Hunt for unique Iridium flare

From: Denis V. Denissenko (denis@hea.iki.rssi.ru)
Date: Thu May 30 2002 - 08:40:17 EDT

  • Next message: Bjorn Gimle \(TietoEnator\): "Re: Hunt for unique Iridium flare"

    Hello List,
    
    Two years ago I've taken pictures of two Iridium flares between Jupiter
    and Saturn: Aug. 12th (http://hea.iki.rssi.ru/~denis/ir20000812.html,
    separation 7.5 degrees) and Sep. 27th
    (http://hea.iki.rssi.ru/~denis/ir20000927.html, 10.5 degrees).  Now it's
    time for something more difficult!  There's a series of flares in Ursa
    Major near (or between) Alcor and Mizar observed in central Russia these
    days.  Two stars are 12 arcminutes (0.2 degree) apart, so the pass can
    only be visible from a very narrow band on Earth.  Rough calculations
    show it should be a few (appr. two or three) kilometers wide (780km/57/5
    without taking into account height above the horizon).  This thing is
    yet more rare than Lunar transits (visible diameter of the Moon is 2.5
    times larger).
    
    This morning I tried to observe the best flare like this for my
    location.  The case was very difficult 'cause Sun was only 7.5 deg below
    horizon, but under pretty clear skies both stars were easily seen with
    the naked eye.  The -6 mag flare materialized very close to dimmer
    (4.0m) Alcor but I'm afraid Iridium 7 passed above it.  I guess I have
    missed it "scoring a goal" by a couple of kilometers - instead of going
    to a darker place in the park 1 km north from my home I should have
    headed south.  I even took a 25-30 sec exposure with 3.5/50 lense and
    400 film.  Let's wait and see what I got there.
    
    Go to http://hea.iki.rssi.ru/~denis/iridmsk.html and click on 5-30
    3:35:33.7 flare to see sky chart.  The next flare will be 5-31
    3:29:26.3.  I am 4 hours ahead of UT.
    
    The question is: can anybody plot the path of visibility of this rare
    events or generate the table with the longitudes and latitudes of
    southern and northern limits?  Is there a software for predicting
    visibility maps of Lunar transits also available?
    
    By the way, coordinates of two stars are:
    R.A. = 13h 24m 02.1s, Dec. = +54o55'02" (Mizar),
    R.A. = 13h 25m 20.1s, Dec. = +54o58'48" (Alcor).
    
    Denis in Moscow
    
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