Why was it important to measure the positions of the stars and write them all down?
Surely just keeping the plate is sufficient information... If you ever need to see what a star looked like, you can still look back at the plate. And plates could also be reproduced in books and papers.
I suppose it was easier to share books with tables of positions than photographic plates. Easier to copy as well, and it does not degrade quite as much with time.
If so, there’s not much more to see on these plates than position and brightness (I assume these were black and white plates, as color photography still was fairly experimental in 1870)
Also they didn’t make the map to look at individual stars (they wouldn’t use “pictures of an enormous 3x2 degrees of the sky” for that), but to answer questions such as whether the distribution of stars is uniform or whether stars move relatively to each other in the sky. For both, you need positions.
That's a different project. The podcast episode concerns Pickering and his group at the Harvard College Observatory, in the US.
This operation was the Carte du Ciel. As the article says:
> Although Pickering from Harvard was at the meeting, no American observatory chose to participate in the survey. The Americans thought a shallower, faster survey might be good enough, rather than the monumental work proposed in Paris, and they were suspicious of large, centrally organized projects.
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[ 2.9 ms ] story [ 26.1 ms ] threadSurely just keeping the plate is sufficient information... If you ever need to see what a star looked like, you can still look back at the plate. And plates could also be reproduced in books and papers.
If so, there’s not much more to see on these plates than position and brightness (I assume these were black and white plates, as color photography still was fairly experimental in 1870)
Also they didn’t make the map to look at individual stars (they wouldn’t use “pictures of an enormous 3x2 degrees of the sky” for that), but to answer questions such as whether the distribution of stars is uniform or whether stars move relatively to each other in the sky. For both, you need positions.
https://thememorypalace.us/400000-stars/
This operation was the Carte du Ciel. As the article says:
> Although Pickering from Harvard was at the meeting, no American observatory chose to participate in the survey. The Americans thought a shallower, faster survey might be good enough, rather than the monumental work proposed in Paris, and they were suspicious of large, centrally organized projects.