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ARRL Propagation Bulletin ARLP006 (1999)

ARLP006 Propagation de K7VVV

QST de W1AW  
Propagation Forecast Bulletin 6  ARLP006
From Tad Cook, K7VVV
Seattle, WA  February 5, 1999
To all radio amateurs 

ARLP006 Propagation de K7VVV

The geomagnetic field has been very stable over the past week, with
many periods when all of the planetary, Boulder and even high-
latitude K indices were zero.  Average planetary A indices, which
are based on the 3-hour K index over 24 hours, were down five points
to 4.4.  At the beginning of this month, the Boulder K index was
zero for 24 hours, resulting in an A index of zero for February 1.

Unfortunately, we not only saw low geomagnetic activity, but
declining solar activity as well.  The daily sunspot number on
Saturday was only 29, and it has not been that low since October 4
when it was 21.  Low activity like this means poorer conditions on
higher frequencies.  A southern California ham that the author spoke
with on 17 meters this week mentioned that solar activity has been
too low to enable many openings on 10 and 12 meters.

Since January has passed, it is time to review some monthly
averages.  The average daily solar flux for January was 142.4.  This
is a drop of almost eight points from December, which was 150.1.  It
is still a higher average solar flux than any month other than
December, 1998 in the current solar cycle.

For the near term look for better conditions and a rising solar
flux.  Predicted flux values for Friday through Sunday are 110, 115
and 115, and the predicted planetary A index for those days is 10, 8
and 8.  Beyond this weekend expect flux values to rise to around 120
by February 9, 130 by February 11, 140 on the 12th, 150 on the 13th,
and remain around 160 from the 14th through the 16th.  Look for
unsettled to active geomagnetic conditions around February 9-11.

There is good news from the SOHO mission this week.  SOHO is the sun
observing satellite that brought us so much great data and solar
images last year until problems began to develop in June.  This week
some new software was tried which allows SOHO to ignore the broken
gyroscopes which were the source of its problems, and instead track
stars to determine position.  Three spinning wheels now keep SOHO
oriented, and on Tuesday the craft returned to a position where it
is pointing toward the sun.  Check the latest on SOHO at  The first new images are at

In VHF news, Fernando Garcia, a TV DXer in Monterrey, Mexico
reported that last month was the best January for tropospheric
propagation that he has seen in his eight seasons of observation.
On January 10 with a Sony television and a dish he copied UHF
television signals from Georgia, and Georgia and Florida signals two
days later.  There were a total of eight days where he observed
signals over 1000 miles away, with signals from Tennessee and
Alabama as well as the ones mentioned above.

Sunspot Numbers for January 28 through February 3 were 37, 33, 29,
59, 36, 47 and 42 with a mean of 40.4.  10.7 cm flux was 118.8,
177.7, 118, 114.8, 118, 110.9 and 108.8, with a mean of 123.9, and
estimated planetary A indices were 7, 7, 5, 3, 2, 2 and 5, with a
mean of 4.4.


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