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21 November, 2007
This is an off-schedule bulletin before Thanksgiving.
Because ARRL headquarters is closed on Friday, the day this bulletin is
normally released, and this bulletin was written before the end of our
reporting week (which is Thursday through Wednesday), the sunspot, solar
flux and geophysical numbers normally at the end of this bulletin will
appear in a new propagation bulletin on Monday, November 26. Friday, November
30 will find us back on the regular schedule.
Another sunspot appeared in the past week, but just for two days, November
16-17. The sunspot number was 13 on both days.
Neil Klagge, W0YSE of Layton, Utah wondered why the last Propagation
Forecast Bulletin ARLP047 said there was only one sunspot on November
6 when the sunspot number for that day was 11. That is because of the
arcane method used to derive sunspot numbers. A sunspot number of 11 means
just one sunspot. The number is derived by counting 10 points for each
sunspot group, and adding one point for each spot. So 11 is also the minimum
non-zero sunspot number.
It is either 0, or 11, or something higher, with nothing from 1-10.
So in reality, this week when we said there was one sunspot for November
16-17, because the sunspot number was 13, that can only mean that there
was one group of sunspots, but three spots were observed, although they
were tiny.
We had some geomagnetic activity this week from a coronal wind stream.
On November 20 the planetary K index rose to 6 for one period, and the
planetary A index for the day was 28. Alaska's College A index was 48.
The predicted planetary A index for November 21-27 is 20, 15, 10, 8, 15,
10 and 5. Note that this weekend, November 24-25, is the CQ Worldwide
DX CW Contest. Sunspot and solar flux numbers should remain about the
same, with an occasional spot appearing, and solar flux hanging around
70 or slightly lower.
Jon Jones, N0JK noted some trans-equatorial 6-meter e-skip
propagation from Florida to Brazil on the evening of November 18. From
2358z November 18 through 0002z November 19, KE4WBO worked PY2XB. K4CVL,
also in Florida, worked P43A in Aruba on 6 meters at the same time, 0001z.
All reported good signals.
If you would like to make a comment or have a tip for our readers, email
the author at, k7ra@arrl.net.
For more information concerning radio propagation, see the ARRL Technical
Information Service at,
http://www.arrl.org/tis/info/propagation.html.
For a detailed explanation of the numbers used in this bulletin see,
http://www.arrl.org/tis/info/k9la-prop.html.
An archive of past propagation bulletins is at http://www.arrl.org/w1aw/prop/.
Monthly propagation charts between four USA regions and twelve overseas
locations are at, http://www.arrl.org/qst/propcharts/.
Source: The
American Radio Relay League
•
DX Spots popup
• All propagation
reports can be found at:
http://www.southgatearc.org/propagation
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