The K7RA Solar Update
We are lucky to see sunspot activity this week, although it is only one. Sunspot 999 is currently in its most geo-effective position -- near the center of the Sun -- as we see it. This is another old Solar Cycle 23 spot. The sunspot number for the last few days has been 11, which is the minimum non-zero sunspot number. A value of 10 is assigned because there is just one cluster of sunspots, although in this case it is a cluster of just one; a value of one is added to that for the single spot. A week ago, the sunspot number was 13, which means one cluster, three spots, although the judgment of the number of spots inside sunspot 999 is somewhat subjective.
Sunspot numbers for June 12-18 were 13, 13, 0, 0, 11, 11 and 11 with a mean of 8.4. The 10.7 cm flux was 67.1, 66.5, 67.1, 66.5, 65.3, 65.9 and 65.4 with a mean of 66.3. Estimated planetary A indices were 3, 3, 16, 20, 13, 9 and 9 with a mean of 10.4. Estimated mid-latitude A indices were 2, 1, 16, 14, 10, 8 and 8, with a mean of 8.4.
Let's compare a couple of solar photos from last summer that illustrate the subtle difference between a sunspot number of 12 and sunspot number of 14. On July 3, 2007, the daily sunspot number was 12. Look at this photo of sunspot region 961. Compare that to August 25, 2007, when the sunspot number was 14, in this image of sunspot region 969. The August photo looks like 969 might have three dark areas, but a daily sunspot number of 14 means there were four spots in one region. The July photo appears to show two dark areas, which is consistent with a daily sunspot number of 12.
Next week is ARRL Field Day. There are no predicted geomagnetic upsets on June 28-29. The predicted planetary A index for June 27-29 is 8, 5 and 5. Maybe we'll get lucky and see a sunspot or two. There is a very good chance that conditions could be much as they were last year with fairly low geomagnetic activity (although the predicted activity for this year is lower) and no sunspots.
A Portuguese group, Associação de Radioamadores da Vila de Moscavide sent a link to their recent Field Day photos. In Europe, Field Day is held earlier than the ARRL Field Day. Note that on the page at the bottom there are links to past Field Day images (see page bottom) and links at the top of the page go to photos taken by a number of different hams.
Mike Williams, W4DL, of Pompano Beach, Florida (EL96), mentioned that last weekend's ARRL June VHF QSO Party produced great results for him. He said the spectrum scope on his rig made 6 meters look like 20 meters. He wrote, "It was incredible; I worked numerous stations from here in EL96 on CW and also SSB and AM. I checked 2 meters and snagged K8GP there, and 10 minutes later on 6. The 6 meter band was open early in the morning on Saturday and was still going strong at 0000 UTC that evening. Love the QRM on 6 meter CW!"
Ken Sturgill of Marion, Virginia, sent in a tip about 6 meter activity on June 13. Go here and set variable 1 to 50 MHz, variable 3 to Reported from 13 June to 14 June 2008 and Show Only QSO above 5000 km, variable 4 to 1000, then hit Submit Query. This shows a slew of 6 meter contacts over long distances, mostly via multi-hop e-layer propagation. Of course you can vary the parameters however you want, and if you lower the Show Only variable you will see more e-skip that is not multihop. Looks like a dramatic 6 meter opening that day.
Jon Jones, N0JK, of Wichita, Kansas, sent in some 6 meter spots from last weekend, and also some info on 6 meter sporadic-E propagation. Go here, and under Six News Categories, select 6M Propagation Theories. Select the fourth listing, "a primer on sporadic-E." Check out this link for an older article on the subject.
Steve Lybarger, NU7T, of Sparks, Nevada, sent in this link to an interesting article about dipole patterns in solar coronagraphs at solar activity minimum.
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.