The K7RA Solar Update


As reported in The ARRL Letter on Wednesday, six sunspot groups were visible, but that number shrunk to two on Thursday. Daily sunspot numbers declined from 84 to 29 over those two days as well, but the average sunspot number for the reporting week (Thursday, May 5 through Wednesday, May 11) grew by nearly 7 points from last week, to 74.6. Sunspot numbers for May 5-11 were 95, 71, 38, 61, 93, 80 and 84, with a mean of 74.6. The 10.7 cm flux was 104.9, 101.9, 102.2, 102.2, 103.7, 97.5 and 94.1, with a mean of 100.9. The estimated planetary A indices were 7, 4, 4, 2, 3, 8 and 6, with a mean of 4.9. The estimated mid-latitude A indices were 5, 3, 3, 0, 2, 5, and 7, with a mean of 3.6.

The latest forecast shows planetary A index of 10 for today (May 13), then 8 on May 14-16, 10 on May 17, 8 on May 18 and 5 on May 19-25. The next possibly big geomagnetic period is May 27, with a planetary A index of 22. The same forecast predicts solar flux of 95 on May 13-14, 90 on May 15-19 and 110 on May 20-30. Geophysical Institute Prague predicts quiet to unsettled conditions May 13, quiet May 14, quiet to unsettled May 15, unsettled May 16-18 and quiet to unsettled again on May 19.

On May 9, NASA released a slightly revised prediction for the peak of Solar Cycle 24, placing it at a smoothed sunspot number of 69 in June 2013. But just a month earlier, the estimate had a peak of 62 in July 2013. Last month, NASA was predicting this cycle as the weakest in 200 years, but the update places it as the weakest in the last century. These are Zurich sunspot numbers, which are always quite a bit lower than the NOAA SESC numbers that we report here. The NOAA numbers show a peak at 90 around February through July 2013.

On May 10, Rol Anders, K3RA, of Elkridge, Maryland wrote: “After a slow week or so, propagation has rebounded with extremely strong signals from Europe and Central Asia on 20 meters for several hours after their sunrise time. I heard many +30 and +40 dB signals here in Maryland. I think there have been a lot of tardy arrivals at work in Europe and Central Asia, as the hams have had difficulty pulling themselves away from such great conditions in the morning! Also, 17 meters has been very good in the evening with JAs and other Asian stations coming back to CQs 3 hours after sunset on the East Coast. Fifteen meters has been open to the Far East after sunset, as well. Most interesting was working JQ1QKK short path on 20 meter phone at 3 PM his time, 2 AM East Coast time!

“One ‘trick’ that I sometimes use to find openings is to look for ‘analogous openings’ at my latitude. If I can work a DX station close to my latitude at a certain time of the day, then it is likely that I’ll be able to work stations at that latitude the same distance away in the other direction, when my local time is the same as that first DX station’s was. Perhaps this is best explained by an example: The latitudes of JA and EX/EY/EZ/YA are not too different from Maryland, and they are both roughly the same distance away from me. So, if JQ1QKK in the example above was working me at 3 PM his time (2 AM my time), there should be an opening to the general EX/EY/EZ area from Maryland at 3 PM my time, 2 AM EX/EY/EX time. This can be extended to other latitudes if you know what DX stations at your latitude are working. For instance, if I hear stations at my rough latitude (EA, I, SV, EX, JA) working a path, I should have that same path when my local time is the same as theirs was when they experienced those paths. Of course, my path will be to an entirely different part of the world.”

Mark Bell, K3MSB, of Airville, Pennsylvania, wrote: “I had some nice 6 meter sporadic-E action here around May 3. I worked YV4DYJ in FK50 at 2253. Stations from Argentina were coming in quite strong the next two days.”

Jon Jones, N0JK, reports from Kansas that on May 5, he worked LU4FW on 6 meters with a sporadic-E trans-equatorial link. It was at 2138 and he was using an indoor dipole.

Rich Molinski, WB2KWF, of Smithfield, Virginia reported from FM16qw that on May 2, he worked 9Y4D and YV4DYJ on 6 meters using 80 W and a 3 element beam at 35 feet, with 5×3 reports each way. On May 6 he reported: “I was amazed at the propagation! It's nice to see 6 meters open up. Each night this week, 6 meters has been open to some degree.”

Bob Elek, W3HKK, in Central Ohio, reports an E-skip opening on May 5 on 6 meters. He reports: “A C6 was 59 +20 and had half the US calling him on SSB. Then for the first time in my 55 year ham radio career: TE skip to Argentina! Well, around dinner time in Ohio, on May 5, there it was. The 6 meter band was literally teeming with Argentine stations, mostly on SSB, from 50.1 to 50.13. LU after LU working pile ups, calling CQ, and coming in between 5×3 to 5×9 (on my 5 element Yagi 10 feet above my rear patio, equipped with the standard Armstrong rotator and fed by my 100 w rig). “At 2125, I worked LW3EX on 50.101 CW, then at 2133, I worked 9Y4VUX on 50.100 CW. At 2200, I worked LU9EEM on 50.120 SSB, all with signals between 57 and 59! In between, I tuned around for other countries and passed up on many LUs. Another local op worked VP8 (Falkland Islands), and a couple spots showed one station in Peru and Chile coming through, but I didn’t hear them. So, in summary, a very telescopic opening via trans-equatorial propagation into Argentina lit up 6 meters, and when things quieted down at around 2230, I left for dinner a little late -- but a very happy camper.”

Roger Gibson, K4KLK of Raleigh, North Carolina (in FM05), reports: “Six meters was open all day May 5 to WI area and then Florida. I was surprised to hear LU4FW (FF97) on my garage halo antenna. I quickly turned antenna south, then connected the 4 element quad antenna and got him on first call, with 100 W. Not many takers, but signals were very strong, 59+ and more like F2 with no fading. WE made contact made on 50.125 SSB at 2200 and he was in for several minutes.”

Both Larry Jacobson, K5LJ in Richardson, Texas, and George O’Brien, N4ZQ, in Dunedin, Florida, wonder why it seems that most sunspots appear in the Sun’s northern hemisphere in this cycle. I ran the by Carl Luetzelschwab, K9LA, who says that “hemispherical asymmetry of sunspots has been known and studied for quite a while. I don’t think there’s an air-tight explanation yet, but it is tied to the Sun’s conveyor belt. So what’s happening now is ‘normal’ in the sense that it’s been seen before in other cycles.” He noted that butterfly diagrams of Solar Cycle 20 show this predominance toward the beginning of the cycle, around 1965.

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 and 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.