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ARRL Propagation Bulletin ARLP010 (2009)

ARLP010 Propagation de K7RA

QST de W1AW  
Propagation Forecast Bulletin 10  ARLP010
From Tad Cook, K7RA
Seattle, WA  March 6, 2009
To all radio amateurs 

ARLP010 Propagation de K7RA

No new sunspots since the recent brief three-day appearance of
quickly fading sunspot 1013 on February 24-26.  It was another Cycle
24 sunspot, but not too encouraging, considering how brief and weak
it appeared.  There are no predictions for new sunspots, but these
events tend to occur suddenly.

In this bulletin we have been tracking our own flavor of smoothed
sunspot number, one based on a shorter period of data (three months
instead of one year that the official smoothed sunspot graphs are
based upon), perhaps revealing trends earlier.  But the trend goes
down again.  Now that February has passed, we can take sunspot data
from December 1 through February 28 to calculate a three month
average, centered on January.  The total daily sunspot numbers for
that period was 208, divide that by 90 days, and the result is 2.3.

Here are the numbers for the recent past, updated through last

Jan 07 22.7
Feb 07 18.5
Mar 07 11.2
Apr 07 12.2
May 07 15.8
Jun 07 18.7
Jul 07 15.4
Aug 07 10.2
Sep 07  5.4
Oct 07  3.0
Nov 07  6.9
Dec 07  8.1
Jan 08  8.5
Feb 08  8.4
Mar 08  8.4
Apr 08  8.9
May 08  5.0
Jun 08  3.7
Jul 08  2.0
Aug 08  1.1
Sep 08  2.5
Oct 08  4.5
Nov 08  4.4
Dec 08  3.7
Jan 09  2.3

Just as Cycle 23 had a double-peak, we are perhaps observing a
double bottom, centered on August 2008 and early 2009, or with the
second minimum perhaps some time in the near future.  We won't know
it until it has passed, but it sure feels like a minimum at the

The lack of sunspots has been gaining attention outside of the usual
scientific, amateur astronomer and amateur radio circles, and with
so many people commenting on it who have no familiarity whatsoever
with solar cycles and sunspots, we are bound to see poor judgment
passed on as settled fact.

For years, non-scientists (I am one too) have occasionally attempted
to correlate sunspot trends with everything from social unrest,
cardboard box production, and stock market averages, to climate and
hem lengths, with no success.  Or, at least the conclusions were not

A year ago, some of us witnessed up close the resulting flap when a
daily financial news organ grossly misquoted an astrophysicist,
claiming he had predicted decades of few if any sunspots,
accompanied by endless winter.  Even though the scientist denied
ever saying those things, the story seemed to develop a life of its
own, a sort of social virus that spread widely very quickly, nearly
impossible to correct.

As a long time fan of contemporary folklore, I thought it might be
interesting to track this particular meme, so I used a popular
search engine feature in which I registered a particular string (the
word sunspot, in this case), and every day it sent me a summary of
every new use of this word found on web sites, in blogs, Usenet
newsgroups, and newspapers, along with links to these articles.

One of the common mistakes I found involved the difference between
number of sunspots and sunspot numbers.  For instance, the sunspot
number is 11 if there is a single sunspot, and 23 if there are three
sunspots in two groups.  So someone looks at old sunspot records,
sees a sunspot number of 150 for a certain day, and assumes that the
appearance of 150 simultaneous sunspots in a single day is a common

Or they might take a look at a graph of smoothed sunspot numbers,
such as the one at, and
complain because the graph had recently changed without notice, or
that the graph at the current date was incorrect, because it showed
the cycle turning up, when that has not happened.

What they don't know is that every point on the graph is based on
the average of a year of sunspot data, and is placed in the middle
of that year.  So for any points within the past six months, up to
half are based on predicted data.  So if NOAA predicts sunspot
numbers to rise in the future, it is normal to see the graph rising
when in fact the sunspot numbers have not yet increased.  Some of
the erroneous accounts have pushed some sort of conspiracy theory,
claiming that "the government" doesn't want us to know how rare
recent sunspots have become.

Sometimes a letter to the editor of a newspaper, or a blog remark,
will state without attribution to any source, that the sunspot
number for a certain month was only 3.  They probably heard
somewhere that there were only three sunspots making an appearance
one month, when the actual average daily sunspot number for the
month was several times that.

On April 20, 2007 in Propagation Forecast Bulletin ARLP017 we told
you about Jeff Lackey, K8CQ of St. Simon's Island, Georgia (see and his HF rain
gutter stealth antenna.  At the time Jeff said that after less than
four months he had worked 121 countries in 33 zones with this

The antenna used his rain gutters and downspouts, and you can see a
diagram of the antenna in the March 2009 issue of CQ Magazine, on
page 52.  Included are a nice photo of Jeff, and another of the
tuning arrangement, which uses an automatic antenna tuner at the
base of the antenna.

The article says that Jeff has now worked 220 "DX entities" in 37
zones, less than two years later, and Jeff told us on Thursday that
the total is now 243/38, with 87 countries on 80 meters.  Jeff says
the gutter antenna is a tricky tune on 160 meters, but there he has
worked 34 states, 3 provinces and 7 countries.

Asram Chou, BV2WM of Taiwan is translating this weekly bulletin into
Chinese and posting it on the web at, and I used Google Language Services at to translate it back to
English, and was interested to see that even with the automatic
translation it was pretty close to the original.

Bob King, K7OFT of Seattle, Washington sent in an interesting link
to a December 2008 conference where multiple papers on the start of
Cycle 24 are stored.  See it at,

For anyone in Seattle this Thursday afternoon, March 12 at 3:30 PM
is a presentation at University of Washington's Johnson Hall in room
102 about probing the Earth's ionosphere with lightning.  See the
program schedule on the web at,
link.  With a map from,, you
can locate Johnson Hall.

This weekend is the ARRL International SSB DX Contest.  We can
assume conditions will include no sunspots and very stable
geomagnetic conditions. NOAA and USAF predict a planetary A index at
5 for March 6-12, and Geophysical Institute Prague predicts quiet
conditions, March 6-12.

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 26 through March 4 were 12, 0, 0, 0, 0,
0, and 0 with a mean of 1.7.  10.7 cm flux was 69.9, 68.9, 70.6,
69.4, 69.2, 69.1, and 69.7 with a mean of 69.5.  Estimated planetary
A indices were 2, 8, 5, 3, 2, 5 and 7 with a mean of 4.6.  Estimated
mid-latitude A indices were 2, 7, 4, 2, 0, 5 and 5 with a mean of


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