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ARRL Propagation Bulletin ARLP020 (2012)

ARLP020 Propagation de K7RA

QST de W1AW  
Propagation Forecast Bulletin 20  ARLP020
From Tad Cook, K7RA
Seattle, WA  May 18, 2012
To all radio amateurs 

ARLP020 Propagation de K7RA

Look at the archive on On the upper
right side of the page, it is accessed by selecting a date on the
three drop-down fields. Now step day-by-day through the past week to
see the progression of a considerable number of sunspots. The spots
are in the Daily Sun image on the left side of the page.  There was
one new sunspot group on May 10, two on May 11, four more on May 13,
and another on May 15.

Average daily sunspot numbers for the past week rose nearly 25
points, or about 27%, to 117.3. The big day was Monday, May 14 when
the daily sunspot number jumped to 156. This was the day after four
new sunspot groups, numbered 1481 through 1484 arrived.

Average daily solar flux rose 12 points to 131, an increase of 10

For the near term, predicted solar flux is 135 on May 18-20, 130 on
May 21-22, 125 on May 23, 120 on May 24, 115 on May 25-31, 120 on
June 1, 125 on June 2-3, 130 on June 4, 135 on June 5-9, and 130 on
June 10-12.

Projected planetary A index is 15 on May 18, 8 on May 19, 5 on May
20-22, 8 on May 23, 5 on May 24 through June 4, then 8, 12, 18, and
10 on June 5-8, 5 on June 9-11, and 8 on June 12-13.

Check out for a wonderful
video of sunspot group 1476 as it transits the Sun over the week of
May 5-11.  The images also have a lovely orchestral accompaniment.

If you plan to be in Washington, DC on June 5, 2012, you may want to
attend the Space Weather Enterprise Forum 2012, held at the National
Press Club.

See details at

The "Monster Sunspot" (group 1476) is all over the news, and on the
web as well at
Be sure to follow the story all the way down the page below the

A large scale photo of the spot - taken a week ago on May 11 - is at

Don't miss a National Geographic article and photo gallery on solar
activity at .

Sunspot size comparisons are all the rage this week, including this
article from Universe Today:

Jim Hadlock, K7WA of Seattle, Washington is now in a limited antenna
space, and just uses a couple of 17 meter mobile whips pointing out
horizontally from a center feedpoint. Jim writes: "It's not that
great an antenna - I often hear west coast stations working DX that
I cannot hear myself. I check the band a couple of times a day for
activity since I'm trying to work 100 DXCC entities this year
(2012). Tuesday I worked number 50 (Scotland) and yesterday around
local noon (1718Z) I worked Brunei. In addition to listening on the
band for activity, the NCDXF Beacons at 18.110 MHz and W1AW at
18.0975 MHz provide a check on real-time propagation."

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 an explanation of the
numbers used in this bulletin, see An archive of past
propagation bulletins is at Find more good
information and tutorials on propagation at

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

Instructions for starting or ending email distribution of ARRL
bulletins are at

Sunspot numbers for May 10 through 16 were 93, 102, 85, 138, 156,
125, and 122, with a mean of 117.3. 10.7 cm flux was 130.7, 136.4,
129.5, 130.5, 130, 129 and 130.9, with a mean of 131. Estimated
planetary A indices were 12, 12, 10, 12, 6, 5, and 9, with a mean of
9.4. Estimated mid-latitude A indices were 11, 10, 8, 10, 7, 5, and
8, with a mean of 8.4.


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