ARRL Propagation Bulletin ARLP008 (2009)

ARLP008 Propagation de K7RA

QST de W1AW  
Propagation Forecast Bulletin 8  ARLP008
From Tad Cook, K7RA
Seattle, WA  February 20, 2009
To all radio amateurs 

ARLP008 Propagation de K7RA

On February 11-13 we saw a sunspot, then it was gone.  Typical of
sunspots recently, it was only seen briefly, and this one was a
relic of Cycle 23 according to its magnetic signature.  For at least
a couple of years now we've been expecting Cycle 23 to bottom out
and new Cycle 24 spots to emerge, but the sunspot minimum drags on.
Most projections are based on past cycle activity, so according to
the timing of past solar minimums, we keep thinking surely soon
there will be an explosion of new solar activity, but the Sun seems
to tease us.

Our recent experiment with a 3-month moving average of sunspot
numbers (see Propagation Forecast Bulletin ARLP006 at, for the latest
update) points to August 2008 as the possible solar minimum.  If it
turns out to be the end of Cycle 23, that would make 23 nearly 12
years long, only a little longer than the less-than-eleven-year
average cycle length.

Tomas Hood, NW7US has a nice image showing the transition from Cycle
23 to Cycle 24 sunspots at,  I believe the vertical
axis represents number of actual sunspots per month, rather than
sunspot number, which is entirely different.

Tomas Hood's website at has information on radio
propagation, and you can also hear his twangy guitar when you go to
that page.

Geomagnetic conditions were quiet this week, although February 14-15
saw moderate activity.  The middle-latitude Fredericksburg A index
was just 9 and 6 on those days, and the Planetary A index was 14 and
10.  The high-latitude College A index measured near Fairbanks,
Alaska was 25 and 22, indicating possibly disturbed conditions over
polar paths.  February 16-19 and possibly into today show very
stable and quiet indicators, similar to the January 7-8, 11-12,
21-25, and February 1-3, and 6-13 periods.  All those ones and
zeroes for K and A index tell the story at,

Geomagnetic conditions should continue to be quiet.  NOAA and the
U.S. Air Force predict a flat solar flux around 70 for the next
month.  The predicted Planetary A index for February 20-23 is 8, 12,
8 and 5, continuing at 5 until March 3, when it may rise to 10.
Geophysical Institute Prague predicts quiet conditions for February
20-26, except for unsettled conditions February 21-22.

There were a couple of bugs with some links in last week's
Propagation Forecast bulletin ARLP007.

The bulletin as displayed on the ARRL web site showed one of the
links, mms:// with the beginning
unhighlighted, so when users clicked to try to watch the VR2BG video
on OTH radar, they were instead taken to a similar address beginning
with http, which does not work.  Instead you can highlight the whole
URL including the mms beginning, hit Ctrl-C to copy, then open
another browser and paste the URL into the web address field by
clicking in the field and then hitting Ctrl-V, then the Enter key.
At least, this is how it works with Windows machines.

Similarly, the link,
although correct, caused the server to display an anti-hotlinking
error message as it detected the redirect from the ARRL web site.
This can be solved like the earlier problem with the mms URL.  Just
highlight the URL, then copy and paste it into another browser.
Works every time.  Thanks to George Mackus, AB0RX of Maryland
Heights, Missouri for alerting us to the problem.

Find more information on the Chain Home Radar system -- Jim Muiter,
N6TP, of San Mateo, California, recommended

Greg Andracke, W2BEE of Pine Plains, New York is off to Middle
Caicos Island (IOTA NA-002) from March 2-12 as VP5/W2BEE.  Greg will
be operating CW with just a doublet antenna, and if not on vacation,
perhaps he is there to film another documentary.  He is a
cinematographer (see and and recently I watched his excellent 2007
Academy Award winning documentary via a DVD from my local library.
Not sure which HF bands he will be on, but he said he will be
operating casually.

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, see the ARRL
Technical Information Service web page at,  For a detailed
explanation of the numbers used in this bulletin, see  An archive of past
propagation bulletins is at

Monthly propagation charts between four USA regions and twelve
overseas locations are at

Instructions for starting or ending email distribution of this
bulletin are at

Sunspot numbers for February 12 through 18 were 11, 11, 0, 0, 0, 0,
and 0 with a mean of 3.1.  10.7 cm flux was 69.7, 70.1, 70.1, 69.6,
69.5, 70.6, and 69.8 with a mean of 69.9.  Estimated planetary A
indices were 4, 3, 14, 10, 3, 1 and 2 with a mean of 5.3.  Estimated
mid-latitude A indices were 1, 2, 9, 6, 2, 1 and 1 with a mean of