Unk 90007 Observation

From: chester.geoff@usno.navy.mil
Date: Wed Jun 21 2000 - 10:53:50 PDT

  • Next message: Matson, Robert: "Red Iridium flare was explained"

    Ed, Rob, list members:
    
    I finally feel like I have somthing useful to contribute... :-)
    
    I was able to view Ed's Unk 90007 object last night from my front yard in
    Alexandria, VA (77.0725W, 38.8264N).  I searched for it with my home-built
    8-inch f/6 Dobsonian, finally acquiring it at 3:04 UTC.  It was probably
    already well into its flash cycle, since it was easy to spot just north of
    Iota Virginis, and the "primary" flash was easily brighter than the star
    (cataloged at 4.06).  I watched it continuously for the next 20 minutes,
    sometimes with 7X50 binox, sometimes with the telescope.
    
    The flashes appear to be quite complex.  The "primary" flash recurs about
    every 48 seconds.  It is very abrupt, similar to those from Superbird A.
    About 25 seconds after this flash, there is a "secondary" flash that is
    about a magnitude fainter,  This flash is preceeded by 2 "sparkles", about
    1/4 second duration, that appear about 1/2 second before the "secondary".
    One of these "sparkles" follows the secondary as well.  These "sparkles" are
    about 8th or 9th magnitude, and have a whiter color than the primary and
    secondary flashes, which are noticeably yellowih in tint.  This pattern
    repeated itself for some 10 minutes.  By 3:15 the brightness of the primary
    and secondary flashes started to fade, with the primary falling below 6th
    mag by 3:20.  At this point the "sparkles" diasappeared, and over the next 3
    cycles the secondary faded to invisibility.  The primary, however, changed
    characteristics from a "flash" to more like a "flare" of at least one second
    duration.  By 3:24 these, too, were becoming faint, and by 3:25 they were no
    longer visible in the telescope.
    
    The weather, of course, has socked us in again, but it looks like we may
    have a decent spate coming up towards the weekend.  I hope to get a
    "country" view in the 14.5-inch on Friday night.  By then I will have set my
    watch to USNO UTC.  I hope to get a better look at these interesting flash
    dynamics then.
    
    In the meantime, all you east-coast SeeSaters should try for this one.  It
    is definitely well worth watching!
    
    Cheers,
    
    Geoff Chester
    USNO Public Affairs Office 
    
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