The K7RA Solar Update
We experienced a bit of a scare this week when four days went by without sunspots. That's right -- for the first time in three months, we saw more than a single day with a sunspot number of 0, and that last period was back during November 23-December 8. Until March 6, there were just three days since then without sunspots, each a bit less than two weeks apart: December 25, January 6 and January 19. Sunspot numbers for March 4-10 were 40, 35, 0, 0, 0, 0 and 12, with a mean of 12.4. The 10.7 cm flux was 81.3, 79.5, 78.3, 76.6, 76.3, 77.9 and 80.3, with a mean of 78.6. The estimated planetary A indices were 6, 2, 3, 4, 3, 2 and 7, with a mean of 3.9. The estimated mid-latitude A indices were 4, 1, 3, 3, 1, 2 and 6, with a mean of 2.9.
On Wednesday, sunspot group 1054 emerged in the northeastern quadrant of the visible solar disc, and just south of the center of the field another sunspot group appeared on Thursday, number 1055. This brought the sunspot number from 12 on Wednesday to 31 on Thursday, March 11. The total area covered by sunspots increased 14 times from Wednesday to Thursday. NASA's STEREO mission shows a possible third sunspot group possibly appearing over the horizon in a few days. As of 0300 on March 13, we can see 88.23 percent of the Sun thanks to STEREO; two weeks later the coverage will expand to about 88.42 percent. We should see 90 percent coverage on June 18 around 2323-2335 UTC.
The 45 day forecast for solar flux has been shifting over the past few days. On March 9, it predicted solar flux for March 12-22 at 78, falling to 75 after March 23. On March 10, it shifted to 84 on March 12, 86 March 13-18 then 78 on March 19-22. On March 11 -- the latest available for this bulletin -- it changed to 85 for March 12-15, 83 on March 16, 81 on March 17 and 80 on March 18-19. Check here for the latest forecast. The new daily forecast appears sometime after 2100 each day.
Current planetary A index prediction from the same source shows the value at 5 on March 12-13 and 7 on March 14-15, then back to 5. Geophysical Institute Prague says watch for quiet conditions March 12-13, quiet to unsettled March 14-15, unsettled March 16 and back to quiet for March 17-18.
David Moore, a shortwave listener in Morro Bay, California, regularly sends us articles of interest to readers. About 10 days ago he sent us this article from Astronomy Now about a project at the Royal Observatory Greenwich involving the public in an effort to analyze solar data. Don Kalinowski, NJ2E, of Cary, North Carolina also sent a link to this project, called Solar Stormwatch. Their idea is that there is too much data for the scientists to observe, so they hope to use a recently popular concept called "crowdsourcing" in which large numbers of people can expand the observatory's capabilities. This definitely sounds like a fascinating endeavor for many of our readers.
We received lots of reports about good conditions for the ARRL International SSB DX Contest last weekend. Andy Gudas, N7TP, of Amaragosa Valley, Nevada, worked all continents in a half hour on 40 meters with 100 W and a simple wire antenna, an inverted vee.
Scott Bidstrup, TI3/W7RI sent a link to an interesting article in Science News about predicting sunspot minima by studying magnetic flows.
Jon Jones, N0JK, in Kansas, noted e-skip a bit early for the normal season. On March 9 at 2320, he worked K2EK, from EL88 in Florida; around 90 minutes later, at 0052 on March 10, he worked AC5O from EL49 in Louisiana. Jon was in his car, but using a 5/8 wave 2 meter whip. He notes that March normally has the lowest occurrence of e-skip of any month of the year. He also reported that W0WOI in Iowa heard the TI2NA beacon in Costa Rica at about 0115 that day. Mike Schaffer, KA3JAW, in EL87 (Tampa, Florida), reported receiving TV signals from Central America around the same time. Around 2300, he heard YNTC, TV2 in Nicaragua. The strongest signals were around 2325, and gradually faded away around 2500.
Bob Alsaker, N7HJL in Phoenix, Arizona wrote: "I received my first license in 1960 (Novice call WV6NTQ) and have been active most of the 50 years since then (except for my 'vacation' in Vietnam). Back then, working all around the world was expected, even with modest equipment (50 W or less) and minimal antennas (ground mounted verticals with no radials). The past few months have been a real joy again, after what has seemed like an eternity with no sunspots and no DX. The recent ARRL CW DX contest was once again a blast! More than 50 countries -- with 9 new ones added to my DXCC. For all the hams licensed in the past decade, get ready for some real fun, especially if you like working DX. Us old-timers remember!"
All times listed are UTC.
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. 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.