 and 95, with a mean of 71.3. The 10.7 cm flux was 90.4, 95.5, 92.5, 92.7, 94.9, 96.3 and 94.3, with a mean of 93.8. Estimated planetary A indices were 4, 4, 13, 22, 67, 17 and 8, with a mean of 19.3. Estimated mid-latitude A indices were 1, 1, 9, 16, 32, 10 and 5, with a mean of 10.6.

Amateur solar observer Tad Cook, K7RA, 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. Readers may contact the author via e-mail.

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