The K7RA Solar Update

SEATTLE, WA, Nov 11, 2005--We may be in another period of zero sunspots. From October 24-28 there was a sunspot count of zero on each day. Three days at the beginning of the month were no-sunspot days, and four months ago there were five days--July 18-22--with no spots. A year from now expect to see longer periods of zero sunspot readings--possibly up to several weeks--based on what the periods between previous sunspot cycles were like.

Geomagnetic conditions should be fairly active today. Predicted planetary A index for Friday through Monday, November 11-14, is 15, 8, 5 and 5. The Prague Geophysical Institute predicts unsettled to active conditions on November 11 and 12, unsettled conditions on November 13, quiet to unsettled on November 14 and 15, and quiet conditions November 16-17. Remember that for good HF propagation we want these geomagnetic numbers to be low, with sunspot numbers as high as possible.

For more information concerning propagation and an explanation of the numbers used in this bulletin see the ARRL Technical Information Service Propagation page. An archive of past bulletins is on the ARRL Web site.

Sunspot numbers for November 3 through 9 were 24, 22, 18, 34, 31, 38 and 13, with a mean of 25.7. 10.7 cm flux was 76.8, 77.4, 79.3, 81.7, 79.4, 79.4, and 78.1, with a mean of 78.9. Estimated planetary A indices were 24, 20, 10, 10, 6, 3 and 3, with a mean of 10.9. Estimated mid-latitude A indices were 19, 16, 10, 12, 6, 2 and 1, with a mean of 9.4.

Amateur solar observer Tad Cook, K7RA, Seattle, Washington, provides this weekly report on solar conditions and propagation. This report also is available via W1AW every Friday, and an abbreviated version appears in The ARRL Letter. Readers may contact the author via e-mail.

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