The K7RA Solar Update


Today's bulletin is going out on Monday instead of Friday, due to last week's Thanksgiving holiday. The last Solar Update was released on Wednesday, November 26. Starting Friday, December 5, we return to a regular Friday weekly bulletin schedule.

Currently, there are no sunspots visible, and solar flux hangs around 68. The predicted solar flux is expected to rise to 70 December 8-9. Perhaps then we will see the return of a region that spawned sunspots during the last solar rotation. Geomagnetic indices have been quiet, but they are also expected to rise this Friday, December 5; the Planetary A index for that day is predicted to be 15. The average sunspot number for November was 6.8, up from 5.2 for October. The three month sunspot number average ending November 30 -- centered on October -- was 4.5. This was an increase from August and September's 1.1 and 2.5.

Sunspot numbers for November 20-26 were 0, 0, 0, 0, 0, 0 and 0 with a mean of 0. The 10.7 cm flux was 69.6, 68.5, 69, 69, 67.9, 67.7 and 68.3 with a mean of 68.6. The estimated planetary A indices were 2, 1, 1, 3, 0, 10 and 8 with a mean of 3.6. The estimated mid-latitude A indices were 1, 0, 0, 1, 2, 11 and 11 with a mean of 3.7.

Here are the 3-month averages of sunspot numbers since mid-2006:
Jun 06 28.9
Jul 06 23.3
Aug 06 23.5
Sep 06 21.2
Oct 06 24.1
Nov 06 23.1
Dec 06 27.3
Jan 07 22.7
Feb 07 18.5
Mar 07 11.2
Apr 07 12.2
May 07 15.8
Jun 07 18.7
Jul 07 15.4
Aug 07 10.2
Sep 07 5.4
Oct 07 3.0
Nov 07 6.9
Dec 07 8.1
Jan 08 8.5
Feb 08 8.4
Mar 08 8.4
Apr 08 8.9
May 08 5.0
Jun 08 3.7
Jul 08 2.0
Aug 08 1.1
Sep 08 2.5
|Oct 08 4.5

It looks like we had a double minimum, ten months apart.

If you check the thrice-daily solar flux readings from the Dominion Radio Astrophysical Observatory (DRAO) near Penticton, British Columbia, I found the data ending November 20 -- the updated data is now here. If you go here, you can access a table of monthly solar flux averages back through February 1947. The number you want is the Observed Flux in the first column.

Over a week ago Randy Crews, W7TJ, of Spokane, Washington, wrote, "Reviewing my old logs and operating activity, the frustration many of us HF aficionados feel is due to the extended period between the end of Solar Cycle 23 and the beginning of Solar Cycle 24. I have been on the air 44 years and never have I seen a cycle with such a long extended bottom. Usually the bottom is brief -- maybe 6-9 months of low sunspot numbers and solar flux values in the mid-60s. The rise and fall is and has historically been short. Looking back (depending on where one measures), there is a very long and stretched bottom spanning 1.5 to 2 years. Graphically instead of a 'V,' we have a 'U' with a long flat bottom. It would be nice to have a payback similar to Solar Cycle 19 for the dues we have all paid." Randy refers to Solar Cycle 19 -- the "big one" that peaked in the late 1950s; it is true that the minimum prior to Solar Cycle 19 was long and low.

Tree Tyree, N6TR, of Boring, Oregon, sent his thoughts concerning the comments made by Bill Van Alstyne, W5WVO, of Rio Rancho, New Mexico W5WVO from the November 21, 2008 edition of the Solar Update. Tree also had some things to say about antennas for next weekend's ARRL 160 Meter Contest:

"I agree strongly with the concept of being a big station on 6 meters can be done much easier than 20 meters. A couple of points: E-skip is often high angle and an antenna on 6 meters at 30 feet is very competitive. When I worked Europe during the ARRL June VHF QSO Party, my 45 foot antenna was better than the one I had at 95 feet.

"If someone has a modest tower -- say a tri-bander on a 60 foot tower -- they actually have a very competitive antenna system for 160 meters staring them in the face. I recently took a 55 foot tower at N6TW's place in Silverton, Oregon, that had a Force-12 40-10 meter beam on it; with about two hours of work, I turned it into an antenna that enabled QSOs with Europe and Japan, even without a kilowatt. As it turns out, towers in the 55-80 foot range with a beam acting as a top hat turn out to be very close to a quarter wavelength. Gamma matching this is pretty straight forward. I typically use some old coax as the gamma wire, suspended about 18-24 inches from the tower, going up perhaps two-thirds of the way. You can get good performance with as few as 8 ground wires (the longer the better, but there is no magic length. The wires are detuned when you lay them on the ground).

"Use a variable cap to see if your gamma is working, and if you can, use a transmitter as your SWR meter (AM broadcast stations often interfere with the readings you see using an SWR meter). Don't be surprised if you see a pretty broad SWR curve." I think Tree means to tune the gamma match with the variable capacitor for best transmitter output, or "maximum smoke," as it is sometimes called. Find details on this kind of feed system for 160 meters here, here, here and here.

Tree continues: "This is basically the antenna I have used for 20 years now to work more than 200 countries on 160 meters. Certainly it isn't the best choice for a receive antenna, but if you are in a quiet location, you would be surprised at what you can hear with good conditions (that we are currently enjoying on Topband)."

Next weekend's ARRL 160 Meter Contest would be an excellent weekend to test this out. Why don't you try it?

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.