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 20, 2011   
   To all radio amateurs    
      
   SB PROP ARL ARLP020   
   ARLP020 Propagation de K7RA   
      
   A decline in sunspot activity this week showed as a 23 point drop in   
   average daily sunspot numbers, and nearly 9 point decline in average   
   daily solar flux.  These compare, of course, to the numbers for the   
   previous reporting week, which always runs from Thursday through   
   Wednesday.   
      
   But with this decline in activity there were three new sunspot   
   groups on May 14, and then one new sunspot group each day following,   
   through May 18.  But on May 19, there was no new sunspot group, and   
   the daily sunspot number declined from 65 on Wednesday to 36 on   
   Thursday.  Heightened geomagnetic activity occurred from May 15-17,   
   with the planetary A index in the low double-digits.   
      
   The latest prediction from NOAA/USAF is for much lower solar flux   
   than predicted on Wednesday, May 18.  The forecast predicts solar   
   flux readings of 84 and 82 on May 20-21, then 80 on May 22-26,   
   jumping to 90 on May 27 and 110 on May 28-30.  Predicted planetary A   
   index is 7 on May 20-21, 5 on May 22-25, then 8, 22, 18, 15, 15 and   
   8 on May 26-31.   
      
   Geophysical Institute Prague predicts quiet conditions May 20-21,   
   quiet to unsettled May 22, and quiet May 23-26.   
      
   On Wednesday, May 18 the solar flux was predicted at 92 on May   
   20-26, much higher than numbers forecast a day later and referenced   
   above.   
      
   Last week's Propagation Forecast Bulletin ARLP019 mentioned that   
   most sunspots lately appear in the Sun's northern hemisphere, but on   
   May 19 they are all in the southern hemisphere.  Go to   
   http://spaceweather.com/ and on the upper right check the archive   
   for May 18.  Note the two sunspot groups, 1214 and 1216, in the   
   southern hemisphere.  Now change to May 19, and note sunspot group   
   1218, also in the southern hemisphere.  On May 20 it shows all   
   sunspots only in the southern half.   
      
   Today the new June 2011 issue of WorldRadio Magazine is available   
   online, for free.  Go to http://www.worldradiomagazine.com to   
   download the latest issue, and check out Carl Luetzelschwab, K9LA's   
   propagation column on pages 30-33.  He gives an interesting treatise   
   on solar flux and sunspot numbers.   
      
   The only mail this week was from K4FNC, and is not the usual type of   
   question about propagation, but he asked, "Can you tell me when is   
   the best time to make contact with the space station on 2 meters or   
   the 440 frequencies?"  Quite a bit of information on ARISS is on the   
   ARRL web site at   
   http://www.arrl.org/amateur-radio-on-the-international-space-station.   
      
   If you click on the "Frequently Asked Questions" link on the left   
   side, this gives you a lot of the details, such as how to track the   
   space station.  The link to AMSAT at   
   http://www.amsat.org/amsat-new/tools even gives a method for   
   tracking that doesn't need your own tracking software.  Click on   
   Online Satellite Pass Predictions, select ISS, and enter FM05nb for   
   the grid square for K4FNC, click Predict, and this gives the time   
   for AOS (Acquisition of Signal) and LOS (Loss of Signal) for his   
   location.   
      
   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://mysite.ncnetwork.net/k9la/index.html.   
      
   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 12 through 18 were 29, 29, 64, 54, 63, 57,   
   and 65, with a mean of 51.6. 10.7 cm flux was 92.8, 91.5, 91.4,   
   94.5, 92.2, 91.5, and 90.6, with a mean of 92.1. Estimated planetary   
   A indices were 3, 4, 4, 11, 12, 10, and 6, with a mean of 7.1.   
   Estimated mid-latitude A indices were 2, 3, 3, 9, 10, 8, and 4, with   
   a mean of 5.6.   
   NNNN   
   /EX   
      
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