Propagation de K7RA

21 July, 2007

This week saw an increase in average daily sunspot numbers, rising over 8 points to 29.3. Expect to see a lower average for next week, with perhaps some zero-sunspot days. Perhaps early August will have sunspot numbers back in the twenties at least. Currently sunspot 963 is disappearing from view.

Right now there is a solar wind stream headed toward our planet. This should only be a minor upset, with planetary A index around 15 for today and tomorrow, July 20-21. Currently the IMF (interplanetary magnetic field) points south, which makes us vulnerable.

Geophysical Institute Prague predicts unsettled to active conditions for July 20, unsettled July 21, quiet to unsettled July 22, quiet for July 23-25, and unsettled July 26.

Check out the July 2007 issue of Sky and Telescope, for an article titled ''Solar Forecast: Storm Ahead''. Thanks to K9LA, EI4HQ, and AI4VV for the tip, and to N7SO for mailing a copy. The article discusses predictions for the next solar cycle, different methods for predicting it, and the hazards for space travel and communications from solar events.

Scott Avery, WA6LIE of Salinas, California (CM96) reports fantastic conditions on six and two meters last weekend. On July 14 from 1600-2100z six meters sounded like 20 meters on a good day, and he could work all over the East Coast, ''Maryland, Carolinas, Florida and everything between.'' At one point he heard a Colorado station declare that E-skip was coming in on 2 meters, so he swung his 13-element Yagi toward the east. He heard K0GU, N0VSB and KC0COU with signals above S9. He also worked out of state when he switched from 45 watts and the Yagi to 5 watts and a vertical. Several other stations in CM96 with low power and simple 2-meter antennas also had good results.

Steve Miller, N0SM of Ottumwa, Iowa (EN30) has a response to the recent comments from K0MHP about six meters, magic band or invisible band. He writes, ''There have been openings if one can catch them but part of it is living in the proverbial Black Hole of the Midwest. We occasionally get stations from the Caribbean and on rare occasions some European stations. The really successful Midwest ops on 6 have to study propagation patterns very carefully and even then a big dose of good luck goes with it. An excellent radio and antenna system are also vital. But in general, many of us share his
frustrations.''

William Henry, W8QP of Morgantown, West Virginia asked about graphs of sunspots covering several centuries, back to the first recorded sunspot counts. You can find them at
http://wm7d.net/hamradio/solar/historical.shtml.

Stan Horzepa, WA1LOU wrote recently in his Surfin' feature on the ARRL web site about Long Delayed Echoes. You can find the LDE stories listed under L in this index, at
http://horzepa.com/blog/?page_id=116. In the latest piece, he mentions one of those baffling, ''unexplainable'' stories about a television signal received several years after the original transmission, which is a tale that I heard as a child. In this case, the ''ghost'' transmission was from a station off the air for several years, with the signal supposedly wafting around the universe at a velocity much slower than the speed of light.

Often this kind of thing, like many UFO stories, becomes much less mysterious yet more interesting if you can find additional facts, and perhaps another perspective. I offer two of those, here: http://www.snopes.com/radiotv/tv/klee.asp and here: http://www.bvws.org.uk/405alive/history/
eyes_of_texas.html .

In last week's bulletin ARLP029, the dates for the numbers at the very end were misstated as June instead of July. Just changing the word June to July will get you on the right track. But if you use WA4TTK's Solar Data Plotting Utility, which can grab the data out of a text file, not only did you not get the numbers for the week, but the nifty automatic updater has messed up your data file. To correct this, you can make the change to last week's bulletin, then grab the data using the Utility, then to correct the bad data from June, update numbers from ARLP024 and ARLP025. A source for past bulletins is at the end of this bulletin.

However, you can avoid that trouble by downloading a new corrected graph.dat file from the WA4TTK web site, which will give you all of the sunspot and solar flux data from the start of 1989 through the eleventh of this month.
The software and the data file are free at http://www.craigcentral.com/sol.asp. The data file is also useful with a spreadsheet program, and you can use the free plotting software to automatically update the data weekly.

If you would like to make a comment or have a tip for our readers, email the author at, k7ra@arrl.net.

For more information concerning radio propagation, see the ARRL Technical Information Service at
http://www.arrl.org/tis/info/propagation.html.

For a detailed explanation of the numbers used in this bulletin, see http://www.arrl.org/tis/info/k9la-prop.html.

An archive of past propagation bulletins is at http://www.arrl.org/w1aw/prop/ . Monthly propagation charts between four USA regions and twelve overseas locations are at http://www.arrl.org/qst/propcharts/.

Sunspot numbers for July 12 through 18 were 25, 38, 41, 41, 30, 17 and 13 with a mean of 29.3. 10.7 cm flux was 76.9, 78, 75.7, 74.7, 72.9, 72.3, and 69.6, with a mean of 74.3. Estimated planetary A indices were 8, 4, 23, 13, 6, 5 and 3 with a mean of 8.9. Estimated mid-latitude A indices were 6, 5, 12, 11, 4, 2 and 3, with a mean of 6.1.

Source: The American Radio Relay League

• All propagation reports can be found at:
http://www.southgatearc.org/propagation