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

From: Philip Masding (
Date: Fri Aug 04 2006 - 16:38:01 EDT

  • Next message: Kevin Fetter: "Hotbird 8 launched"

    I have made a table of all observed flares and disappearences for Lacrosse 
    satellites that I know about.
    I have just added Gerhard's observation. A flare was predicted for his site 
    for 20:56:50 and is consistent with the L5 panel being at around 33° which I 
    worked out from observations by Marco Langbroek and me.
    Disappearences are harder to explain but maybe have something to do with the 
    altitude of the Sun relative to the satellite. In fact I can't think what 
    else it could be unless L5 really does have Star Trek cloaking technology. A 
    rough analogy would be when would aeroplane wings cast a shadow on the tail 
    plane? Answer whenever the Sun shines along the fuselage which I would say 
    is 0° in its local co-ordinates.
    ----- Original Message ----- 
    From: "Gerhard HOLTKAMP" <>
    To: <>
    Sent: Tuesday, August 01, 2006 10:29 PM
    Subject: Re: Lacrosse 5 disappeared instead of flared at 21:51 UTC
    Bram Dorreman wrote as a reaction to Marco Langbroek:
    >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
    I've observed that L5 pass with a 3'' refractor from my location at 49.8866 
    8.6558 E between 21:48:59 UT (31-JUL-06) when it passed Eta Boo and a few
    seconds after it passed Eta UMa at 21:50:56. It steadily increased in
    brightness up to UMa. It seemed to decrease in brightness in the final few
    seconds that I saw it (I lost contact due to some obstruction in my field of
    view). But whether this was due to the disappearance effect or due to the
    obstructions (and some clouds) getting in my way I  cannot re-construct.
    Half an hour ago (at 20:56:35, 1-AUG-06) I observed what looked like the
    beginning of a flare of L5 (which passed from Arctures to UMa) but once 
    clouds got into my way.
    Gerhard HOLTKAMP
    Darmstadt, Germany
    Subscribe/Unsubscribe info, Frequently Asked Questions, SeeSat-L archive:
    Subscribe/Unsubscribe info, Frequently Asked Questions, SeeSat-L archive:

    This archive was generated by hypermail 2b29 : Fri Aug 04 2006 - 16:39:49 EDT