The K7RA Solar Update
Our Sun was certainly quieter this week. The average daily sunspot numbers were down nearly 17 points to 51.6, while the average daily solar flux declined nearly 9 points to 83.2. Sunspot numbers for May 19-25 were 36, 33, 44, 47, 37, 23 and 23, with a mean of 34.7. The 10.7 cm flux was 84.4, 83.7, 83.6, 84.5, 84.1, 81.7 and 80.3, with a mean of 83.2. The estimated planetary A indices were 4, 3, 4, 4, 4, 6 and 4, with a mean of 4.1. The estimated mid-latitude A indices were 2, 2, 4, 3, 4, 5 and 2, with a mean of 3.1.
The latest prediction is for solar flux to remain low at about 85 on May 27-29, 80 on May 30-June 3, then rising to 90 on June 4, then 85 on June 5-7, and back to 90 on June 8-11, finally peaking at 95 on June 12. The same prediction has some geomagnetic activity this weekend, with planetary A index on May 27-30 at 10, 15, 12 and 10, then declining to 5 on May 31 and into the first week of June. The moderate activity on Saturday (May 28) is due to a solar wind stream. Geophysical Institute Prague predicts unsettled conditions on May 27, active conditions May 28, unsettled May 29-31 and quiet on June 1-2.
Things may seem quiet on this (the Earth-facing) side of our Sun, but a peek shows much more activity on the far side. All those white spots represent magnetic activity and some could indicate sunspot activity. If we assume that (depending partly on latitude) the Sun takes a little less than 28 days (approximately 27.5 days) for a single revolution relative to Earth, and there are 12 longitudinal sectors displayed, each one represents about 2.29 days, or about 55 hours. This can help you make a rough estimate of how long it takes an area on the far side to rotate across the horizon, which is at 90 degrees. Currently three sunspot groups (numbered 1216, 1222 and 1223) are visible, and another may be emerging.
Somehow I missed this announcement about the solar flux and geophysical announcements on WWV going away. Beginning September 6, there will be no more announcements at 18 minutes after the hour with solar flux, K and A index. This was reported on the ARRL website here.
Jeff Hartley, N8II, of Shepherdstown, West Virginia, sent a report on May 23: “There’s not much of an exciting nature to report, except that 15 meter openings to Europe seem pretty commonplace up to at least 2200 with very good signals, despite being well after dark (except in far Western and Northwestern Europe), despite the lower flux, which was 85 today. On Saturday, May 21, there was plenty of activity thru the day in the His Majesty King of Spain and UN DX contests on 15 meters from 1300 when I turned on the radio. There was the expected weakening of signals around noon, and then strengths increasing from 1900 thru the early evening. European signals on 20 were weak in the morning, which was pretty much expected due to the shift to summer conditions and increased absorption. Around 1330-1430, signals were good on 20 from Japan across to Kazakhstan, which was more active than usual with the Kazakhstan DX Contest. Around 2400, I again was active on 20 most of the time until 0300, with best signals from Kazakhstan in the 2400 hour and conditions gradually improved farther west with northern EU such as Lithuania, Sweden, Finland and European Russians, workable all with good signals, but some very fluttery. Between the European and Asiatic Russians and UNs, I was pretty busy running stations from 0200-0300, working a total of 15 Kazakhstan regions for the day (almost every station is in a different region). There was sporadic-E to the upper Midwest on Sunday around 0100, with one loud signal from EN32 in Iowa on 6 meters and several on 10 meters. Twelve meters is still frequently open to the south, including the Caribbean, through much of the day, starting around 1500.”
Jon Pollock, K0ZN, of De Soto, Kansas (EM28), sent this in on May 21: “The upper HF bands were excellent last night. I worked a bunch of Russian and European DX on 17 meters between 10 PM and midnight. The interesting part was 15 meters. At 11 PM CDT, I tuned the band and found three groups of digital signals around 21.070. Obviously, I have no idea what or who, but they were pretty strong. So I tuned up in to the phone band, this is now about 11:15 PM, and heard a ‘local’ rag chew between a couple of W4s and a W5. It sounded like backscatter. Then I heard K0FPL in Kansas City chatting with AB0RJ in St Louis via 250 mile back scatter path. I read the mail on their QSO, but no other signals on the band. It sounded very dead. Then I heard a ‘break,’ someone wanting to break into their QSO. It was a strong signal so I figured someone local. NOT!! It was E51CG in the Cook Islands! Holy Toledo! The Western Pacific! By now it was well after 11 PM CDT. Another case of 15 meters being ‘dead’ in the middle of the night. E51CG chatted with them for about 10 minutes and gave the locals, 10 dB over S-9 reports in Raratonga, Cook Islands! Trust me, the sunspots are back. Several guys have been commenting that they have not heard propagation like this in years and years. Could we be lucky enough to have another really big sunspot peak? I worked a KL7 in Western Alaska at 11 PM CDT on 15 meters CW last night. That is crazy stuff, compared to what we been seeing for years. Maybe after that crazy long multi-year cycle low, we are going to get a good one.”
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.