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Is the difference between this and a normal telescope that it has a wider field of view for the same level of detail? So you could do the same thing more slowly

Is the difference between this and a normal telescope that it has a wider field of view for the same level of detail? So you could do the same thing more slowly by taking hundreds of pictures in different directions with a normal telescope?

coldbrewed 3y ago
Correct, the camera is built for an all sky survey. With the wide field of view it should be able to image the full night sky once every two or three days.
- mturmon 3y ago
  Yes, and to amplify, part of the utility is in its ability to observe transient phenomena. As we have been able to do more large-scale surveys, and scan the resulting images with transient detection software, we have observed a lot of surprises. LSST is designed to step that up by a lot. See: https://en.wikipedia.org/wiki/Time-domain_astronomy https://en.wikipedia.org/wiki/Time-domain_astronomy
aragilar 3y ago
It depends what you mean by a "normal telescope" (all telescopes used for astronomy are designed for specific tasks/roles, even if that's not called out in public-facing material as much). LSST is not the first large scale optical survey (and previous telescopes have chosen to have a wide field of view, but they've been quite small in comparison), and there are tradeoffs to trying to use such a large field of view (e.g. having to correct for lots of distortions, both in the design of the optics, and in software), but because of the large collecting area (being a 8-meter class telescope), you can go much fainter faster (and with higher signal to noise) than a 1-meter class telescope that has the same field of view. Wikipedia has a bit about what makes LSST special (https://en.wikipedia.org/wiki/Vera_C._Rubin_Observatory#Comparison_with_other_sky_surveys https://en.wikipedia.org/wiki/Vera_C._Rubin_Observatory#Comp...). I don't know when they're going to start observations, but I suspect there'll be loads of announcements of cool new transients soon after.
mnw21cam 3y ago
The other difference is partly a consequence of the wide field of view. That thing has a huge front lens, which lets in a massive amount of light, so the brightness of the projected image on the sensor is much higher than a telescope that has a zoomed-in field of view. That means it is able to use a relatively short exposure and still see things in the sky that are fairly dim. To use numbers to compare to any other camera, it has a 3.2 gigapixel sensor with a diameter of 640mm, and the "lens" (actually several mirrors) has a focal length of about 10m and a diameter of about 8m, giving it an f-ratio of f/1.2, which is very impressive (although the central part of the "lens" is obstructed, giving it a light-collecting ability more like an f/1.5 lens).
- ianburrell 3y ago
  The Rubin telescope, like all larger telescopes, doesn't have a lens. It has a 27ft main mirror. I think the big difference is the size of secondary mirror which is 11ft in diameter. It can be compared to the neighboring Gemini South telescope which is similar size but has 3ft secondary and f16 focal length.

coldbrewed 3y ago

Correct, the camera is built for an all sky survey. With the wide field of view it should be able to image the full night sky once every two or three days.

mturmon 3y ago
Yes, and to amplify, part of the utility is in its ability to observe transient phenomena. As we have been able to do more large-scale surveys, and scan the resulting images with transient detection software, we have observed a lot of surprises. LSST is designed to step that up by a lot. See: https://en.wikipedia.org/wiki/Time-domain_astronomy https://en.wikipedia.org/wiki/Time-domain_astronomy

aragilar 3y ago

It depends what you mean by a "normal telescope" (all telescopes used for astronomy are designed for specific tasks/roles, even if that's not called out in public-facing material as much). LSST is not the first large scale optical survey (and previous telescopes have chosen to have a wide field of view, but they've been quite small in comparison), and there are tradeoffs to trying to use such a large field of view (e.g. having to correct for lots of distortions, both in the design of the optics, and in software), but because of the large collecting area (being a 8-meter class telescope), you can go much fainter faster (and with higher signal to noise) than a 1-meter class telescope that has the same field of view. Wikipedia has a bit about what makes LSST special (https://en.wikipedia.org/wiki/Vera_C._Rubin_Observatory#Comparison_with_other_sky_surveys https://en.wikipedia.org/wiki/Vera_C._Rubin_Observatory#Comp...). I don't know when they're going to start observations, but I suspect there'll be loads of announcements of cool new transients soon after.

mnw21cam 3y ago

The other difference is partly a consequence of the wide field of view. That thing has a huge front lens, which lets in a massive amount of light, so the brightness of the projected image on the sensor is much higher than a telescope that has a zoomed-in field of view. That means it is able to use a relatively short exposure and still see things in the sky that are fairly dim. To use numbers to compare to any other camera, it has a 3.2 gigapixel sensor with a diameter of 640mm, and the "lens" (actually several mirrors) has a focal length of about 10m and a diameter of about 8m, giving it an f-ratio of f/1.2, which is very impressive (although the central part of the "lens" is obstructed, giving it a light-collecting ability more like an f/1.5 lens).

ianburrell 3y ago
The Rubin telescope, like all larger telescopes, doesn't have a lens. It has a 27ft main mirror. I think the big difference is the size of secondary mirror which is 11ft in diameter. It can be compared to the neighboring Gemini South telescope which is similar size but has 3ft secondary and f16 focal length.