QST de W1AW
Propagation Forecast Bulletin 54 ARLP054
>From Tad Cook, K7RA
Seattle, WA December 30, 2004
To all radio amateurs
SB PROP ARL ARLP054
ARLP054 Propagation de K7RA
Solar activity stayed about the same this week compared to the
previous period. Average daily sunspot numbers declined slightly
from 32.1 to 28. There weren't any disturbed days. Expect solar flux
to stay above 100 for the next 10-12 days. Recurring coronal holes
could cause a mild geomagnetic upset around January 2-3.
Geomagnetic Institute Prague predicts unsettled to active conditions
January 2 and 3, unsettled conditions December 31, January 1 and 4,
and quiet to unsettled conditions on January 5-6.
This week I finally got around to operating on the new 60-meter
band. Actually, the use of this band by radio amateurs has been
legal in the United States for almost a year and a half. This band
is unusual because operation is on upper sideband phone only, and
only on five fixed channels around 5.3 to 5.4 MHz. (See
I used an inexpensive mono-band 60-meter whip on my car, and found
the noise in the city to be quite high. I also found a 2:1 SWR after
adjusting the length of the whip. I listened to other stations
around the Western United States, and they also reported high noise
levels. I talked to a station in Arizona who said I had a good
signal from Seattle, which surprised me considering how inefficient
the 7 foot trunk mounted whip must be with a length of only 1/25th
wavelength. The band or group of channels actually, seems to be open
to many areas of the U.S. around the clock, with the strongest
signals during darkness and the weakest signals around mid-day.
After testing some varying parameters with a propagation prediction
program, this definitely looks like a good band for wintertime.
Running the same numbers over the path to Arizona from Seattle 6
months from now shows what must be a complete shutdown for about 8
hours centered on mid-day.
Keith O'Brien, N4ZQ is using a program called DX Atlas, by VE3NEA.
He asked about Effective Sunspot Number, a parameter used with this
program, and wondered how it differs from just plain Sunspot Number.
Over four years ago, Effective Sunspot Number was mentioned in
bulletin number 38, September 22, 2000. This is a value calculated
from real time ionospheric measurements. The value used to calculate
this is foF2, the highest frequency that a vertically radiated
signal is refracted by the F2 layer and returned to earth.
This definition of foF2 can be found on an interesting page
concerning sunspot counting methods at,
description of how Effective Sunspot Number is derived from foF2 is
on the Northwest Research Associates web site at,
There are a number of links to other interesting pages on the NWRA
Space Weather Services web site at,
Don't forget this Friday, otherwise known as New Year's Eve, is
Straight Key Night! This casual on-air event runs from 0000-2400z
on January 1, 2005. The emphasis is on having fun, ragchewing, and
keeping alive the tradition of operating CW the old-fashioned way. I
am going to use a beautiful old J-37 key and operate from my car.
See www.arrl.org/contests/rules/2005/skn.html for details,
and for soapbox comments from participants in the 2004 event, look
If you would like to comment or have a tip, email the author at,
For more information concerning propagation and an explanation of
the numbers used in this bulletin see the ARRL Technical Information
Service propagation page at,
Sunspot numbers for December 23 through 29 were 47, 42, 26, 16, 11,
27 and 27 with a mean of 28. 10.7 cm flux was 96.4, 97.2, 93, 91.7,
96.9, 105.2 and 98.5, with a mean of 97. Estimated planetary A
indices were 6, 4, 12, 10, 7, 16 and 18 with a mean of 10.4.
Estimated mid-latitude A indices were 5, 2, 6, 9, 6, 12 and 16, with
a mean of 8.
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