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The K7RA Solar Update


The average sunspot numbers for the week were up nearly 44 points to 55.6, while the average solar flux readings remained unchanged, at 84.9. For a few days, solar flux values rose above 90, but currently the projection from USAF and NOAA for solar flux over October 22-31 is 82, 82, 82, 82, 80, 80, 80, 80, 80 and 80. The same forecast predicts planetary A index for the same period at 5, 10, 15, 12, 5, 5, 5, 5, 7 and 7. Geophysical Institute Prague predicts quiet conditions on October 22, quiet to unsettled October 23, unsettled October 24-25 and quiet October 26-28.

Seven new sunspot groups arrived this month: group 1112 appeared October 9; group 1113 on October 13; groups 1114 and 1115 on October 14; group 1116 on October 17, and groups 1117 and 1118 on October 19. While the average sunspot number for the past week was 55.6, the greatest sunspot activity was over the past few days with the daily sunspot numbers on October 17-20 at 61, 69, 65 and 61. Sunspot numbers for October 14-20 were 34, 51, 48, 61, 69, 65 and 61, with a mean of 55.6. The 10.7 cm flux was 80.4, 82.2, 86.9, 83.6, 90.6, 86.6 and 83.9, with a mean of 84.9. The estimated planetary A indices were 2, 5, 6, 11, 5, 5 and 4, with a mean of 5.4. The estimated mid-latitude A indices were 0, 3, 3, 10, 3, 7 and 3, with a mean of 4.1.

Check the new November issue of WorldRadio Online for two articles of interest concerning propagation. The first is a piece beginning on page 14 about gray line propagation, and on page 38 is Carl Luetzelschwab’s, K9LA, excellent monthly Propagation column. This month, Carl addresses questions that arose when news articles appeared describing a shrinking thermosphere. Did this affect propagation? Carl’s data shows that it probably did not.

Last week’s bulletin mentioned the WSPR program and the article about it on page 30 in the November 2010 issue of QST. A useful tool generated by this network is the map. You can look at weak-signal propagation over all bands for the past 24 hours, or look at any of the dozen individual amateur bands from 2 to 160 meters, plus VLF. You can limit your view down to 30 minutes, 1 hour, 3 hours, 6 hours, 12 hours or 24 hours. WSPR is not a mode where you can converse with other stations, but rather an automated network that picks up weak signals from other stations in the network and displays the propagation paths. Because it is effective with such weak signals, it isn’t clear how this might be used to indicate a possible path for an SSB QSO, for example.

Jim Muiter, N6TR, of San Mateo, California, said that on Thursday morning, he picked up the 10 meter NCDXF beacon in South Africa, ZS6DN, around 1700 and it disappeared a few hours later. In the past, this has been an indicator of improving conditions. Northern California DX Foundation operates beacons worldwide on 10, 12, 15, 17 and 20 meters. These are very useful for determining when the bands are open.

In response to W7EET’s query in last week’s bulletin, Dave Parslow, VK3AIF, of Melton, Victoria, Australia (about 25 miles WNW of Melbourne), wrote to tell us about a Web site that the Australian government operates that uses real time ionosonde (ionospheric sounder) data to predict propagation. Unfortunately, we don’t have a system like that here, but it can be used to predict propagation from North America back to the South Pacific.

Dave wrote: “I don't know if you have a similar service available in North America, perhaps I should research that before putting pen to paper so to speak, but what I use here is the Hourly Hap Charts published by the Australian Government Ionospheric Prediction Service (IPS). The IPS posts these charts hourly using near-real time data gathered from ionograms, a list of their locations is also available on the above site and overlay a map with colored contours representing different frequencies in the HF spectrum. They can be read at a glance and the optimal frequency determined for your particular path of interest. I go here in my java-enabled browser and select my approximate location from the drop down list and the map appears centered on my preferred position. There are many other useful tools on the site, with many having the amateur bands selectable from the options.”

Thanks, Dave!

Stan Gubiotti, VE7IEF, of Abbotsford, British Columbia, asked what I think is happening with Solar Cycle 24 and when the peak might occur. I think Solar Cycle 24 is weak! Regarding the peak, I will refer to the NOAA space weather Preliminary Report and Forecast. The latest issue with a cycle forecast is PRF-1831 from October 5. On page 10, we see a table showing the smoothed sunspot number predicted to peak at just 90 between February and July in 2013. Unfortunately, this table doesn’t have the months labeled across the top, but I can assure you that the left hand column is always January, and the right hand column is December.

Stan also asked about the meaning of various terms used in this bulletin, and for this question I refer him to the links toward the bottom of this bulletin.

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 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 at




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