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    Sun activity
    From: Richard B. Emerson
    Date: 2001 Sep 06, 6:21 AM

    Herbert Prinz writes:
     > Russell Sher wrote:
     > > [...]  I also heard on the local news that solar activity may affect satellite communications
     > > between now and October 15 - one wonders whether this could affect GPS
     > > signals.
     >
     > It is also likely to affect sextant navigation: While shooting the
     > sun, the navigator might become entranced observing the sun spots
     > and mess up the sight. Last week there were several so called
     > "naked eye sunspots" to be seen. To be sure, "naked eye" refers to
     > the size only and is not to be taken litterally. A sextant,
     > however, is a suitable observation instrument.
    
    While practicing on Monday while sailing up the Chesapeake, I did
    notice the last of Active Region 9601 towards the west limb of the
    Sun.  AR 9591 was comparable in size; AR 9601 was just barely visible
    in my 6x monocular so I think these groups were "close but not quite".
    It's been a while since a really large sunspot grouping ("naked eye"
    size) has formed but, particularly last summer, I have been able to
    point out "naked eye" sunspots as the Sun set, dimming its light
    significantly.  It's a surprise when people think "that dot" isn't a
    bird or cloud but a giant sunspot.  For those interested in observing
    the Sun safely, filters can be made with "Baader film", a safe and
    optically clean film developed in Germany.  Try Scope Stuff at
    http://www.scopestuff.com and drill down to the Baader film page.  An
    A4 sized sheet (7.9" x 11.4") of film costs $29.99.  Instructions for
    making custom filters with little more than card stock from manila
    folders and the film are included on the page.  A good web site for
    white light images of the Sun is
    http-://sohowww.nascom.nasa.gov/sunspots/
    and a good site for reports on overall space weather (e.g. risk to
    satellites) is
    http://www.sec.noaa.gov/SWN/
    
    Rick
    S/V One With The Wind, Baba 35
    

       
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