Lacrosse 5 has a habit of mysteriously fading during a pass. Here are 2
example light curves.
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On 26/03/2007 Mike Tyrrell and I jointly
observed a really interesting pass of Lacrosse 5. Mike managed to resolve
the satellite in various images which will soon be processed. During the
pass Lacrosse 5 performed all its brightness tricks. At the beginning
there was a double flare. Clearly we did not observe that event
simultaneously. The ground track of the flare was sweeping from West to
East which meant I saw it at 20:04:20, 5 seconds after Mike.
This flare is consistent with flight mode YVV and a panel angle of
32.4° (although I now think a curved panel is most likely).
At 20:04:54 a sudden 3 magnitude fade occurs. This event was observed
simultaneously by Mike and me and also Gerhard Holtkamp in Germany. This
proves the fade is inherent to the satellite and not a function of viewing
angle.
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Another sudden fade after a corresponding
brightening. This was very similar to 19/03/07 when the satellite flared
slightly before eclipse but seemingly entered eclipse rather early so
maybe it had actually started to fade.
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A half magnitude fade of Lacrosse 3. Much
smaller than Lacrosse 5 but proves a fade event is not unique to L5.
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Here Lacrosse 5 faded by about 2.5 magnitudes
in 14 seconds.
The y-scale is inverted so that bright magnitudes are at the top making
it more intuitive to view.
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A sudden brightening, then a drop of 5
magnitudes then a final flare. A tough light curve to explain!
This data is from an observation by Mike Tyrrell. I have a video of the
event but I bungled the software so I have no brightness curve.
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