ELEGANT!

Via Eurekalert, an absolutely brilliant measuring technique for a long-established measuring tool. Balloons have been gathering info about weather conditions and radiation from the sun and stars for 120 years. These Japanese researchers used the old tool plus several fiendishly clever tricks:

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Based on the high sensitivity of these films and a novel, automated, high-speed process of extracting data from them, the physicists’ idea was to stack up a few of them to accurately capture the trajectory of the particles that the gamma ray produces on impact, just like a single pancake may capture where you poke a straw into it, but it takes a whole stack to record the straw’s direction.

To reduce atmospheric interference, they then mounted the stack of films onto a scientific observation balloon to lift it to a height between 35 and 40 kilometers.

However, since a balloon is swaying and twisting in the wind, the direction of the “telescope” is not stable, so they added a set of cameras to record the gondola’s orientation relative to the stars at any time.

But this created another issue, because as anybody who has ever taken a photograph with long exposure knows, photographic film does not record the passage of time and so it is not directly possible to know at what time any given gamma ray impact occurred.

To overcome this problem, they made the bottom three layers of film move back and forth at regular but different speeds, just like the hands of a clock. From the relative dislocation of the traces in those lower plates they could then calculate the precise time of the impact and thus correlate it with the cameras’ footage.

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Every element of this tool is OLD. Balloons have been practical for 300 years; photo film for 170; portable video cameras for location are only 80 years old, but synchronized film cameras could done the same job 120 years ago. Assembling the old elements could have been done in 1900, but nobody was creative enough until right now!