Re: Lacrosse 5 disappeared instead of flared at 21:51 UTC

From: Bram Dorreman (bram.dorreman@gmail.com)
Date: Tue Aug 01 2006 - 13:35:16 EDT

  • Next message: Gerhard HOLTKAMP: "Re: Lacrosse 5 disappeared instead of flared at 21:51 UTC"

    Marco Langbroek wrote as reaction to:
    
    2006/7/31, Marco Langbroek <marco.langbroek@wanadoo.nl>:
    > > Also if the YVV/33 degree theory is correct Marco has a chance to observe flares in the next few days
    > >
    > > Flare Results for Observer Lat=52.15412 Long=4.49081
    > > Satellite NORAD 28646
    > > Flare Results for Flight Mode YVV Panel Angle 33°
    > > 12. SAR MA 2.97104043228698 at 31/07/2006 21:51:22 Alt=74.2391395227923
    >
    > Phil a.o.,
    >
    > It did not flare, but disappeared again instead....
    >
    > I picked Lacrosse 5 (05-016A) up at about 21:50:00 UTC near Bootes/CrB. It was
    > mag. +2.5 brightening to +2.0 in the next half minute or so.
    >
    > Somewhere around 21:50:45 I started to look at my clock to trigger the camera
    > countdown at 21:51:07 UTC. When I looked up again at 21:51:09 or so, it already
    > was gone. It did not re-appear.
    >
    > The photograph (21:51:18.1 to 21:51:28.8 UTC) shows no trail at all, meaning
    > that at that time it must have been fainter than +3.5. Would it have been as
    > bright as it was a 21:50:00 to 21:50:45 it would be visible on the image, and
    > certainly if it subsequently would have flared.
    >
    > There was some thin cirrus in the sky, but the area where it should have flared
    > was clear and faint stars are visible on the image.
    >
    > - Marco
    >
    Triggered by the very interesting conversation about the Lacrosse 5
    disappearance trick I follwed this very satellite from my location. I
    timed when L5 disapperead. It was at UT 21:50:56.4 (with about 0.5 sec
    accuracy) from my location at
    COSPAR 4160
    51° 16' 45.5" N 5° 28' 36.6" E (WGS84) 35 m
    
    If these timings are of any interest to other people, I am willing to
    report them via this list.
    
    I replayed L5's track across the sky using Guide 8 to find its azimuth
    and Sun's azimuth. These values are 294° and 332° repectively.
    My L5 brightness estimate was +2.8 when it passed Izar (eps Boo).
    
    Bram Dorreman
    
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