Great article, I've always been impressed by this too. It's neat that it sounds like even amateurs with nothing but a regular DSLR can contribute to this as well.
> By precisely timing the duration of the occultation from many sites simultaneously, they can refine their knowledge of the size and shape of the asteroid.
> Betelgeuse is the 10th brightest star in our skies (+0.5 magnitude), so observers need only modest equipment to participate.
> the easiest way to capture the event is to use a simple DSLR camera on a tripod ... video frames must have a short (few-millisecond) exposure time ... Millisecond accuracy timing is crucial ... [an app] for timestamping occultation observations is called Occult Flash Tag (Android) or AstroFlashTimer (iPhone)