Propagation

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SB PROP @ ARL $ARLP020 ARLP020 Propagation de K7RA

ZCZC AP20 QST de W1AW Propagation Forecast Bulletin 20 ARLP020 From Tad Cook, K7RA Seattle, WA May 18, 2012 To all radio amateurs

SB PROP ARL ARLP020 ARLP020 Propagation de K7RA

Look at the archive on http://www.spaceweather.com/. On the upper right side of the page, it is accessed by selecting a date on the three drop-down fields. Now step day-by-day through the past week to see the progression of a considerable number of sunspots. The spots are in the Daily Sun image on the left side of the page. There was one new sunspot group on May 10, two on May 11, four more on May 13, and another on May 15.

Average daily sunspot numbers for the past week rose nearly 25 points, or about 27%, to 117.3. The big day was Monday, May 14 when the daily sunspot number jumped to 156. This was the day after four new sunspot groups, numbered 1481 through 1484 arrived.

Average daily solar flux rose 12 points to 131, an increase of 10 percent.

For the near term, predicted solar flux is 135 on May 18-20, 130 on May 21-22, 125 on May 23, 120 on May 24, 115 on May 25-31, 120 on June 1, 125 on June 2-3, 130 on June 4, 135 on June 5-9, and 130 on June 10-12.

Projected planetary A index is 15 on May 18, 8 on May 19, 5 on May 20-22, 8 on May 23, 5 on May 24 through June 4, then 8, 12, 18, and 10 on June 5-8, 5 on June 9-11, and 8 on June 12-13.

Check out http://www.youtube.com/watch?v=yJu3a2C5zwo for a wonderful video of sunspot group 1476 as it transits the Sun over the week of May 5-11. The images also have a lovely orchestral accompaniment.

If you plan to be in Washington, DC on June 5, 2012, you may want to attend the Space Weather Enterprise Forum 2012, held at the National Press Club.

See details at http://www.nswp.gov/swef/swef_2012.html.

The "Monster Sunspot" (group 1476) is all over the news, and on the web as well at http://www.space.com/15736-monster-sunspot-solar-flare-satellites.html. Be sure to follow the story all the way down the page below the video.

A large scale photo of the spot - taken a week ago on May 11 - is at http://news.discovery.com/space/big-pic-sun-space-weather-sunspot-eruption-120511.html.

Don't miss a National Geographic article and photo gallery on solar activity at http://ngm.nationalgeographic.com/2012/06/solar-storms/ferris-text .

Sunspot size comparisons are all the rage this week, including this article from Universe Today: http://www.universetoday.com/95232/how-big-are-sunspots/.

Jim Hadlock, K7WA of Seattle, Washington is now in a limited antenna space, and just uses a couple of 17 meter mobile whips pointing out horizontally from a center feedpoint. Jim writes: "It's not that great an antenna - I often hear west coast stations working DX that I cannot hear myself. I check the band a couple of times a day for activity since I'm trying to work 100 DXCC entities this year (2012). Tuesday I worked number 50 (Scotland) and yesterday around local noon (1718Z) I worked Brunei. In addition to listening on the band for activity, the NCDXF Beacons at 18.110 MHz and W1AW at 18.0975 MHz provide a check on real-time propagation."

If you would like to make a comment or have a tip for our readers, email the author at, k7ra@arrl.net.

For more information concerning radio propagation, see the ARRL Technical Information Service web page at http://arrl.org/propagation-of-rf-signals. For an explanation of the numbers used in this bulletin, see http://arrl.org/the-sun-the-earth-the-ionosphere. An archive of past propagation bulletins is at http://arrl.org/w1aw-bulletins-archive-propagation. Find more good information and tutorials on propagation at http://myplace.frontier.com/~k9la/.

Monthly propagation charts between four USA regions and twelve overseas locations are at http://arrl.org/propagation.

Instructions for starting or ending email distribution of ARRL bulletins are at http://arrl.org/bulletins.

Sunspot numbers for May 10 through 16 were 93, 102, 85, 138, 156, 125, and 122, with a mean of 117.3. 10.7 cm flux was 130.7, 136.4, 129.5, 130.5, 130, 129 and 130.9, with a mean of 131. Estimated planetary A indices were 12, 12, 10, 12, 6, 5, and 9, with a mean of 9.4. Estimated mid-latitude A indices were 11, 10, 8, 10, 7, 5, and 8, with a mean of 8.4. NNNN /EX