ARRL

News

The K7RA Solar Update

09/10/2010

The average daily sunspot numbers for the week rose nearly 13 points to 38.3, while the average daily solar flux was up more than four points at 78.4. On September 2, one new sunspot group emerged, numbered 1105, joining sunspot groups 1101, 1102 and 1103. On September 4, group 1102 faded away, and then 1101 and 1103 vanished on September 6. Group 1105 went over the western side of the Sun by September 9, but a new spot may be emerging in the northeast. On September 9, the sunspot number was 0 and solar flux dropped to 73.7.

Sunspot numbers for September 2-8 were 52, 54, 53, 58, 24, 16 and 11, with a mean of 38.3. The 10.7 cm flux was 77, 77.2, 82.2, 82.1, 79.7, 76.2 and 74.5, with a mean of 78.4. The estimated planetary A indices were 8, 4, 3, 4, 8, 9 and 10, with a mean of 6.6. The estimated mid-latitude A indices were 5, 3, 0, 4, 6, 7 and 8, with a mean of 4.7.

The current prediction from US Air Force and NOAA shows a rising solar flux: 74 on September 10, 75 on September 11-12, 77 on September 13-14 and peaking at 78 on September 15-16. This is lower than the peak of 80 predicted on Wednesday for September 16. After that, a decline in solar flux is expected, then a rise to 80 on October 2-3. Predicted planetary A index is 5 on September 10-11, 10 and 8 on September 12-13, 5 on September 14-18, and 8, 12, 8 on 5 on September 19-22. Geophysical Institute Prague sees quiet conditions September 10-11, unsettled September 12, quiet to unsettled September 13 and back to quiet again on September 14-16.

Looking at the STEREO mission image on early Friday morning, there is a bright area south of the solar equator about to cross the eastern horizon, but we can’t tell yet if this activity will yield any sunspots or not. Currently, about 93.4 percent of the Sun is within view of the STEREO project, and by the end of October, this will increase to about 96 percent.

Chuck Hallett, K4SC, of Mesa, Arizona asked: “What are typical sunspot numbers during the peak of a normal cycle? I see the current values, but have no feel for where that is on a relative scale.”

Current sunspot numbers are quite low, and Solar Cycle 24 is having a long low start that seems to extend longer as time goes by. One way to get an idea of past sunspot numbers and compare them to today is to look at past issues of this bulletin. You can view an archive of past bulletins here.

Here is last week’s bulletin, showing an average daily sunspot number of 25.4, but one year ago, there were zero sunspots! You see how you can just change the year at the end of the URL to get bulletin ARLP035 for every year. Looking at the week’s average sunspot numbers from that bulletin in every year from 1997 to 2010, we see 18.3, 119.3, 90, 135.4, 163.3, 257.1, 122.1, 77.6, 41.1, 21.6, 3.3, 0, 0 and 25.4. You can see we have to go back 13 years to see a level of sunspot activity near where it is now, and there is quite a large range of activity. If you look through the bulletins in 2002, you’ll see some big numbers.

Mark Downing, WM7D has a solar resource page with some historical data. Another tool for visualizing historical sunspot data is here. You can enter any date to see what the sunspot cycle looked like for 11 years around that date. Unfortunately, the links to other sites referenced on this page don’t work.

The Australian government also has a page comparing monthly smoothed sunspot numbers, ranking the fifteen most active months. These are monthly averaged values, which sum all the sunspot numbers for a calendar month, then divides by the number of days. This is a different value than smoothed sunspot numbers, which represent a year of data averaged together.

You can see predicted and past smoothed sunspot numbers on page 11 in the latest issue of the Preliminary Report and Forecast. Note that this table shows the current cycle peaking between February and July of 2013 with a smoothed sunspot number of 90. Back in issue 1701 in April 2008, the prediction was for a cycle peak from August through December 2011, with a smoothed sunspot number of 154; expectations are now much lower.

After viewing images of his beam and tower on a residential lot referenced in last week’s bulletin, a number of readers had questions. How did KD8ID get that big antenna up on that relatively small residential lot, surrounded by neighbors? It seems that this neighborhood has no deed covenants, and KD8ID was able to put up the antenna without a building permit. Before the area was wired for cable television, most people had large outdoor TV antennas on towers, so neighbors were accustomed to seeing antennas. KD8ID reports no RFI complaints from neighbors, perhaps because he has a directional antenna up high. He is also very careful about running high power.

A lot of mail came in concerning the KD8ID antenna and station, pointing out that the average ham couldn’t afford this. But I think it is interesting to hear about stations that some individuals have put a lot of effort into, and for a contester or DXer, his installation isn’t unusual. But it is a matter of degrees. The better the antenna, you will hear the bands open more frequently and the more often you’ll be able to work people.

One e-mail came from John Shannon, K3WWP, of Kittanning, Pennsylvania, indicating that he is having fun with simple wire antennas and QRP. John writes: “Tad, I must both agree with and take somewhat of an exception to KD8ID’s comments in the last propagation bulletin. I definitely agree that propagation is there on all the HF bands most of the time. They sound dead only because no one is transmitting, only listening. That definitely will make them sound dead, even though propagation might be very good at the time. I often call CQ on a ‘dead’ band and wind up with some nice solid rag chew QSOs even with my QRP (or QRPp) and simple wire antennas.

“I think Ron’s statements about antennas can be discouraging to many hams. While it is nice to have super big antennas, this can discourage those who live in apartments, antenna restricted locations and the like from even trying the HF bands. Using simple wire antennas -- such as a random wire in my attic and dipoles in my attic, on my porch or on my roof -- I’ve made at least one QSO using 5 W output or less each day since August 5, 1994 -- or for 5-874 consecutive days. Total QRP QSO’s in that time frame - just under 51,500 of which 13,850+ are DX from 207 entities. Starting with our North American QRP CW Club’s (NAQCC) May Challenge of making as many QRPp (less than 1 W) QSOs as possible during the month, I’ve now made at least one QRPp QSO a day using the above antennas at 930 mW output power. That ‘streak’ is at 126 straight days and counting.

“See my Web site to get even more info on what can be done with a very minimal QRP setup. Oh, the key (pun intended) is to use the best and most efficient of all ham radio modes -- CW. All my QSOs are CW only. Please don’t discourage your readers by emphasizing the use of big antenna systems for making QSOs. Big antennas help, but they are definitely not a necessity, especially if you use CW.”

Thanks, John. I don’t think there is anything wrong with talking or writing about big antennas, wire antennas in your attic -- or any antenna. It’s all part of the big wide world of ham radio, and even if I don’t have enough room or money for a truly big antenna, I still enjoy hearing about them.

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.



Back