The K7RA Solar Update


This week, the average daily sunspot numbers remained about the same, with the number nudging up from 120.9 to 121.7, while the average daily solar flux numbers went from 136.5 to 137.5. For the past two weeks, the average planetary A index has been the same as the mid-latitude A index. Last week they were both 9.9; this week, both values were 8.

Sunspot numbers for May 2-8 were 102, 139, 156, 103, 122, 118 and 112, with a mean of 121.7. The 10.7 centimeter flux was 149.4, 147.9, 141.6, 137.1, 130.7, 128.7 and 126.9, with a mean of 137.5. The estimated planetary A indices were 13, 6, 5, 7, 8, 10 and 7, with a mean of 8. The estimated mid-latitude A indices were 11, 5, 5, 7, 9, 11, and 8, with a mean of 8.

The predicted solar flux for the near future is 125 on May 10, 115 on May 11-13, 110 on May 14, 105 on May 15-16, 110 on May 17, 120 on May 18, 130 on May 19-20, 135 on May 21-22, and then rising to 160 on May 28. The predicted planetary A index is 5 on May 10-11, 8 on May 12-13, 5 on May 14-20, then 15, 10 and 15 on May 21-23, 5 on May 24-27 and 15 and back up to 10 on May 28-29.

At 0119 UTC today (May 10), I received an alert from (not to be confused with The message (and the website) is in Dutch (there is also an English version of the website), and it looks like it says there was a “Class M3.95” solar flare, but the message does not say whether the flare was geo-effective (Earth directed) or how long it lasted. I note that says the flare was just over the Sun’s eastern horizon, so it was not aimed at Earth, but it will move toward Earth “in the days ahead.” An event on the eastern horizon should take about a week to move into a position where it is aimed toward Earth, although another variable is the latitude of the region. As I look at the English version of, I see a group of six graphs at the top; five of them cover the previous two hours, and the planetary K index covers the previous 24 hours.

David Moore sent a link to Phil Plait’s “Bad Astronomy” blog that featured an article and an impressive NASA video showing a May 1 solar event, as seen from SOHO, SDO and STEREO. “Bad Astronomy” refers to Plait’s attempts to correct popular misconceptions about science.

Lance Collister, W7GJ, of Frenchtown, Montana, wrote about recent 6 meter adventures: “Well, I think the solar flux index being over 145 on Saturday (May 4) probably moved the trans-equatorial propagation further north than usual -- and with the early onset of E-skip, which just happened to connect me to Texas just at the right time late in the afternoon -- I got my first ionospheric link to South America on TEP this solar cycle. On Saturday, I completed SSB and CW contacts with Uruguay, Argentina and Brazil. The next day, the solar flux index was still over 135 and I worked Chile weakly on CW, although I didn’t seem to have a good strong E-skip link like on Saturday. I’m still searching for Ecuador, Bolivia and Suriname.”

Paul Harden, NA5N, of Socorro, New Mexico. wrote about a fascinating project at the Very Large Array (VLA), the world’s largest radio telescope: “I am an electronics engineer at the VLA. My current project is our low-band system (60-500 MHz) and the Long Wavelength Array (LWA) for 10-88 MHz. Though a few years away, one of the science goals of LWA is to make real time 3D maps of the ionosphere. The prototype system clearly paints the locations of the E/F layers and its depths as it migrates around. This is really cool, and when completed, it should be made publicly available on the web. What a great tool for hams!”

Jay Miller, N4NUI, of Sandy, Utah, wrote about what happened on 6 meters on May 2: “During the afternoon, there was a great opening on 6 meters. From the QSOs that I could hear, it was obvious that there were many paths open to the north and south. I was mobile up in Antioch, Illinois (grid square EN52wk), and I heard stations to the southeast down to Southern Florida and southwest to West Texas. It was pouring rain and I couldn’t get out of the vehicle to tune the manual screwdriver without getting soaked to the bone. I fixed that problem this afternoon (May 3) by driving up to Milwaukee and bought a new mobile antenna. I got it on the vehicle in time to make a contact in the early evening with K5WLT in Texas and WP4O in Florida -- both with good signals, just as the opening started to close. Let’s hope this is a harbinger of things to come this summer. I travel for my job and I am sure glad I haul around an HF rig and a magnetic mount for the rental cars. A traveling ham using rental cars has to ask for the same rental models each time once one finds out how to get through specific firewalls to the battery.”

Floyd Chowning, K5LA, of El Paso, Texas, wrote on May 4: “I had a nice contact on 144.2 MHz SSB this morning with Duane Hansen, WA7KYM, in Cheyenne, Wyoming. Cheyenne is 639 miles from El Paso. I am in grid square DM61 and WA7KYM is in DN71. This was my first contact with a Wyoming station.”

Jon Jones, N0JK, of Lawrence, Kansas, wrote on May 4: “There was an interesting opening today from the Midwest to South America. I was mobile (my wife was driving) on Kansas highway K-10 (just east of the K-7 intersection in Olathe) and I heard K3PA, K0HA and N0XA calling CQ or calling some of the DX. I didn’t hear any DX until 2150 UTC, when PY3RO showed up on 50.115 MHz SSB. He worked a ham in Kansas City and I called after their contact. I had a quick contact with him, and he peaked to 5 × 7. During our contact, another ham in Kansas City came up on frequency and said my transmit audio was bad, which it is, due to voltage drop using a cigarette lighter plug to run the radio in the car; I normally use jumper cables directly off the car battery to run the radio. The next couple of times I went back to PY3RO and listened, the local kept telling me ‘OM, your audio is bad.’ I guess he didn’t hear the PY. This was my first contact with Brazil on 6 meters since 2001. I did not hear any other DX stations.”

Jeff Hartley, N8II, of Shepherdstown, West Virginia, wrote about great conditions back on April 7-11. He worked both Europe and Asia on 12 meters, and on April 9 -- on 10 meter CW running 5 W -- he worked 9A4WY in Croatia who gave Jeff a signal repot of S9 +10 dB: “Throughout the last month, except during disturbed conditions, 15 meters has been open to Europe for many hours, sometimes as late as 2200-2400 UTC, and open about 90 percent of the days to Indonesia with good signals from around 1300-1600Z. Each morning, 20 meters is consistent, with good signals from Australia from about 1115-1430 UTC or so, and long path to Southern Africa. On April 28, 15 meters was in good shape to Russia in the UA1DZ contest. I’ve logged quite a few stations in Northern Europe, as well as Kazakhstan and Asiatic Russia. Many stations in St Petersburg were active, and it was fun working them, as well as hearing them working each other.

“On the April 29-30 between 0200-0315 UTC (and running only 200 W), I had a huge number of Russian stations call on 20 meter CW. This was some of the most fun I have had -- and the largest number of Russian callers I have had -- in 40 years on the air; I logged more than 40 stations in an hour. On April 29, conditions were extremely good from Central Asia, all the way east to Germany. I logged all Russian call areas (except for 0), as well as a lot of Ukrainians and EX8AD in Kyrgyzstan. On April 30, conditions to Asia were not quite as good, but many stations in European Russia called in, including UA0YM in Zone 23. Earlier, around 2340-0030 UTC, there was a large increase in activity from Europe and the Middle East on 17 meter CW, where I logged Ukraine, the United Arab Emirates, Romania, Greece and Guernsey. On 20 meter CW, I logged Macedonia. There was a real air of excitement on both sides of the Atlantic over these great conditions.”

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.