Tad "They have never seen the sunshine, nor the glory" Cook, K7RA, this week reports:
A sunspot emerged a few days ago, a welcome sight at Cycle minimum. Sunspot numbers for February 25-28 were 12, 13, 12 and 12, but that spot (number 983) is now gone over the eastern horizon of our Sun. If the February 29 sunspot number is zero, this means our three-month moving average of sunspot numbers centered on January will be 8.5, slightly higher than the last reading. Our moving average centered on June 2007-January 2008 is 18.7, 15.4, 10.2, 5.4, 3, 6.9, 8.1 and 8.5, with the minimum centered on October 2007.
Sunspot numbers for February 21-27 were 0, 0, 0, 0, 12, 13 and 12 with a mean of 5.3. The 10.7 cm flux was 71.8, 72.4, 71.6, 70.7, 71.4, 70.7 and 70.7 with a mean of 71.3. Estimated planetary A indices were 6, 4, 4, 3, 3, 3 and 12 with a mean of 5. Estimated mid-latitude A indices were 3, 3, 3, 2, 1, 2 and 6 with a mean of 2.9.
Remember that a sunspot number does not represent the actual number of sunspots. The minimum non-zero sunspot number is 11, because a value of 10 is counted for each cluster of sunspots; a value of one is added for each individual spot. So the February 26 sunspot number of 13 represents one group containing three sunspots.
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 >.
This week's "Tad Cookism" brought to you courtesy of Elizabeth Barrett Browning.
| Notes | This solar update is brought to you courtesy of the American Radio Relay League's ARRL Letter. |