ARRL

ARRL Propagation Bulletin ARLP026 (2008)

SB PROP @ ARL $ARLP026
ARLP026 Propagation de K7RA

ZCZC AP26
QST de W1AW  
Propagation Forecast Bulletin 26  ARLP026
From Tad Cook, K7RA
Seattle, WA  June 20, 2008
To all radio amateurs 

SB PROP ARL ARLP026
ARLP026 Propagation de K7RA

We are lucky to see at least one sunspot this week, although it is
only one.  Sunspot 999 is currently in its most geo-effective
position, near the center of the sun, as we see it.  This is another
old cycle 23 spot.  The sunspot number for the last few days has
been 11, which is the minimum non-zero sunspot number.  A value of
ten is assigned because there is just one cluster of sunspots,
although in this case it is a cluster of just one.  A value of one
is added to that for the single spot.  A week ago the sunspot number
was 13, which means one cluster, three spots, although the judgment
of the number of spots inside sunspot 999 is somewhat subjective.

Let's compare a couple of solar photos from last summer which
illustrate the subtle difference between a sunspot number of 12, and
sunspot number of 14.

On July 3, 2007, the daily sunspot number was 12.  Here is a photo
of sunspot region 961:
http://www.bcsatellite.net/bao/NOAA10961-3jul-1.jpg

Compare that to August 25, 2007, when the sunspot number was 14, in
this image of sunspot region 969:
http://www.bcsatellite.net/bao/NOAA10969-25-CaK.jpg

The August photo looks like 969 might have three dark areas, but a
daily sunspot number of 14 means there were four spots in one
region.

The July photo appears to show two dark areas, which is consistent
with a daily sunspot number of 12.

Next week is ARRL Field Day.  On June 28-29 there are no predicted
geomagnetic upsets.  The predicted planetary A index for June 27-29
is 8, 5 and 5.  Maybe we'll get lucky and see a sunspot or two.
There is a very good chance that conditions could be much as they
were last year, with fairly low geomagnetic activity (although the
predicted activity for this year is lower) and no sunspots.

A Portuguese group, Associacao de Radioamadores da Vila de Moscavide
sent a link (http://www.arvm.org/index_fd2008.html) to their recent
Field Day photos.  In Europe Field Day is held earlier than the ARRL
Field Day.  Note that on the page at the bottom there are links to
past Field Day images (see page bottom) and links at the top of the
page go to photos taken by a number of different hams.

Mike Williams, W4DL of Pompano Beach, Florida (EL96) mentioned that
last weekend's ARRL June VHF QSO Party produced great results for
him.  He said the spectrum scope on his rig made 6 meters look like
20 meters.  He wrote, ''It was incredible; I worked numerous
stations from here in EL96 on CW and also SSB, and AM.  I checked 2
meters and snagged K8GP there and 10 minutes later on 6.  The 6
meter band was open early in the morning on Saturday and was still
going strong at 0000Z that evening.  Love the QRM on 6 meter CW!''

Ken Sturgill of Marion, Virginia sent in a tip about 6 meter
activity on June 13.  Go to http://www.vhfdx.net/spots/index.php and
set variable 1 to 50 MHz, variable 3 to Reported from 13 June to 14
June 2008 and Show Only QSO above 5000 km, variable 4 to 1000, then
hit Submit Query.  This shows a slew of six meter contacts over long
distances, mostly via multi-hop e-layer propagation.  Of course you
can vary the parameters however you want, and if you lower the Show
Only variable you will see more e-skip that is not multihop.  Looks
like a dramatic six meter opening that day.

Jon Jones, N0JK sent in some six meter spots from last weekend, and
also some info on six meter sporadic-e propagation.

Go to http://www.uksmg.org/e107_plugins/wrap/wrap.php?5 and under
Six News Categories, select 6M Propagation Theories.  Select the
fourth listing, ''a primer on sporadic-E''.  See
http://www.uksmg.org/content/rattling.htm for an older article on
the subject.

Steve Lybarger, NU7T of Sparks, Nevada sent in this link to an
interesting article about dipole patterns in solar coronagraphs at
solar activity minimum:
http://sohowww.nascom.nasa.gov/pickoftheweek/old/05oct2007/

If you would like to make a comment or have a tip for our readers,
email the author at, k7ra@arrl.net.

For more information concerning radio propagation, see the ARRL
Technical Information Service at
http://www.arrl.org/tis/info/propagation.html.  For a detailed
explanation of the numbers used in this bulletin, see
http://www.arrl.org/tis/info/k9la-prop.html.  An archive of past
propagation bulletins is at http://www.arrl.org/w1aw/prop/.  Monthly
propagation charts between four USA regions and twelve overseas
locations are at http://www.arrl.org/qst/propcharts/.  Instructions
for starting or ending email distribution of this bulletin are at
http://www.arrl.org/w1aw.html#email.

Sunspot numbers for June 12 through 18 were 13, 13, 0, 0, 11, 11,
and 11 with a mean of 8.4.  10.7 cm flux was 67.1, 66.5, 67.1, 66.5,
65.3, 65.9, and 65.4 with a mean of 66.3.  Estimated planetary A
indices were 3, 3, 16, 20, 13, 9 and 9 with a mean of 10.4.
Estimated mid-latitude A indices were 2, 1, 16, 14, 10, 8 and 8,
with a mean of 8.4.
NNNN
/EX