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The K7RA Solar Update

01/28/2011

The average daily sunspot numbers rose over the past week (ending January 26) by 11.3 points to 32.6, compared to the previous week, while the average daily solar flux rose 3.1 points to 83.5. The planetary A index average was down 2 points to 2.9, and mid-latitude A index was down 1.5 points to 2.4.

On Thursday, January 27, the sunspot number was 0, but a new spot is emerging near the horizon in the southeast quadrant. Sunspot numbers for January 20-26 were 32, 42, 36, 38, 28, 27 and 25, with a mean of 32.6. The 10.7 cm flux was 82.3, 87.5, 87.7, 84.3, 82.5, 80.5 and 80, with a mean of 83.5. The estimated planetary A indices were 3, 3, 2, 2, 3, 4 and 3, with a mean of 2.9. The estimated mid-latitude A indices were 4, 2, 3, 1, 2, 3 and 2, with a mean of 2.4.

The latest prediction from NOAA/USAF shows lower solar activity, with solar flux, for January 28 at 79, then 80 for January 29-February 6, 82 for February 7-22 and 88 on February 23. This forecast is from Thursday, January 28 and is much more optimistic than the Wednesday forecast, which was reported in The ARRL Letter on Thursday, January 27.

NOAA/USAF shows a planetary A index of 5 on January 28-February 2, then 8 on February 3, 12 on February 4 and 8 on February 5. Geophysical Institute Prague sees quiet conditions January 28 through February 1, quiet to unsettled February 2 and unsettled February 3.

This weekend is the CQ World Wide 160 Meter CW Contest, and geomagnetic conditions look stable, which is a favorable condition for this contest.

Ron McCollum, W7GTF, sent an image of the cover of the March 1956 issue of CQ Magazine that has a picture of a solar disc with sunspots with the headline “Sunspot Report: ONCE IN A LIFETIME CONDITIONS -- CQ EXCLUSIVE.” Of course, as we know, after this magazine appeared on newsstands 55 years ago, conditions got even better over the next couple of years.

Ron wrote: “While cleaning out our family home (of 41 years) in Seattle in preparation to sell, and to finally get rid of nearly 50 years of radio magazines, I kept this CQ.” What makes me nervous though is his statement “to finally get rid of.” Seattle has a very convenient and efficient recycling system that includes curbside pickup, which may make disposal a little too convenient. I certainly hope he found a good home for these journals. After all, they aren’t making any more of them. Most of the great old issues of QST from the 1920s and 1930s disappeared in World War II paper drives.

While not related to Amateur Radio or propagation, Dick Bingham, W7WKR -- who lives far off the grid at Stehekin, Washington (his station location listed in the FCC database is “1.2 miles up Company Creek Road”!) -- sent in a useful, interesting and educational link to a 15-part series on mathematics by Dr Steven Strogatz that appeared last year in The New York Times. This series focuses on a practical understanding of a wide range of mathematics for lay people, such as myself.

STEREO coverage, for all practical purposes, now displays the entire Sun. It recently passed 99.7 percent, and by February 1, it will surpass 99.8 percent coverage. Right now, you can only see a narrow slit of darkness on the Sun’s far side, and on Friday morning the new emerging sunspot region shows as a bright white area just this side of -90 degrees longitude in our Sun’s southern hemisphere.

Thomas Hood, NW7US, has a page on “De-mystifying HF Radio Propagation and Modeling” here. Here you can find some examples of coverage maps, which we covered in last week’s bulletin.

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 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.



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