SB PROP @ ARL $ARLP049   
   ARLP049 Propagation de K7RA   
      
   ZCZC AP49   
   QST de W1AW     
   Propagation Forecast Bulletin 49  ARLP049   
   From Tad Cook, K7RA   
   Seattle, WA  December 10, 2010   
   To all radio amateurs    
      
   SB PROP ARL ARLP049   
   ARLP049 Propagation de K7RA   
      
   Average daily sunspot numbers for the week were up over nine points,   
   to 35, and average solar flux rose over six points to 87.3. These   
   differences compare the dates December 2-8 with the previous seven   
   days. Average planetary A index declined 2.5 points to 2.1, while   
   average mid-latitude A index dropped 1.1 points to 1.6. These are   
   nice numbers, with higher sunspot numbers accompanied by lower   
   geomagnetic indices.   
      
   Predicted solar flux for the near term is right near or slightly   
   above the average for the past week, at 87, 87, 88, 88, and 88 for   
   December 10-14. Predicted planetary A index for December 10-14 is 8,   
   10, 10, 8 and 5.  Planetary A index is expected to remain around 5   
   from December 15-24.   
      
   Geophysical Institute Prague has a slightly different prediction for   
   the next seven days.  They predict unsettled conditions for December   
   10-11, quiet to unsettled December 12, unsettled December 13, quiet   
   December 14 and quiet to unsettled December 15-16.   
      
   Note the period of somewhat unsettled geomagnetic activity centers   
   around this weekend, the dates for the ARRL 10 Meter Contest,   
   December 11-12.  But only a mild increase in geomagnetic activity is   
   expected.  The Geminid meteor shower peaks December 13-14, and could   
   provide some ionized trails enhancing 10 meter propagation.   
      
   This year's 10 meter contest is the first time that Mexican states   
   will be counted as multipliers along with U.S. states and Canadian   
   provinces, as well as DXCC countries. You can see a map of the 32   
   Mexican states in PDF format at   
   http://www.dxxe.org/concurso/xe-mults.pdf.  Complete contest rules   
   are at http://www.arrl.org/10-meter.   
      
   Ten meters offers many opportunities for working Mexico from other   
   North American locations this weekend. For instance, Distrito   
   Federal, which includes Mexico City, should be workable from Salt   
   Lake City from 1730-1900z, and possibly from 1700-2100z.  The path   
   from the San Francisco Bay Area looks even better, with the   
   possibility of strong signals from 1700-2130z. From the Chicago   
   area, a likely opening is 1700-1830z, possibly open as early as   
   1630z and as late as 2000z. From Ohio the path looks good 1630-1930,   
   extending possibly 30 minutes early and an hour later. From   
   Winnipeg, Manitoba (VE4) the possibilities look excellent   
   1730-1900z, very good 1630-2030, and possibly extending to   
   1600-2100z.   
      
   If you want to use the predicted smoothed sunspot number with a   
   propagation prediction program for this month or next, you can find   
   the latest predicted values in the table on page 11 in issue   
   PRF-1840 at http://www.swpc.noaa.gov/weekly.  The values are updated   
   there about every 4-5 weeks.   
      
   You can also do a peek into the future, as this table shows a   
   predicted smoothed sunspot number for December 2010 of 38, 74 in   
   December 2011, and 89 in December 2012.  You can download W6ELprop   
   at http://www.qsl.net/w6elprop and run several instances of the   
   program at once, and flip back and forth, comparing projections for   
   2010 with 2011 and 2012.  The 10 meter possibilities expand   
   dramatically during periods of higher solar activity.   
      
   During the weekend the STEREO craft will surpass 97.95% coverage of   
   the Sun.  You can calculate an approximation of the coverage by   
   looking at http://stereo-ssc.nascom.nasa.gov/where.shtml and noting   
   the number at the bottom, "Separation angle A with B." When I look   
   at this early Friday morning, the number is 172.234, which   
   corresponds to about 97.84% coverage.  Subtract the separation angle   
   from 180, then divide by 360, subtract the result from 1 and   
   multiply times 100.  Or skip the subtraction from 1 to determine the   
   percent gap in the coverage.   
      
   To calculate the coverage at some time in the future, use the   
   "STEREO Orbit Tool" at http://stereo-ssc.nascom.nasa.gov/where.   
   Just use any date and time you want to test, and use the same method   
   described above.  At some point in early 2011 after STEREO reaches   
   100% coverage the gap will begin to grow again, but this time on the   
   earth-facing side of the Sun.  The image will be filled in with data   
   from the Solar Dynamics Observatory (SDO), which has a web page at   
   http://www.nasa.gov/mission_pages/sdo/main. In fact, the current   
   STEREO image (see http://stereo.gsfc.nasa.gov) already uses SDO data   
   for the Earth-facing side of our Sun, even though that may seem   
   redundant.  But this probably assures us that the transition to 100%   
   coverage will be seamless.   
      
   Randy Crews, W7TJ of Spokane, Washington lives 231 miles almost   
   directly east of my home in Seattle.  He's at the eastern end of   
   Washington state, 15 miles from the Idaho border.  Although his   
   latitude is slightly lower than mine, the exact beam heading is   
   slightly north of east at 89.3 degrees, instead of some fractional   
   amount south.  Why is this?  Because the shortest path is via the   
   great-circle route, and at 231 miles it is far enough to put the   
   path leaving my place just slightly north of east, even though he is   
   at 47.6017 degrees north latitude and I am at 47.6693 degrees north   
   latitude.   
      
   Randy has looked over his old station logs recently, and has   
   observations about the progress of Solar Cycle 24.   
      
   "Most don't realize how low we went in the Cycle 23/24 low: Previous   
   cycles began with a Sunspot Number of 10-12. This cycle began with a   
   Sunspot Number of about 1.5!   
      
   "Usually the cycle bottoms and picks right up within 12-13 Months   
   from the low. Not the case with Cycle 24.   
      
   "This cycle has yet to see the Solar Flux above 100. By comparison,   
   Cycle 22's official bottom was September of 1986, and as early as   
   April of 1987, Solar Flux Values were above 100 on many days (about   
   6 months later).   
      
   "With Cycle 24 (if you measure from the low of the lows (July/August   
   of 2008) we are past the 2 year point, measuring from October of   
   2009 (when the number of Cycle 24 spots exceeded the old number of   
   Cycle 23 spots) we are out over a year.   
      
   "I am grateful for what we have thus far. The High Bands are open   
   (17 meters consistently) which is a nice improvement and the higher   
   bands from time to time also which is a huge step from the long dry   
   spell in 2008.   
      
   "However, the bands have not really stepped into high gear. Flux   
   values consistently above 100 (years 2004/2005) would really move us   
   into the fast lane."   
      
   Thanks, Randy!   
      
   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 December 2 through 8 were 32, 27, 48, 47, 35,   
   34, and 22, with a mean of 35. 10.7 cm flux was 86.5, 86.8, 87.4,   
   87.9, 88.5, 87.1 and 87.2 with a mean of 87.3. Estimated planetary A   
   indices were 3, 1, 1, 1, 2, 4 and 3 with a mean of 2.1. Estimated   
   mid-latitude A indices were 1, 0, 1, 0, 3, 3 and 3 with a mean of   
   1.6.   
   NNNN   
   /EX   
      
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   Gentlemens' agreements ratified by IARU regions 1 and 2 have   
   designated a global "center of activity" frequency  in  each   
   of  the  international  hf  bands.  THese are similar to the   
   concept for weak signal calling and other center of activity   
   frequencies.  Three of these have been ratified worldwide.   
      
   THese  center of activity frequencies are where stations can   
   go to render or obtain emergency assistance.   
      
   WHen casually operating or  contesting  on  hf  please  make   
   yourself  aware  of  these  frequencies,  and give them some   
   space. Remember that often stations with emergency needs are   
   not  those  utilizing  high  gain antennas and maximum legal   
   power.   
      
   TO find out more, visit 14300.net or IARU web resources.   
      
      
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