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ARRL Propagation Bulletin ARLP041 (1999)

ARLP041 Propagation de K7VVV

QST de W1AW  
Propagation Forecast Bulletin 41  ARLP041
From Tad Cook, K7VVV
Seattle, WA  October 8, 1999
To all radio amateurs 

ARLP041 Propagation de K7VVV

Solar flux and sunspot numbers were up this week, with sunspot
numbers almost double the week previous, but average solar flux up
less than six points.  Recent geomagnetic instability finally
quieted down, and on Wednesday morning UTC (Tuesday night in North
America) the K index at both the mid latitudes and the College Index
from Alaska were both zero.

Solar flux has been falling the past few days, after peaking at
146.2 on Tuesday.  The official daily numbers are always from the
2000 UTC reading at Penticton, British Columbia, but there are
readings at 1700 and 2300 UTC as well.  Following the 2000 UTC
reading on Tuesday, the flux for each of the three daily readings,
through 2000 UTC Thursday were 146.7, 139.6, 133.6, 132.1, 131.7,
and 129.4.

The projected flux values for the next seven days, Friday through
Thursday, October 14 are 130, 135, 140, 145, 145, 150, and 150.  The
projected A indices for the same dates are 10, 15, 25, 30, 20, 15
and 15.  Monday, October 11 looks like an unstable geomagnetic day.
October 24 could be a bad day as well.

W7AFC wrote to ask for an explanation of the various numbers
presented in this bulletin.  The last time this bulletin had a
detailed explanation of the meaning of the numbers was ARLP030.  You
can see it at on the
ARRL web site.

The path projections are intended to show the times when the bands
are most likely to be open to the target areas from the point of
origin, which changes every week.  There may be openings at other
times, but the periods shown are a very good bet for a strong

Sunspot numbers for September 30 through October 6 were 84, 67, 47,
117, 148, 160 and 176 with a mean of 114.1.  10.7 cm flux was 124.8,
121.6, 126.3, 134.5, 144.4, 146.2 and 133.6, with a mean of 133.1,
and estimated planetary A indices were 29, 11, 15, 10, 15, 16 and 6,
with a mean of 14.6.

The path projection for this weekend is from Billings, Montana.

To Europe, 80 meters 2300-0830z (peaking 0300-0530z), 40 meters
2100-1100z (peaking 0100-0600z), 30 meters open all hours, best
0000-0630z, weakest 1400-1730z, 20 meters 1300-0030z (strongest late
in the period), 17 meters 1400-2130z, 15 meters 1500-2030z, 12
meters 1700-1930z, 10 meters 1730-1900z.

To Southern Africa, 80 meters 0000-0400z (peaking 0130-0200z), 40
meters 2330-0430z, 30 meters 2200-0500z, 20 meters 2030-0500z, 17
meters 1800-0100z, 15 meters 1730-2100z, 12 meters 1630-2100z, 10
meters 1800-2000z.

To the Caribbean, 80 meters 2330-1100z, 40 meters 2230-1200z, 30
meters 2030-1400z, 20 meters 1230-0200z (stronger toward the end of
the period), 17 meters 1400-0100z, 15 meters 1430-0000z, 12 meters
1600-2230z, 10 meters 1800-2100z.

To South America, 80 meters 0030-1000z, 40 meters 0000-1030z, 30
meters 2300-1100z, 20 meters 2200-1100z, 17 meters 2000-0300z, 15
meters 1330-0200z, 12 meters 1400-0030z, 10 meters 1430-2330z.

To Australia, 80 meters 0830-1430z, 40 meters 0800-1530z, 30 meters
0730-1530z, 20 meters 0700-1700z, 17 meters 1500-1630z, 15 meters
2030-2200z and 0330-0500z, 12 meters 2100-0300z, 10 meters 2130-

To Japan, 80 meters 0730-1430z, 40 meters 0700-1530z, 30 meters
0600-1700z, 20 meters 2030-2200z and 0200-0600z, 17 meters 2030-
0330z, 15 meters 2100-0230z, 12 meters 2130-0030z, 10 meters 2200-

To Hawaii, 80 meters 0300-1430z, 40 meters 0200-1530z, 30 meters
0100-1700z, 20 meters 1400-0730z, 17 meters 1630-0400z, 15 meters
1700-0300z, 12 meters 1730-0130z, 10 meters 1800-0000z.

To Alaska, 80 meters 0030-1530z (best 0500-1230z), 40 meters and 30
meters very strong all hours, best 0330-1300z, weakest 1900-2130z,
20 meters 1500-1600z and 1800-0500z, 17 meters 1600-0330z, 15 meters
1700-0200z, 12 meters 1800-0030z, 10 meters 1930-2300z.


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