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The K7RA Solar Update


This reporting week -- March 12-18 -- there were no sunspots, but we saw a couple of promising magnetic anomalies which faded away before ever emerging as sunspots. Sunspot numbers for March 12-18 were 0, 0, 0, 0, 0, 0 and 0 with a mean of 0. The 10.7 cm flux was 68.7, 68.2, 68.5, 68.4, 69.4, 68.8 and 68.4 with a mean of 68.6. The estimated planetary A indices were 6, 16, 9, 7, 5, 3 and 1 with a mean of 6.7. The estimated mid-latitude A indices were 6, 10, 7, 5, 4, 3 and 0 with a mean of 5.

On Saturday, March 14, reported a sunspot that might have been emerging south of the Solar Equator. In addition to displaying an image from the Michelson Doppler Imager Project (SOHO/MDI), provided a link to images from Matthias Juergens in Germany. Juergens identified the images as evidence of "small flare activity" in the southeast. You can also see an image from Pete Lawrence, in West Sussex, UK, here.

Note the image in the first link shows the possible sunspot in the lower left quadrant of the visible solar disk; according to terrestrial mapping conventions, this places it in the southwest quadrant. Why is the solar convention opposite? I believe it is based on a mirror image of the earthly convention.

Instead of imagining yourself in space -- looking down at the Earth with west on your left and east on your right and then applying the same convention if facing the Sun -- imagine looking at the Sun from an earthbound perspective. Imagine a sunny day:You are lying flat on a lawn, facing the Sun with your body oriented so that your head is toward the north and feet toward south. Without actually looking at the Sun, your right side would be pointing west; if you raise your right arm to point to the right side of the Sun, according to convention that is also the west. So sunspots travel across the Sun (relative to Earth) from left to right, from east to west.

On Sunday, March 15, reported a blank Sun, but that "two proto-sunspots" were visible near the Sun's equator. But the next day -- and all week -- the Sun remained blank. The solar flux has been quite low, also.

If you check here for daily forecasts, you will see that every day the solar flux prediction has been a solid and unchanging 70 for the following 45 days. But solar flux values have actually declined slightly over the past few weeks. As reported above, the weekly average solar flux ending on Wednesdays for the period beginning February 19 and ending March 18 was 70.2, 69.5, 69 and 68.6. If you check the latest 45 day forecast (at the time of the writing of this bulletin was March 19), you will see that the predicted planetary A index for March 20-21 is 8, followed by a slightly quieter level of 5. The next moderate geomagnetic disturbance is expected April 9-10, with a planetary A index of 15 and 10.

By the time you read this, the vernal equinox has passed and it is spring in the Northern Hemisphere. The equinox is early on March 20 for much of the Western Hemisphere, at 1144 UTC (4:44 AM PDT and 7:44 AM EDT). This is a popular time of year for fans of HF propagation, with the Southern Hemisphere moving into the fall season and bathed in sunlight equal to the Northern Hemisphere.

Al Lorona, W6LX, of Arcadia, California, asked about transitions from one Solar Cycle to the next and what the overlap was like. If we want to take a look at the last transition -- from Solar Cycle 22 to Solar Cycle 23 -- you can inspect previous editions of this bulletin in 1996, the last solar minimum. Just click on "Show Older Bulletins", then "Propagation for 1996." You can see the weekly averages; in the fall of that year there were weeks with no sunspots. But in 1997, you can see the weekly averages rose substantially. Such is not the case right now.

Looking back to the ARRL International DX SSB Contest, Jeff Hartley, N8II, of Shepherdstown, West Virginia, wrote on March 7: "There were surprisingly good conditions, at least on 20 meters in the few hours I've operated in the ARRL DX Contest. On 20 meters at the start, the band was open fairly well to Japan and KL7RA was loud. J5UAG answered a CQ, and South America up to as far north as Cuba was loud, but by 2335 UTC the Brazilians and Argentinians were fading out here in favor of areas farther west; by 2355 UTC, almost all stations to the south were gone. But Hawaii was loud. Forty meters was open well only to southern and western Europe at 0100 UTC. At 1515 UTC, I started tuning across 15 meters that was only open to the south, but the opening kept improving as I tuned up the band with Caribbean stations becoming loud. I worked as far north as KP2M and FS5KA. V48M, who was S5 and not workable through his pile up, was S9 and easy 10 minutes later. P40A running 100 W was the loudest station I heard about 20 dB over S9."

John Coleman, K5JVC, of Oklahoma City, worked the same DX contest, using 5 W and a 31 foot vertical on 15 meters, which I guess would be about 5/8 wavelength on that band. On Saturday, March 7, beginning at 1335 UTC, he worked HI3K, VP5H, 6Y1V, HI3TEJ, VP2E, LT0H, LU2QC, P40A, KP2M, WP4U, PJ4G and VP8KF (the Falklands were loud!), with the last at 1938 UTC. On Sunday, he worked (starting at 1518 UTC) PJ2T, WP4SK, YN2NB, TI8M, CE4CT, TI5N, PY1KN, KH7X, KH6RC, CS2C (Europe!) and ZF2AM. CS2C was at 1934 UTC and ZF2AM at 2146 UTC. John wrote: "All stations were ebbing and flowing rapidly. I would wait a few minutes to see if where their signal was peaking over the course of 3-5 minutes, and if they were peaking above S2, I would pounce during the peak. Most peaks only lasted 10-20 seconds and then they were back in the noise."

Harvey Moskowitz, W2YWC, of Livingston, New Jersey, wrote: "I am working on 5 Band DXCC with only one contact needed for 10 meters to complete the cycle. I check 10 meters periodically daily, and the DX websites, as well. Sunday, March 8 openings to South America were apparent, and I worked OA4SS in Lima -- loud and strong for number 100! I also heard many signals from Brazil and Argentina with my 3 element beam and running 100 W) You never know!"

George Hall, W4BUW, of Taylors, South Carolina, also sent a report on 10 meter activity on March 8. He said he didn't spend much time on 10 meters, but did work OA4SS at 2106 UTC with S9 signals and LU7DAG at 2109, also S9. He heard many other stations on ten, but didn't bother to work them. Like several people who wrote this week, he thinks that may people will tune into a quiet band, and because they don't call CQ, they never know that it was actually open and think the band must be dead.

Brian Webb, KD6NRP, whom I believe is in Ventura County, California, wrote: "It's a good thing I read last week's propagation bulletin. On Saturday, March 14, I recalled that your propagation bulletin mentioned recent 10 meter openings between the US and South America. At about 2200 UTC, I decided to give 10 meters a try. I tuned around and found a CW station calling CQ. I answered and subsequently had a QSO with KH6ZM on Hawaii's big island. What a pleasant surprise! Although I have worked several stations on 10 meters via E-skip, this was my first long-range contact on that band." Brian has a very interesting Web site that has information on launches from Vandenberg Air Force Base.

I've noticed that sometimes I can see the antennas of readers who write in to the bulletin, via aerial photos. Just look up the street address online here and enter it with the ZIP code on the page. On many locations, an option called "Bird's eye" will appear. Click on this option and instead of a satellite photo and you can see a high resolution aerial photo taken from a low flying plane. In the upper left, you can use + to zoom in, and if you select another direction (it defaults to north), you don't just turn the image, but you actually see a different photo from a different perspective, often taken on a different day with different lighting conditions. For example, enter 225 Main St, 06111 for a view of W1AW.

Finally, Art Jackson, KA5DWI, of North Richland Hills, Texas, has an interesting and useful document on seasonal sporadic-E propagation, which will probably increase next month.

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 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.



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