Propagation de K7RA

In the past few days sunspots have reappeared after six days of nothing. In April so far we've seen 18 days with 0 spots. But currently a large sunspot, number 953 is rolling into view. A solar wind stream is also expected to hit earth, causing geomagnetic upset on Saturday, April 28.

The Australian Space Forecast Centre predicts quiet to unsettled conditions on April 27, active to minor storm on Saturday, April 28, and active conditions on April 29. The U.S. Air Force predicts planetary A index from April 27 through May 1 at 5, 25, 15, 10 and 8. Similar predictions from Geophysical Institute Prague give us quiet conditions for April 27, active on April 28, unsettled to active April 29, unsettled April 30, quiet to unsettled on May 1, and back to quiet on May 2-3.

Lots of news this week on the solar minimum and predicted solar maximum. On April 25, a Solar Cycle 24 Prediction Panel, consisting of members from NOAA, NASA and other agencies looked at all available predictions and attempted to reach a consensus. It looks like the minimum between cycles 23 and 24 may not occur for another year, until March 2008, a year later than recently reported. The accuracy is expected to be plus or minus six months. The peak of cycle 24 is expected to occur in October 2011 if there is a large solar cycle, and August 2012 for a small cycle. You can see their
statement at, http://www.sec.noaa.gov/SolarCycle/SC24/
Statement_01.html.

Many people sent links to articles about this. Frank Donovan, W3LPL of Glenwood, Maryland sent a couple of links, including one with a graphic representation of a range of predictions at, http://www.sec.noaa.gov/SolarCycle/
SC24/ssn_predict.gif. Also check http://www.sec.noaa.gov/
SolarCycle/SC24/ for other info, including PowerPoint presentations. If you don't have PowerPoint, you can find a free PowerPoint viewer to download for Mac or Windows by
searching for the two words PowerPoint Viewer in Google, or any other search engine.

An AP story is at, http://seattlepi.nwsource.com/national/
313152_solar26.html, and on the web at,
http://www.space.com/scienceastronomy/
060818_sun_cycle.html link.

We received a large volume of mail this week, and hope to get to more of it in the next bulletin. Among reports was some unusual 6 meter backscatter propagation observed by Bill Van Alstyne, W5WVO of Rio Rancho, New Mexico on April 21.

I'll let Bill describe it: "Greetings from New Mexico, DM65. Just finished a very unusual opening off of a pre-season Es cloud in northern Mexico, approximately 2315-0100z. Many central Mexican stations in XE1/XE2 with 59++ sigs, but the real news was the amazing strength of the backscatter signals coming in from Arizona, New Mexico, Utah, Texas, and California, all peaking with the beam pointed due south. Was able to work a couple of new close-in grids in AZ, as well as many other grids I already had. Strongest
backscatter signals were from Bob, W7UT, in southwest Utah; Bud, N7CW, in Prescott, AZ; and Tommy, W7RV, in Scottsdale, AZ. All were consistently 56/57 until the propagation began to weaken around 0030z."

Bill continues, "This is by far the strongest backscatter I've ever heard on 6M. As a rule, Es clouds (due to their very thin, flat architecture) are very poor backscatter producers; the only previous backscatter I've ever worked off of 6M Es was extremely weak. This backscatter propagation was ragchew quality, and lasted virtually without QSB for over an hour."

Also this week we saw some of the early 3-D images from the NASA STEREO satellites. To view in 3-D, you need those paper glasses with a red filter covering the left eye, and cyan filter over the right eye. You can see the images at,
http://www.nasa.gov/mission_pages/stereo/
news/stereo3D_press.html.
They also have info on where to find the glasses. I found mine for well under a dollar at Science, Art and More, a shop that sells products for science education in my neighborhood.

I must admit I was a little disappointed, but only a little. At the distance these solar images are taken, the depth effect of the sun shows it as very close to a perfect sphere, in my estimation. Perhaps I was hoping for detailed looks at the surface with exaggerated three-dimensional effects that would enhance the perception of depth and detail. But I have no doubt that the images shown on that page are probably accurate, more so than what I had imagined.

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 April 19 through 25 were 0, 0, 0, 0, 0, 0 and 14 with a mean of 2. 10.7 cm flux was 68.3, 68.5 68.7, 68.9, 69.1, 73.2, and 76.5, with a mean of 70.5. Estimated planetary A indices were 6, 3, 2, 10, 18, 4 and 5 with a mean of 6.9. Estimated mid-latitude A indices were 4, 2, 2, 8, 10, 5 and 4, with a mean of 5.

Source: The American Radio Relay League

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