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[–] Owlchemy [S] 0 points 1 point (+1|-0) ago 

Same way they do it now.

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[–] Rellik88 0 points 1 point (+1|-0) ago  (edited ago)

So your telling me we had the know how and the precise tools need to do it in 1890?

Edit: Well I guess so,

http://www.astronomy.ohio-state.edu/~pogge/Ast162/Unit1/bright.html

Flux Photometry Count the photons received from a star using a light-sensitive detector: Photographic Plates (old-school: 1880s to 1960s) Photoelectric Photometer (photomultiplier tube: 1930s to 1990s) Solid State Detector (e.g., photodiodes or CCDs) We now use solid-state detectors like CCDs and similar technologies (with very rare exceptions), as these detectors are far more sensitive and stable than any previous technology. Calibrate the detector by observing a set of "Standard Stars" of known brightness.

I'm just curious how can we tell the data taken from the 1890's using photographic plates is accurate. How do we know the star was brighter back then if our measurements with todays tech shows it dimmer?

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[–] MyDrunkAccount 0 points 1 point (+1|-0) ago 

As an answer to your last question, you can just run both tests (plates and new tech) simultaneously on multiple stars and then calibrate and extrapolate.

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[–] Owlchemy [S] 0 points 1 point (+1|-0) ago 

I didn't write the article ... sorry. But I've seen calculations of magnitude going back into ancient times. I guess it's more a matter of do you trust the calculations, and having no further info myself, I can't say.