# Re: Late night - 28237 or MDS 1 x3 flashes ~ 25 second

From: Björn Gimle (bg_26934@glocalnet.net)
Date: Wed Dec 21 2005 - 14:24:12 EST

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```Cylindrical objects (like rockets) usually tumble end-over,
ie around an axis perpendicular to the long axis.
That will cause two symmetrically timed flashes per rotation.

In many cases, eg when the axis isn't exactly at right angles,
or when the object is slightly conical, the two flashes
occur slightly asymetrically in time,and the
double period becomes very obvious.

If the object has other symmetry, and/or more reflecting surfaces,
analysis of flash timing and brightnesses of flashes can reveal
the true period.

I do many such analyses using my program SYNODIC.
The name implies that since observer-satellite-Sun angle varies
during an observation, the start and end flash do NOT mark
an integer number of rotation periods (or even half periods).
With a complex geometry, different surfaces can have slightly
different periods, and they can vary during the pass, since
the satellite apparent speed varies.

Essentially, SYNODIC presents a graph of absolute
times (cumulative laps) MODULO assumed period.
This can easily be done with Excel or other programs.

Varying the period leads to (nearly) horizontal bands
of flash times, and then trying integer multiples or
fractions can reveal fine asymmetries and synodic
variation, and the "true" period.

/Björn

----- Original Message -----
From: "ykchia"
> ...
> What is the reason   reported timing which is x2 ( double) the
> fundamental timing.. and in this case x3 ( x3x8=24)... in general

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