Tad "Blazon sky blue and endow the Sun with gold" Cook, K7RA, this week reports:
We are lucky to see sunspot activity this week, although it is only one. Sunspot 999 is currently in its most geo-effective position -- near the center of the Sun -- as we see it. This is another old Solar Cycle 23 spot.
The sunspot number for the last few days has been 11, which is the minimum non-zero sunspot number. A value of 10 is assigned because there is just one cluster of sunspots, although in this case it is a cluster of just one; a value of one is added to that for the single spot. A week ago, the sunspot number was 13, which means one cluster, three spots, although the judgment of the number of spots inside sunspot 999 is somewhat subjective.
Sunspot numbers for June 12-18 were 13, 13, 0, 0, 11, 11 and 11 with a mean of 8.4. The 10.7 cm flux was 67.1, 66.5, 67.1, 66.5, 65.3, 65.9 and 65.4 with a mean of 66.3. Estimated planetary A indices were 3, 3, 16, 20, 13, 9 and 9 with a mean of 10.4. Estimated mid-latitude A indices were 2, 1, 16, 14, 10, 8 and 8, with a mean of 8.4.
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. |