The K7RA Solar Update

SEATTLE, WA, Apr 21, 2006--Geomagnetic activity was higher
over the past week, with the average daily planetary A index rising
over six points to 18. The most active days were Friday and
Saturday, April 14 and 15, when the planetary A index was 58 and
29. All this and auroras too were caused by a stiff solar wind
meeting an interplanetary magnetic field pointing south, making
Earth vulnerable.

Otherwise, geomagnetic activity has been low and should stay that
way. Sunspot numbers and solar flux should rise gradually,
reaching a peak around April 29 through May 3.

Predicted planetary A index for April 21-25 is 8, 8, 10, 8 and 8.
Geophysical Institute Prague predicts quiet to unsettled conditions
for April 21, unsettled conditions April 22-23, quiet to unsettled April
24-25, and quiet conditions April 26-27.

For this week's report we were missing solar flux data for April 18.
For some reason the report from observatory in Penticton, British
Columbia did not show any noon data on that date.

So we averaged the morning (75.4 at 1700Z) and afternoon (75.8
at 2300Z) readings with the solar flux from NOAA (74) and came up
with 75.1. At Penticton they measure the 10.7 cm solar flux three
times per day, at 1700Z, 2000Z and 2300Z, but it is only the local
noon reading at 2000Z that gets reported as the official flux value
for the day.

Several hams reported interesting or unusual propagation recently. Grant
Hollands, VA7GO of
Victoria, British Columbia (on Vancouver Island) reports that last week (April
12) he was sitting
on a bench on Mt. Tolmie (a park in Victoria) running 2.5 watts into a home made
whip. After
sunset around 0300z he heard a strong signal from W5QG in Texas on 14.21 MHz and
gave
him a call. W5QG gave him a 4x6 signal report. Then he worked ZK1JD at South
Solomon
Islands, who gave him a 3x4 report. Well, maybe none of that is unusual, but it
is nice to know
that running a couple of watts from a park bench using a whip antenna does allow
you to make
some contacts. Grant said that in February 2005 on 6 meter SSB using 2.5 watts
and a
handheld he worked Hay River in the Northwest Territories. Hay River is about
60.8 degrees
north latitude, 115.8 degrees west longitude. He notes that so far this year he
hasn't worked any
6 meter QRP DX.

Mike Giddings, G3XLB writes that even when the geomagnetic conditions were
acting up
recently, he still made contacts over long distances. Mike is in London, and
says that he couldn't
hear any North American stations on April 14, but worked Asia, Malaysia,
Cambodia and
Indonesia with reports over S9. Yet recently when the K index was low,
conditions seemed
worse.

For more information concerning propagation and an explanation of the numbers
used in this
bulletin see the ARRL Technical Information Service Propagation page. An archive
of past
bulletins is on the ARRL Web site.

Sunspot numbers for April 13 through 19 were 69, 62, 45, 45, 48, 46 and 38 with
a mean of
50.4. 10.7 cm flux was 80, 78.9, 78.4, 76.5, 77.9, 75.1, and 75.8, with a mean
of 77.5. Estimated
planetary A indices were 13, 58, 29, 10, 6, 6 and 4 with a mean of 18. Estimated
mid-latitude A
indices were 9, 32, 18, 8, 4, 5 and 2, with a mean of 11.1.
(K7RA, ARRL)

dxAce
Michigan
USA