Near-Earth Asteroid 2014 SC324: an exceptional movie
Last night, at Virtual Telescope we tracked the near-Earth Asteroid 2014 SC324, sharing it with our followers online, in real time.
In particular, on 25 Oct. 2014, we managed to collect 110 images, back to back, covering the 00:12 to 00:42 UT (30 minutes). This ~60 meters large asteroid showed evident variations in brightness suggesting it was a quite elongated body. A first guess suggests an amplitude of 1.5 magnitudes.
The animation above alternates the max and minimum brightness, showing the full amplitude at a glance. Images were carefully adjusted so that the variation you see is just real.
Understanding that variation is easy: the asteroid is rotating and, because of a very elongated shape, it is changing during rotation the amount of light it is reflecting to us. The larger the amplitude, the stronger the elongation (in principle, darker/brighter areas on the asteroid could do the same, independently from the shape). Things can be of course much complicated (as for non-principal axis rotators), but that is the key point.
Of course, the apparent luminosity changes smoothly if you consider a continuous coverage and it can be better seen in the video below, showing all the available 110 frames. NB: a larger (16Mb) version is available here. We are working to extract useful data from these observations.
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