Tad Cook, K7RA, Seattle, reports: No sunspots appeared last week. The previous 7 days had only one big sunspot group on one day, and the sunspot number was 35. Over the 7-day period, this averaged out to a sunspot number of 5, so average daily sunspot numbers declined from 5 to 0 this week. The average daily solar flux also declined, from 69.5 to 68.5.
Geomagnetic indicators were quiet, with average daily planetary A index declining from 5.1 to 4.1, and mid-latitude A index from 5 to 4.7.
Predicted solar flux is 70 on May 14 – 31; 68 on June 1 – 13, and 70 on June 14 – 27. Predicted planetary A index is 5 on May 14 – June 8; 8 on June 9 – 10; 5 on June 11 – 13; 10 and 8 on June 14 – 15, and 5 on June 16 – 27.
Sunspot numbers for May 7 – 13 were 0, 0, 0, 0, 0, 0, and 0, with a mean of 0. The 10.7-centimeter flux was 68.7, 67.9, 71, 67.9, 66.2, 68.9, and 68.8, with a mean of 69.5. Estimated planetary A indices were 4, 4, 3, 5, 5, 4, and 4, with a mean of 5.1. Middle latitude A index was 5, 4, 3, 5, 7, 5, and 4, with a mean of 5.
A comprehensive K7RA Solar Update is posted Fridays on the ARRL website. For more information concerning radio propagation, visit the ARRL Technical Information Service, read "What the Numbers Mean…," and check out K9LA’s Propagation Page.
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