Register Account

Login Help


The K7RA Solar Update


The average daily sunspot numbers were up 2.5 points from last week, despite the fact that there were no sunspots at all this week on June 15-16. A new sunspot group 1082 emerged yesterday, June 17, and yielded a daily sunspot number of 14. A nice thing about this spot is that it is all the way over on the east side of the visible solar disk, meaning we will probably see its effects as it moves across the Sun. All other recent sunspots emerged toward the west side, meaning that they went over the horizon fairly quickly and disappeared. Sunspot numbers for June 10-16 were 41, 43, 46, 46, 12, 0 and 0, with a mean of 26.9. The 10.7 cm flux was 72.9, 74.6, 76.2, 76.3, 72.8, 70.1 and 71.6, with a mean of 73.5. The estimated planetary A indices were 6, 5, 3, 6, 5, 10 and 19, with a mean of 7.7. The estimated mid-latitude A indices were 5, 4, 1, 5, 3, 9 and 13, with a mean of 5.7.

Last week, there were four sunspot groups visible at different times: Group 1078 disappeared on June 12; 1079 and 1080 both were gone on June 14, and on June 15, 1081 was gone.

Geomagnetic activity peaked on June 16 with the planetary A index at 19 and high latitude College A index at 42. This should decline over the next couple of days. We did not receive a prediction from Geophysical Institute Prague this week, but NOAA/USAF say that the expected planetary A index for June 18-28 is 10, 5, 5, 5, 5, 5, 8, 12, 15, 15 and 8. This shows unsettled to active geomagnetic conditions for Field Day weekend, June 26-27. The same prediction shows solar flux at 70 on June 18-24, then 75 for June 25-30.

Glen Stuart, N7NRA, of Mesa, Arizona sent this in about recent 10 meter activity: “Dave Jones, N7YU, in Chandler, Arizona, and I had QSOs into Rarotonga at 0045 on June 14 on 28.445 MHz. The op on the other end was Jim Ditchburn, E51JD. Signals were fading in and out, but we were reporting 57 on both ends. I don’t know how much power Dave was running. I was using 100 W. We both use Butternut HF-9Vs. His is ground mounted, mine is roof mounted with the base at about 15 feet above ground. When I built my shop, I had the roofers install a carpet of chicken wire between the shingles and the tar paper. My counterpoise is about 16×50 feet and works well. Things are looking up for the higher frequencies.”

On that same date, June 14, the K0KP 6 meter beacon was copied in the Netherlands. Rex Greenwell, K0KP, lives in Duluth and operates a 100 W beacon on 50.073 MHz at the 50 foot level on a commercial broadcast tower in grid square EN36wt. Here is the message from Rex. “This is an e-mail I received from PF7M today from the Netherlands. This was at 1:50 AM Central Daylight Time -- 6 meters, Europe to Minnesota in the wee hours of the AM!

‘Hello Rex, This morning round 0650 UTC I have received your K0KP/B beacon on 50.073MHZ. Just audible at 419 with my 6 element Yagi at 20 meters. Locator here: JO33BA. Six meters was open from here to GM and OY, so think it was some extended Es into EN36. Not any NA present on 6 meters at this time. 73, Johan, PF7M.’”

Several readers sent in links to articles on our Sun’s recent strange behavior, including this one and this one on the NASA Solar Observatory.

In last week’s bulletin, we raised the question about adjusted solar flux values and why they are adjusted to compensate for the variation in the distance between Earth and Sun. The solar flux values we present here are the values as measured at the observatory in Penticton, British Columbia. You can see them here. They come from the 2000 reading in the third column from right, with the heading “fluxobsflux.” The next column to the right, “fluxadjflux,” is the adjusted value. They are adjusted up or down to reflect a value based on the average distance of our planet from our Sun.

On June 17, 2010 at 2000, the raw observed value was 70.4 and the adjusted value was 72.7. This is because we are now further away from the Sun than other times of the year. Of course, we are interested in the observed value, because that is a measure of the radiation hitting our ionosphere. But if we wanted to keep track of adjusted solar flux to gauge solar activity, this would show us more realistically what the sun is actually doing. Back on April 5, the observed and adjusted readings show the same value, but in January, we were closer to the Sun, so the value was adjusted downward.

This weekend is the All Asia CW DX Contest, and HF conditions should be fair. There are no predicted geomagnetic disturbances.

The new issue of WorldRadio online should be out this Sunday, June 20, and there is always an informative column on propagation by Carl Luetzelschwab, K9LA

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




Instragram     Facebook     Twitter     YouTube     LinkedIn