Re: Daytime Iridium Flares?

From: Jim Scotti (
Date: Mon Apr 02 2007 - 17:34:44 EDT

  • Next message: Robin R. Wier: "Re: Daytime Iridium Flares?"

    Hi Bruce,
         Daytime Iridium flares are pretty challenging, but I have seen a couple 
    of them.  Here are a few tips.  First, pick flares either early in the 
    morning or late in the afternoon while the sun is low and as far away from 
    the flare as possible.  In this case, the sky will also be "darkest". 
    Ideally, you can find flares that happen near your zenith.  This leads into 
    the 2nd tip - try and precisely identify the spot on the sky that the flare 
    will appear.  They don't last long and it's easy to miss the flare against 
    the bright sky if you are not looking almost straight at it.  Translating 
    azimuth 122 and elevation 53 into the precise spot on the sky can be quite a 
    challenge without some careful advance preparation.  My most successful 
    daytime flares were observed very close to the zenith - giving me a very easy 
    spot to find on the sky and being seen through the least atmosphere overhead 
    where the sky was darkest.  Another thing you can do is practice by looking 
    for Venus in the daytime.  Right now is a great time since Venus is near its 
    evening elongation and should be easy to see (I've seen it a few times in the 
    last month or two while the sun was in the sky, though I haven't tried it at 
    mid-day lately - I used to look for Venus with a friend after lunch quite 
    often before he moved away).  One more thing - make sure your watch is tuned 
    so you know within a few seconds of when the flare will happen.
    Good luck!
    On Mon, 2 Apr 2007, Bruce MacDonald wrote:
    > I tried unsuccessfully to observe an Iridium flare during daytime today, and 
    > though it was forecast to be a mag -8 flare I could not see it at all in a 
    > clear and reasonably transparent sky.
    > Do any SeeSat subscribers have any tips on how to observe these elusive 
    > events?
    > Thanks in advance,
    > Bruce MacDonald
    > COSPAR Site 2751
    > Devizes, Wiltshire, United Kingdom
    > 51.3440 N 1.9849 W 125M (WGS 84) 
    > -------------------------------------------------------------------------
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    "Extraordinary claims require extraordinary evidence." - Carl Sagan
    Jim Scotti
    Lunar & Planetary Laboratory
    University of Arizona
    Tucson, AZ 85721 USA       
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