This is a multi-part message in MIME format. ------=_NextPart_000_0005_01C549AD.E9773240 Content-Type: text/plain; charset="iso-8859-1" Content-Transfer-Encoding: 7bit SB PROP @ ARL $ARLP016 ARLP016 Propagation de K7RA ZCZC AP16 QST de W1AW Propagation Forecast Bulletin 16 ARLP016 From Tad Cook, K7RA Seattle, WA April 22, 2005 To all radio amateurs SB PROP ARL ARLP016 ARLP016 Propagation de K7RA Little changed in sunspots and solar flux this week, but it was one of those periods were average daily sunspot numbers were up slightly, and average daily solar flux was down a little. Average daily sunspot numbers were up over ten points to 50.9, and average daily solar flux was down five points to 81.9. Geomagnetic conditions were calmer and quieter, with no really stormy days at all. The most unsettled days saw planetary A index of 19 for April 14, while the mid-latitude A index was 14. On April 20 the planetary A index was 21 and the mid-latitude A index was 12. No large sunspots are detected on the sun's far side, and the projection for the next week is for more of the same in terms of solar flux and sunspot numbers. April 25-28 could see a slight rise in sunspot count. April 22-23 could produce some unsettled geomagnetic conditions if the interplanetary magnetic field turns south. Currently as this bulletin is written early Friday, the field points north, tending to deflect any solar wind. While there isn't much in the way of sunspots, at least conditions are quiet and there is more sunlight for those of us in the Northern Hemisphere. Randy Crews, W7TJ of Spokane, Washington sent a note in response to last week's bulletin mentioning 160 meter propagation. He writes, ''Here is one of the best articles on 160M Propagation I have read.'' The article appeared in CQ Magazine in 1998. Read it at http://solar.spacew.com/cq/cqmar98.pdf. Thanks to Randy for sharing it with us. If you would like to comment or have a tip, email the author at, k7ra@arrl.net. For more information concerning radio propagation and an explanation of the numbers used in this bulletin see the ARRL Technical Information Service propagation page at, http://www.arrl.org/tis/info/propagation.html. An archive of past bulletins is found at http://www.arrl.org/w1aw/prop/. Sunspot numbers for April 14 through 20 were 63, 61, 52, 54, 44, 43 and 39 with a mean of 50.9. 10.7 cm flux was 85.4, 84.9, 82.9, 83.6, 81.3, 78.2 and 77, with a mean of 81.9. Estimated planetary A indices were 19, 13, 7, 5, 8, 8 and 21 with a mean of 11.6. Estimated mid-latitude A indices were 14, 7, 4, 4, 5, 6 and 12, with a mean of 7.4. 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