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ARRL Propagation Bulletin ARLP024 (2009)

ARLP024 Propagation de K7RA

QST de W1AW  
Propagation Forecast Bulletin 24  ARLP024
From Tad Cook, K7RA
Seattle, WA  June 12, 2009
To all radio amateurs 

ARLP024 Propagation de K7RA

Sunspot numbers from May 31 through June 5 ranged from 13 to 23,
then the Sun was blank for two days, followed by sunspot numbers of
12 for both June 8 and 9.  This fleeting sunspot was number 1020,
and like last week's spot, 1020 had the magnetic signature of a new
Cycle 24 spot.  Alas, it was another of the frequent sunspots we've
seen lately which appear briefly, then vanish.

The last Cycle 23 spot was number 1016, which appeared April 29-30.

Leonard Halversen, WA2AMW of Princeton, New Jersey asked how Cycle
24 spots are differentiated from Cycle 23 spots, and we last
mentioned this in Propagation Forecast Bulletin ARLP044 from 2008,
so now is a good time to go over it again.

The sunspots have a magnetic signature.  As you watch them move from
left to right, they lead with a dark patch in front and a white tail
in the rear.  That is how Cycle 24 spots appear above the equator,
and it is just the opposite south of the Sun's equator.  Also, new
cycle spots tend to appear at higher northern or southern latitudes
away from the equator, while old cycle spots appear nearer the

Go to to look for
images.  Click on the "Search and Download Images" link, and select
MDI Magnetogram from the image types.  Try entering start/end dates
of April 28 and April 30 of this year, and click Search.  Select one
of the links from the middle of the list, and note that the sunspot
on the right side is near the equator, indicating a spot from the
old cycle, and that it leads with black on the right.  Because it is
slightly below the equator, this indicates a Cycle 23 spot.  If it
were above the equator, a Cycle 23 spot would lead with white on the
right side.

Now go back and search dates June 1 through June 3.  Note that you
can up the resolution to 1024 from 512.  Select one of these images,
and note the large sunspot above the equator has a Cycle 24

Still more comments arrived this week about how dead bands may be an
illusion.  Guy Cossette, VA2WT of Saint Roch de Mekinac in Quebec
wrote to tell us about his 80 and 40 meter operation.  Using 100
watts CW and a 40 meter dipole, he worked Crete, Cyprus and Tunisia
at 2200z and he also worked Cyprus on 80 meters at 2300z.

Ken Sturgill, WS4V in Marion, Virginia says he likes to use the
intelligent features at  If you wish, you can
set it for the countries you are looking for, and you can also set
it to only accept spots from tipsters in your country, so you get
the spots you can work.  He recommends hitting the "Tell Cluster"
button often, so the info isn't lost.  He also recommends reading
the manual.

Jim Sullivan, N7TCF of Phoenix, Arizona likes to use "DX Sherlock,"
at  He uses it to check out band
conditions, mainly on 6 meters.  One feature I like is the Es MUF
tab, where you can see the MUF in various places.  I believe this
data comes from ionospheric sounders (ionosondes), which fire a
sweeped RF signal straight up and then measure the strength and
frequency of the signals bouncing back.

Mark Lunday, WD4ELG of Hillsborough, North Carolina sent a link to a
nice map mash-up of 6 meter beacon stations at,  Mark wrote:

"I have also been experimenting with WSJT weak signal software from
Joe Taylor, K1JT.  It's pretty neat to tinker with meteor scatter on
6 meters, and very challenging with my modest station.  But I have
really gotten addicted to JT65A mode on 20 meters.  There always
seems to be somebody on the air in the vicinity of the calling
frequency of 14076 kHz, and I have worked some terrific DX that I
normally would struggle with from here with 20 watts.  I have also
heard DU on JT65A for the first time ever on any band or mode!  All
of my QSOs have been with 40 watts or less, mostly with 20 watts.
In just two months of part-time operation, I have worked 25
countries on JT65A including VK, JA, CX, lots of Europeans.  Also, I
worked ZS6 on 80 meter WSJT last weekend!  There were horrendous
thunderstorms all up and down the east coast, but the software
decoded just fine.  I could barely see the DX on the WSJT spectrum
waterfall, and decoded his CQ almost by accident while doing
something else in the shack."

For this week, geomagnetic conditions should remain very quiet.
Solar flux is estimated to be about 68, rising above 70 June 24
through July 1.

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 June 4 through 10 were 17, 13, 0, 0, 12, 12, and
0 with a mean of 7.7.  10.7 cm flux was 71, 70.1, 69, 68.9, 69,
69.1, and 69.2 with a mean of 69.5.  Estimated planetary A indices
were 6, 6, 5, 6, 4, 3 and 5 with a mean of 5.  Estimated
mid-latitude A indices were 5, 5, 2, 3, 2, 2 and 2 with a mean of 3.


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