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 ------------------------------------------------------------------------- Subscribe/Unsubscribe info, Frequently Asked Questions, SeeSat-L archive: http://www.satobs.org/seesat/seesatindex.html
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