Tad "The Sun bursts through in unlooked-for directions" Cook, K7RA, this week reports:
Another week and still no sunspots. The 3-month moving average for daily sunspot numbers that we began reporting toward the end of Solar Cycle 23 seemed to retrospectively suggest that solar minimum occurred last fall. The daily average for the 3-month period centered on last October was nearly 3 -- or 2.967 to split some hairs. This is an average of the 91 daily sunspot numbers from September 1-November 30. Following that low, November was 6.85; from December 2007-April 2008, the 3-month average drifted from 8.14-8.89. With remaining Solar Cycle 23 spots becoming increasingly rare -- and barely any Solar Cycle 24 spots -- this suggested solar activity was stalling out. Then, at the end of June, a further decline when the 3-month average centered on May dropped to 5.04.
Sunspot numbers for July 3-9 were 0, 0, 0, 0, 0, 0 and 0 with a mean of 0. The 10.7 cm flux was 65.5, 65.4, 65.1, 66.1, 65.5, 65.5 and 66 with a mean of 65.6. Estimated planetary A indices were 4, 4, 7, 4, 3, 2 and 4 with a mean of 7.
Estimated mid-latitude A indices were 3, 3, 7, 5, 2, 1 and 3 with a mean of 3.4.
For more information concerning radio propagation, visit the ARRL Technical Information Service Propagation page <http://www.arrl.org/tis/info/propagation.html>. To read this week's Solar Report in its entirety, check out the W1AW Propagation Bulletin page <http://www.arrl.org/w1aw/prop/>.
| Notes | This solar update is brought to you courtesy of the American Radio Relay League's ARRL Letter. |