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by hajola 505 days ago
Figuring out the optimal placement of CCDs on Plato's 24(+2) cameras. Due to the way CCDs are fabricated, their properties vary a bit, they are not identical. For example, they can vary how much light they can hold before they become saturated. Given the high cost of fabricating these CCDs, and the fact that for each camera 4 CCDs are used, and all these 4 have to share front-end electronics, it was prudent to optimize their grouping to we maximise the dynamic range we get. More dynamic range means that we can tell more about the planets we find with higher confidence.
2 comments
ziddoap 505 days ago
>CCDs

I think this is "Charge-Coupled Device"?

"an electronic sensor that converts light to digital signals through charges generated by bouncing photons on a thin silicon wafer"

Is that correct? Not familiar with the acronym.

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UltraSane 505 days ago
Yes. In telescopes they use high-end CCDs with really big pixels for better light sensitivity and zero dead pixels.

This is a picture of the CCD array for the Gaia space observatory that used parallax to measure precise distances and slightly less precise angular velocities of billions of objects

http://www.bo.astro.it/~altavilla/FTP/GAIA/IMAGES/The%20comp...

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hajola 505 days ago
Yes that's correct.
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fragmede 505 days ago
That's awesome! Are the multiple CCDs because you're taking photos in separate colors or something?
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hajola 505 days ago
Good question. No, these will essentially be black-white "photos". The amount of light is measured. The reason for so many CCDs is so that the field of view would be as large as possible. A larger field of view enables to look at more stars at once. Given that we will be locked into looking at one spot for a whole year, it ups our chances of spotting something cool if we maximise the number of stars we are looking at.

However they won't be photos of planets really. It will be countless photos of the same stars over and over again, it's just that sometimes they will be slightly less bright than other times. Directly imaging exoplanets is incredibly difficult, but humans have managed it: https://en.wikipedia.org/wiki/List_of_directly_imaged_exopla...

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