"Gamma Rays of Doom"

[Douglas.Minnema@dp.doe.gov]

    Are there any budding astronomers out there in RADSAFE land?  There is 
an 
    interesting article in the February, 1998, "Sky and Telescope" magazine 
    that I would like to get a second opinion on.  (Yes, this does have to 
do 
    with health physics!  Also, been offline a couple of months, sorry if 
    this is a repeat.)
    
    In the cover article, "Gamma Ray Bursts of Doom", the authors discuss 
the 
    implications of a hypothetical merging of binary neutron stars.  This is 

    one theory for explaining the occasional observation of gamma ray bursts 

    from distant galaxies.  The interesting part to me is their explanation 
    of what the consequences would be on earth if amerger occurred "in our 
    neighborhood", at a distance of 3000 light-years.  Let me quote the 
    article:
    
    "The first effect would be an extraordinarily bright gamma-ray bath, 
    briefly outshining the energy we receive from the Sun.  Most of this, of 

    course, would be invisible.  We would see a patch of sky glowing eerie 
    blue, the Cherenkov radiation resulting from interactions when the gamma 

    rays hit the upper atmosphere.  The patch might appear as bright as the 
    full Moon and a little larger in angular size."
    
    "the blast of gamma rays would ... produce enormous amounts of nitric 
    oxides... Within seconds the daytime sky might darken on the side of the 

    globe facing the burst, depending on the amount of pollution created." 
    [The article continues this thought by suggesting a version of the 
    nuclear winter theme.]
    
    A few days later the "subsequent cosmic-ray bath" arrives.  "The total 
    sea-level dose of muons would be roughly 100 times the dose lethal to 
    humans.  The muons would penetrate hundreds of meters underground and 
    underwater to kill all but the most well-protected or 
radiation-resistant 
    species."
    
    "the month long cosmic-ray blast will contain as much energy as 10 
    million years of normal cosmic-ray bombardment... it would leave ... 
    excesses of long-lived radioactive nuclei [such as] iodine-129, 
    samarium-146, lead-205, and plutonium-244"
    
    That should be enough to give you the idea.  Now, my question is, does 
    this make sense?  I would think that even 1/r^2 at 3000 light-years 
would 
    be a big help.  Would we really see a blue glow?  What is the lethal 
dose 
    from muons?  How does Pu-244 get produced from cosmic-rays?
    
    Any comments?
    
    Doug Minnema
    DOE
    
    Obviously not work related, but of professional interest (I hope).  As 
    usual, what few thoughts I have are truly my own.