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The K7RA Solar Update


Sunspot numbers from May 31-June 5 ranged from 13 to 23, then the Sun was blank for two days, followed by sunspot numbers of 12 for both June 8 and 9. This fleeting sunspot was number 1020, and like last week's spot, 1020 had the magnetic signature of a new Solar Cycle 24 spot. Alas, it was another of the frequent sunspots we've seen lately that appear briefly, and then vanish. The last Solar Cycle 23 spot was number 1016 that appeared April 29-30.

Sunspot numbers for June 4-10 were 17, 13, 0, 0, 12, 12 and 0 with a mean of 7.7. The 10.7 cm flux was 71, 70.1, 69, 68.9, 69, 69.1 and 69.2 with a mean of 69.5. The estimated planetary A indices were 6, 6, 5, 6, 4, 3 and 5 with a mean of 5. The estimated mid-latitude A indices were 5, 5, 2, 3, 2, 2 and 2 with a mean of 3. For this week, geomagnetic conditions should remain very quiet. Solar flux is estimated to be about 68, rising above 70 June 24-July 1.

Leonard Halversen, WA2AMW, of Princeton, New Jersey, asked how Solar Cycle 24 spots are differentiated from Solar Cycle 23 spots and we last mentioned this on October 24, 2008, so now is a good time to go over it again: The sunspots have a magnetic signature, and as you watch them move from left to right, they lead with a dark patch in front and a white tail in the rear. That is how Solar Cycle 24 spots appear above the equator; it is just the opposite south of the Sun's equator. Also, new solar cycle spots tend to appear at higher northern or southern latitudes away from the equator, while old solar cycle spots appear nearer the equator.

Go here to look for images (this is the same Web site where we pull the images of the Sun that you see on the ARRL Web page for these weekly Solar Updates). Click on the "Search and Download Images" link and select "MDI Magnetogram" from the image types. Try entering start/end dates of April 28 and April 30 of this year and click "Search." Select one of the links from the middle of the list and note that the sunspot on the right side is near the equator, indicating a spot from the old solar cycle -- see how it leads with black on the right? Because it is slightly below the equator, this indicates a Solar Cycle 23 spot. If it were above the equator, a Solar Cycle 23 spot would lead with white on the right side.

Now go back and search dates June 1-June 3. Note that you can up the resolution to 1024 from 512. Select one of these images and note the large sunspot above the equator has a Solar Cycle 24 signature.

Still more comments arrived this week about how dead bands may be an illusion. Guy Cossette, VA2WT, of Saint Roch de Mekinac in Quebec, wrote to tell us about his 80 and 40 meter operation. Using 100 W CW and a 40 meter dipole, he worked Crete, Cyprus and Tunisia at 2200 UTC; he also worked Cyprus on 80 meters at 2300 UTC.

Ken Sturgill, WS4V in Marion, Virginia, says he likes to use the intelligent features here. If you wish, you can set it for the countries you are looking for; you can also set it to only accept spots from tipsters in your country, so you get the spots you can work. He recommends hitting the "Tell Cluster" button often, so the info isn't lost. He also recommends reading the manual.

Jim Sullivan, N7TCF, of Phoenix, Arizona, likes to use DX Sherlock. He uses it to check out band conditions, mainly on 6 meters. One feature I like is the "Es MUF" tab, where you can see the MUF in various places. I believe this data comes from ionospheric sounders (ionosondes) that fire a sweeped RF signal straight up and then measure the strength and frequency of the signals bouncing back.

Mark Lunday, WD4ELG, of Hillsborough, North Carolina, sent a link to a nice map mash-up of 6 meter beacon stations. Mark wrote: "I have also been experimenting with WSJT weak signal software from Joe Taylor, K1JT. It's pretty neat to tinker with meteor scatter on 6 meters, and very challenging with my modest station. But I have really gotten addicted to JT65A mode on 20 meters. There always seems to be somebody on the air in the vicinity of the calling frequency of 14076, and I have worked some terrific DX that I normally would struggle with from here with 20 W. I have also heard DU on JT65A for the first time ever on any band or mode! All of my QSOs have been with 40 W or less, mostly with 20 W. In just two months of part-time operation, I have worked 25 countries on JT65A including VK, JA, CX and lots of Europeans. Also, I worked ZS6 on 80 meter WSJT last weekend! There were horrendous thunderstorms all up and down the East Coast, but the software decoded just fine. I could barely see the DX on the WSJT spectrum waterfall, and decoded his CQ almost by accident while doing something else in the shack."

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.



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