The future heart of the Vera C. Rubin Observatory will soon make its way to Chile:
The world's largest camera sits within a nondescript industrial building in the hills above San Francisco Bay.
If all goes well, this camera will one day fit into the heart of the future Vera C. Rubin Observatory in Chile. For the last seven years, engineers have been crafting the camera in a clean room at the SLAC National Accelerator Laboratory in Menlo Park, Calif. In May 2023, if all goes according to plan, the camera will finally fly to its destination, itself currently under construction in the desert highlands of northern Chile.
[...] "We're at the stage where we've got all the camera's mechanisms fully assembled," says Hannah Pollek, a staff engineer at SLAC.
Any typical camera needs a lens, and this camera is certainly no exception. At 1.57 meters (5 feet) across, this lens is the world's largest, as recognized by the Guinness Book of World Records. When it's installed, it will catch light reflected through a triplet of mirrors, built separately.
In action, the telescope will point at a parcel of sky, 3.5 degrees across—in other words, seven times the width of the full moon. The camera will take two exposures, back-to-back, approximately 15 seconds each—bracketed by the sweeping of a colossal shutter. Then, the telescope will move along to the next parcel, and so forth, in a mission to survey the southern sky for years on end.
Behind the lens sit the detectors, which are fashioned from charge-coupled device (CCD) sensors, common in astronomy. With the lens cap removed, the detectors are visible as a silver-and-blue grid, the different colors being a consequence of the camera having two different suppliers. Together, they can construct images that are as large as 3.2 gigapixels.
[...] If all goes well with the last phase of construction, this camera will soon depart California for Chile and catch its first glimpse of the night sky by 2024.
(Score: 4, Informative) by ChrisMaple on Thursday October 06 2022, @03:33PM (2 children)
The sensor is 1.57 meters across, not the lens.
(Score: 2) by RamiK on Thursday October 06 2022, @03:41PM
thanks exactly what I was wondering about.
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(Score: 0) by Anonymous Coward on Thursday October 06 2022, @05:46PM
The sensor is 64 cm [lsst.org] across. The lens is about 1.65 meters [lsst.org] in diameter, if you take the outer diameter that includes the lens tube.
(Score: 2) by RamiK on Thursday October 06 2022, @03:37PM (1 child)
The lens on the Gran Telescopio Canarias is 10.4 m: https://en.wikipedia.org/wiki/Gran_Telescopio_Canarias [wikipedia.org]
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(Score: 2) by StupendousMan on Thursday October 06 2022, @04:47PM
The GTC uses mirrors to focus light, not a lens.
(Score: 2) by JoeMerchant on Thursday October 06 2022, @09:00PM (1 child)
So, they built a massive telescope with a specific imaging algorithm in mind which is highly susceptible to interference - not only from passing satellites - but also anything at all that may meander across its field of view during one of the two exposures.
If they would have gone for three exposures they could have used a simple best 2/3 comparison to determine the most accurate luminance value in each pixel of the final image.
🌻🌻 [google.com]
(Score: 2, Interesting) by Anonymous Coward on Friday October 07 2022, @02:06AM
I think one of the things this camera is for is to actually look for those transients. They are looking for asteroids and comets too.
(Score: 2) by turgid on Sunday October 09 2022, @09:49AM
Why does it need a shutter if it uses CCDs to capture the image?
I refuse to engage in a battle of wits with an unarmed opponent [wikipedia.org].