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ARRL Propagation Bulletin ARLP055 (2005)

ARLP055 Propagation de K7RA

QST de W1AW  
Propagation Forecast Bulletin 55  ARLP055
From Tad Cook, K7RA
Seattle, WA  December 30, 2005
To all radio amateurs 

ARLP055 Propagation de K7RA

Average daily sunspot numbers rose over 22 points this week to 71.4,
and average daily solar flux was up by nearly 5 to 91.2. Not too bad
with the predicted solar minimum a year away. Over the past week
geomagnetic indicators were stable, but a solar wind caused the K
and A index to rise on December 27 and 28.

Sunspot and solar flux levels should remain approximately the same,
perhaps slightly lower January 1-4. Geomagnetic indicators should be
slightly unsettled for today, December 30, then quiet December 31 to
January 4, and quiet to unsettled January 5.

Next week we should have a look at the average sunspot numbers for
the year, comparing them with past years. So far, with only a few
days to go, it looks like the 2005 average daily sunspot number will
be nearly 30% less than in 2004.

Conditions should be good (little geomagnetic activity) for Straight
Key Night, the annual operating activity from 0000-2400z January 1.
So here on the West Coast it will run from 4:00 PM Saturday until
the same time on Sunday. This is a fun activity in which
participants use regular old-fashioned telegraph keys and often
vintage gear to communicate manually via Morse code. Details are at

Jaap Verheul, PA3DTR wrote in about Marcel Decanck, ON5AU and his
propagation web site at Jaap likes to
use the beacon logging page (click on "Beacons On-Line" on the left
side of the page) which shows which beacons from different locations
are currently being received at ON5AU in Belgium. You can get some
idea how your part of the world is being received in Europe on the
20 meter band and above by looking for signals from the beacon
station closest to you.

Red Haines, WO0W sent in some interesting links recently, including
the Propagation Page for the Radio Society of Great Britain. Many
nice links and resources on this page at,

If you would like to make a comment or have a tip for our readers,
email the author at,

For more information concerning radio propagation and an explanation
of the numbers used in this bulletin see the ARRL Technical
Information Service propagation page at, An archive of past
bulletins is found at,

Sunspot numbers for December 22 through 28 were 77, 47, 70, 77, 90,
78 and 61 with a mean of 71.4. 10.7 cm flux was 87.6, 93.1, 91.9,
91.8, 92.5, 92.3, and 89.1, with a mean of 91.2. Estimated planetary
A indices were 4, 1, 3, 6, 6, 18 and 14 with a mean of 7.4.
Estimated mid-latitude A indices were 4, 1, 2, 3, 3, 10 and 13, with
a mean of 5.1.


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