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Posting-Version: version B 2.10.1 6/24/83; site mgweed.UUCP
Path: utzoo!watmath!clyde!burl!ulysses!mhuxj!ihnp4!mgnetp!mgweed!rjr
From: rjr@mgweed.UUCP (Bob Roehrig)
Newsgroups: net.ham-radio
Subject: arrl propagation forecast bulletin nr 39
Message-ID: <12548@mgweed.UUCP>
Date: Mon, 24-Sep-84 19:28:02 EDT
Article-I.D.: mgweed.12548
Posted: Mon Sep 24 19:28:02 1984
Date-Received: Thu, 27-Sep-84 02:30:15 EDT
Organization: AT&T Consumer Products - Montgomery Illinois
Lines: 30


qst de k9eui
hr propagation forecast bulletin nr 39  from arrl headquarters
newington ct  september 24, 1984
to all radio amateurs  bt

solar flux levels of 75 or lower  september  13  to  20  almost
exactly  duplicate a significant low in april 1977, less than a
year from the end of cycle 20.  looking back to september  1975
shows  flux  high,  low  and  average  values to have been very
similar to those of september 1984 thus far.

these comparisons suggest that cycle 21 could be  shorter  than
the 11.2 year average, but flux records available (garble) show
that cycles 18, 19 and 20 all had brief periods of  substantial
sunspot activity in their final two years of life.

we may be on the verge of such a burst.  though visible sunspot
activity  has  been  very  low for the last two weeks, there is
action on the sun currently.  a  major  geomagnetic  storm,  in
progress  as  this  bulletin  was  being prepared, narrowed the
useable frequency spectrum  severely.   things  may  be  better
soon.  the solar region now facing us brought a flux rise to 93
four weeks ago.  such levels in late  september  and  in  early
october  could  work wonders for 21 and 28 mhz which could last
through about october 5.

american sunspot numbers  for  september  13  through  19  were
between 0 and 1 with a mean of 0.1  ar