The K7RA Solar Update


A tiny Solar Cycle 24 sunspot group -- numbered 1028 -- emerged briefly on Tuesday, October 20, and then was gone. This is another brief phantom sunspot, teasing us with hints of the expected increase in activity that never seems to manifest. Of course, the silver lining in the low solar activity is low geomagnetic activity. While folks in Alaska miss dramatic aurora, HF hams in the northern latitudes can enjoy the bands without all the disruption that comes with geomagnetic storms.

Sunspot numbers for October 15-21 were 0, 0, 0, 0, 0, 11 and 0 with a mean of 1.6. The 10.7 cm flux was 70.4, 69.6, 70.7, 70.1, 70.9, 71 and 71.3 with a mean of 70.6. The estimated planetary A indices were 4, 4, 2, 1, 1, 1 and 1 with a mean of 2. The estimated mid-latitude A indices were 3, 3, 0, 0, 1, 0 and 1 with a mean of 1.1. Geophysical Institute Prague has a little more detailed forecast for this weekend: They expect quiet conditions for October 23, quiet to unsettled October 24, unsettled on October 25 and back to quiet for October 26-29. Franta Janda, OK1HH, of the Czech Propagation Interest Group expects a bit higher activity, with quiet conditions for October 23 and unsettled to active geomagnetic conditions for October 24-25.

A couple of coronal holes are spewing enough plasma to activate some aurora, but remember that most of the photos you see of beautiful displays in the sky are actually very long exposures taken from a rock-steady tripod mount; many times, the unaided eye cannot perceive the more dramatic details. As a result of solar wind from coronal holes, geomagnetic indices rose yesterday, on Thursday, with planetary A index at 14, mid-latitude A index as measured in Virginia at 12 and the College A index at Fairbanks, Alaska way up to 25.

The College A index has been quiet for a long time; the last time the index was nearly this high was on August 30, 2009 at 24. Prior College A index readings higher than Thursday's were July 22, 2009 at 27, February 4, 2009 at 36, December 6, 2008 at 26 and November 8, 2008 at 30.

Take a look back at daily geomagnetic and solar indices from 1994 to the present. In fact, it is instructive when bemoaning the present lack of solar activity to reflect on times when there was so much geomagnetic activity, that HF propagation was difficult. Notice these 1994 College and Planetary A index numbers and how there were extended periods of heightened activity. In fact, you can see stretches for weeks at a time when there are only spotty records of the College A and K index, and I seem to recall that during these times that their instruments were knocked out of service by energy from geomagnetic storms concentrated in polar regions.

The activity on Thursday was not predicted by USAF and NOAA in their daily 45-day forecast. In the days prior to Thursday (check October 20 and 21), they were still expecting a Planetary A index of 5 for Thursday. Then in the October 22 prediction, they show a Planetary A index of 8 for October 23-25, the weekend of the CQ World Wide SSB DX Contest.

Scott Craig, WA4TTK, has an updated data file for his Solar Data Plotting Utility. This is useful if you are not yet running the program and collecting the data. The data can be updated semi-automatically each week from this bulletin, and manually as well. The new data file has daily solar flux and sunspot numbers from January 1, 1989 through October 7, 2009. This is a good way to visually realize the difference between the previous solar minimum and this extended quiet period we are in.

Brian Webb, KD6NRP, of Ventura County, California, notes that even with no sunspot activity, using low power and a simple antenna, he hears and works many stations overseas on 17 meters. On October 19 at 1556 UTC, he worked PA3HP on PSK on 17 meters after answering his CQ. Brian's antenna was a horizontal delta loop, about 50 feet on each side and fed with 300 ohm twinlead and 100 W. I noted that between his location and the Netherlands on that date, there was a good chance of an opening from 1600-1730 UTC, according to W6ELprop.

Ed Stokes, W1KOK, of Randolph Center, Vermont, asks if there is a W6ELprop version for Macintosh. No, there isn't, although Ed says he would like to port it to Mac. In the November 26, 2008 edition of this bulletin, we answered a similar question, and were pointed toward DX Toolbox, and also a site at for Macintosh ham radio software.

This week, an interesting piece about sluggish flow inside the Sun appeared, authored by two scientists on the GONG project.

Carl Luetzelschwab, K9LA, has another monthly column on propagation in the latest November issue of the now online-only WorldRadio Magazine. It is free, and you can download it in small parts or one big file. Just click on the big "WorldRadio Online" button. Carl's column this month is on short-path summer solstice propagation; it begins on page 22. Also, from that page, you can click a link to see the rules for the CQ World-Wide DX Contest this weekend (Phone) and November 28-29 (CW).

Next week, K7RA will be on the road and it probably won't be practical to get the bulletin to Newington by Friday morning. Instead, we expect to have Steve Nichols, G0KYA, of Wymondham, England, pitching in. Steve is on the Propagation Studies Committee of the Radio Society of Great Britain (RSGB). Steve was the author of the PowerPoint presentation on WSPR he gave at the RSGB convention, which we referenced in last week's bulletin.

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 in The ARRL Letter. 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.