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ARRL Propagation Bulletin ARLP023 (2005)

ARLP023 Propagation de K7RA

QST de W1AW  
Propagation Forecast Bulletin 23  ARLP023
From Tad Cook, K7RA
Seattle, WA  June 3, 2005
To all radio amateurs 

ARLP023 Propagation de K7RA

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 over 10 points to 93.8. These numbers are compared to
the average for the previous reporting week, which was May 19-25.
This week's numbers are in the last paragraph of this bulletin.

Conditions were good for last weekend's CQ World-Wide WPX CW
Contest, at least for most of the first day. But earth passed
through a solar wind stream, sparking auroras, and by Monday the
planetary A index was 67, indicating a strong geomagnetic storm.
But the effect was not as large as the storm during mid-May.

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

Roy Erismann, HB9BJJ sent news of a new book on propagation. It is
titled "Space Weather and Telecommunications," by John M. Goodman.
The book is very expensive, so I am trying to get it locally via
interlibrary loan. If anyone has read it and would like to comment,
I'd like to hear any reviews.

Larry Lilly, N3CR of Jim Thorpe, Pennsylvania (grid FN20) wrote in
with 6-meter news. Thursday, May 26 there was a big opening on
6-meters, and Larry found openings in both the morning and the
evening, with stronger signals in the later period. He worked
stations in Michigan and Wisconsin, and the band stayed open until
10:30 PM EDT (0230z). Larry runs low power, and with 10 watts on May
30 he aimed his 2 element quad to southeast and worked VP9/N0JK in
Bermuda on the first call. Larry's antenna is mounted 20 feet high.
Larry is enjoying 6-meters, getting on "after a 10-year absence
battling 49 MHz baby monitors."

Dave Greer, N4KZ of Frankfort, Kentucky was hearing 6-meter beacons
last Saturday (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 on 6-meters 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 using 100 watts on 50.125 MHz USB.

Al Olcott, K7ICW in Las Vegas on May 27 worked several Salt Lake
City area stations on 6-meters, with Utah stations running 10-20
watts into vertical whip antennas and coming in very strong. He
wrote, "This is not too unusual where there are dense E clouds. We
were also simultaneously hearing New Mexico stations at 500 miles."

Al also says that several Salt Lake stations (410-450 miles from
him) attempted 2-meter contacts, "but all that was recognized was
very weak tropospheric mode." He also wrote, "It is typical that
350-450 mile 6M paths are accompanied by 2M Es openings, but at a
distance beyond what is heard on 6M, and the same general

Woody Ebersold, KC0THS of Joplin, Missouri heard plenty of 6-meter
activity on May 29 and said WJ0F in Arizona was so strong, "he
dominated 50.135 MHz for over a half hour." The day before, May 28,
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.

The report in last week's bulletin about Larry Bishop, KB9WLM on
6-meters should have read "he worked Columbian station HK3JRL at
2320z on 50.135 MHz." This generated a ton of mail, because as
everyone pointed out, HK is for Colombia, not South Korea (HL), and
it was HK3JRL, not an HK2 call.

If you would like to comment or have a tip, email the author at,

For more information concerning radio propagation and an explanation
of the numbers used in this bulletin see the ARRL Technical
Information Service propagation page at, An archive of past
bulletins is found at,

Sunspot numbers for May 26 through June 1 were 72, 51, 71, 55, 76,
79 and 95 with a mean of 71.3. 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.


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