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ARRL Propagation Bulletin ARLP043 (2016)

ARLP043 Propagation de K7RA

QST de W1AW  
Propagation Forecast Bulletin 43  ARLP043
From Tad Cook, K7RA
Seattle, WA  October 21, 2016
To all radio amateurs 

ARLP043 Propagation de K7RA

Over the past reporting week (October 13-19) compared to the
previous seven days average daily sunspot number declined from 55 to
31, while average daily solar flux dropped from 101.9 to 83.4.

Planetary A index increased from 6.6 to 19.1, and average
mid-latitude A index jumped from 5 to 14.

This is the opposite of what happened two weeks ago compared to last
week, when A indices decreased but solar flux and sunspot numbers

The latest prediction for solar flux (from the October 20
prediction) shows these values: 75 on October 21-23, 72 on October
24, 75 on October 25-26, 80 on October 27, 75 on October 28-29, 80
on October 30, 85 on October 31 through November 5, 90 on November
6-8, 85 on October 9-11, 80 on November 12-14, 75 on November 15-19,
70 on November 20-22, 75 on November 23-25, 80 on November 26 and 85
on November 27-30.

Predicted planetary A index is 5 on October 21, then 22, 24 and 40
on October 22-24, then 44, 40 and 22 on October 24-27, 15 on October
28-30, 25 on October 31, 12 on November 1, 5 on November 2-5, 8 on
November 6, 5 on November 7-10, then 10, 24, 26, 12 and 8 on
November 11-15, 5 on November 16-17, then 12 and 22 on November
18-19, 35 on November 20-22, 20 on November 23, 15 on November
24-26, 25 on November 27, 12 on November 28 and 5 from November 29
to December 2.

Petr Kolman, OK1MGW of the Czech Propagation Interest Group sent the
following geomagnetic activity forecast for the period October
21-November 16, 2016.

"Geomagnetic field will be:

"Quiet on November 7-8
Mostly quiet on November 3-4, 9-11, 15-16
Quiet to unsettled on October 21, November 1-2, 5-6, 14
Quiet to active on October 22-23, 29-31, November 12-13
Active to disturbed on October 24-28

"Amplifications of the solar wind from coronal holes are expected on
October 22-31, November 5-6, 11-13."

Here is a web article about a nearby star which seems to exhibit
sunspot activity:

Another solar article, but this one regarding our own Sun:

Reader Roger Larson, KF6IVA of Harrison, Maine says he uses an
inexpensive alternative to solar telescopes called the Sunocular. A
week ago he sent this message: "You can buy a special pair of
binoculars (Sunoculars, 8x32 binoculars with a special coating) that
allow you to observe the Sun. I can see a big sunspot headed off to
the western limb, other that the Sun is featureless."

A week later he wrote: "The Sun was featureless yesterday. With
these 'sunoculars' you can make out large sunspots and therefore get
an idea of how active the Sun is. I have seen specialized solar
telescopes which would show more due to their higher magnification
but they cost a thousand dollars plus."

Here is the last correspondence from Roger, received just as I was
completing this bulletin:

"They work pretty well realizing that they are only good for
observing the Sun. I imagine that you've looked at the Moon with
binoculars, the Sun is roughly the same angular dimensions (30 arc
minutes).  The Moon has a lot of features visible in 8 power
binoculars, the Sun is featureless unless there's a large
sunspot(s). Along the edge of the Moon you'll see some 'rainbow'
effects due to imperfections in the lens unless you look with
expensive binoculars. Well there are a few of these rainbow effects
visible in the Sunoculars no worse than any other binoculars I've
used. The objective lens are coated with a material that allows
ten-millionth (1x10-5) of the light to pass through. The Sun appears
about as bright as a full Moon in them."

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 More good
information and tutorials on propagation are 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 October 13 through 19 were 41, 38, 35, 25, 23,
24, and 31, with a mean of 31. 10.7 cm flux was 95.3, 92.8, 84.9,
80.9, 76.2, 77.4, and 76.5, with a mean of 83.4. Estimated planetary
A indices were 43, 24, 11, 18, 20, 11, and 7, with a mean of 19.1.
Estimated mid-latitude A indices were 30, 20, 8, 13, 12, 10, and 5,
with a mean of 14.


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