The K7RA Solar Update
SEATTLE, WA, Feb 17, 2006--Average daily sunspot numbers this
week rose by more than 7 points to 9, but this doesn't mean much. The Space Environment Center's Daily
Solar Data show how many days with a blank sun were noted over the past 30
days. Expect to see even longer stretches with no sunspots over the next year. A
couple of years from now we should see a new Cycle 24 rising faster than this
old one declined.
Scientists have known about sunspots for quite a while,
and Galileo sketched
them in the 17th century. The coolest part is the arrangement of the sketches
into a sort of flip-book animation, which you can view with any media player
such as Windows Media Player or Apple QuickTime. This gives us a
reproduction of what the sun was doing over the 35 days that Galileo made these
sketches. What a remarkable thing!
The ARRL International DX Contest (CW) is this weekend. Sunspot
854 is pointing straight at us, but it is tiny. Look for sunspot numbers and
solar flux to rise only slightly, if at all, and for quiet geomagnetic
conditions.
Based on the previous solar rotation, Wednesday, February
22 looks like it may show some fairly active geomagnetic conditions. Geophysical
Institute Prague predicts slightly different conditions, with February 19
unsettled to active, and February 21 and 22 just unsettled. The prediction is
for quiet geomagnetic conditions Friday and Saturday, February 17 and 18, only
slightly unsettled geomagnetic conditions on Sunday, February 19, and quiet to
unsettled geomagnetic conditions February 20 and 23.
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 February 9 through 15 were 24, 13, 11,
0, 0, 0 and 15, with a mean of 9. The 10.7 cm flux was 74.8, 75.2, 76, 76,
76.3, 77.3, and 78.5, with a mean of 76.3. Estimated planetary A indices were
2, 2, 6, 3, 2, 1 and 12, with a mean of 4. Estimated mid-latitude A indices
were 2, 2, 4, 2, 2, 1 and 7, with a mean of 2.9.
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.
Page last modified: 09:48 AM, 17 Feb 2006 ET
Page author: awextra@arrl.org
Copyright © 2006, American Radio Relay League, Inc. All Rights Reserved.
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