My God, it's full of stars
Image creator here. Now imagine, when the survey is done, we will be able to see even fainter objects and image an area of the sky 1000x times this size.
Vera C. Rubin Observatory first images
131–140 of 172 posts
Re: Vera C. Rubin Observatory first images
#132The zoomed images look grainy as one would expect from raw data, but I would have expected them to do dark field subtraction for the chips to minimize this effect. Does anyone know if that's done (or expressly avoided) in this context, or why it might not be as helpful (e.g., for longer exposures)?
Image creator here. We do dark field subtraction, as well as many other instrumental calibrations. What you are seeing is the fundamental photon noise. Because it is statistical in nature, you can never completely eliminate it. We could have chosen to put the black point in the image at a much higher flux level, but if you go to a high enough signal to noise level that you see no grain anywhere, you would miss out on so many interesting things that are still quite obvious to make out but are only 2-3 sigma above the noise.
Re: Vera C. Rubin Observatory first images
#133I'm the Rubin team member responsible for mapping the data into RGB images. I have been a long time reader of hacker news, but finally made an account to comment on this. I wanted to thank everyone here for their interest and taking their time to check out these images. Seeing everyone interested and engaged makes all the long hours worth it.
What range of wavelengths are in the original images? Do you produce multiple RGB images for looking at different things? c'mon, what does that entail? ;-)
The filters used for this range from near infrared to near uv. We used 4 different filters in all (for this image, the telescope has more). In general yes to fully appreciate all the color information as a human we need to generate different color combos so our eyes can pick up different contrasts.
However, what we strive for is being accurate to "if your eyes COULD see like this, it would look like this". To the best our our ability of course. We did a lot of research into human perception to create this and tired to map the information of color and intensity in a similar way to how your brain constructs that information into an image.
Let me tell you, I did not appreciate how deep a topic this was before starting, and how limited our file formats and electronic reproduction capabilities are for this. The data has such a range of information (in color and intensity) it is hard to encode into existing formats that most people are able to display. I really want to spend some time to do this in modern HDR (true HDR, not tone-mapping) where the brightness can actually be encoded separately than just RGB values. The documentation on these (several competing) formats is a bit all over the place though.
Edit: I wanted to edit to add, if anyone reading this is an expert in HDR formats and or processing, I'd live to pick your brain a bit!
Re: Vera C. Rubin Observatory first images
#134Why do the brighter objects have the four way cross artifact? My (apparently incorrect) understanding was that those types of artifacts were a result of support structures holding reflecting mirrors on a telescope. But this camera just has a "standard" glass lense with nothing obstructing the light path to the sensor.
You are not wholly wrong! There is both a supporting structure for the mirror, AND a glass lens in front of the sensor to further flatten the incoming light.
The interesting thing about the spikes in our images is that they stay fixed in image plane coordinates, not sky coordinates. So as the night sky moves (earth rotates) the spikes rotate relative to the sky leading to a star burst pattern over multiple exposures.
Re: Vera C. Rubin Observatory first images
#135Every set of deep field imagery reminds me that any point of light we see could be a star, a galaxy, or a cluster of galaxies. The universe is unimaginably vast. For observatories like Rubin, is there a plan for keeping them open after the funding ends? Is it feasible for Chile to take over the project and keep it going? On a practical note, what happens to a facility like this if one day it's just locked up? Will it…
It will continue with a new instrument after 10 years (spectroscopic) funding permitting. Tololo has been running since the 60s. In California, Lick has been running since the 1880s.
I get that it will run for a long time as long as someone is maintaining it. I am wondering what will happen if the doors are locked and the power is cut for an extended period of time (5+ years), as seems like a very real possibility unless an alternate source of funding can be found.
Re: Vera C. Rubin Observatory first images
#136Earlier quoted context omitted.
If it has the potential to wipe out our entire species, but there's something we could do to prevent it (which I'm not sure about w/r/to asteroids), then it's worth looking out for the black swan event. Doing some extremely rough math along these lines to double check myself: * Gemini says that a dinosaur-extincting asteroid hits Earth about once every 100 million years. So in any given year that's 0.000001%. * Econo…
It seems incredibly bizarre to assign a monetary value to the elimination of all human life given the concept of monetary value would be wiped out along with the people.
The counterpoint is that not doing so (implying some sort of infinite monetary loss if the entire human species is wiped out) would mean you want to spend every single unit of monetary value of the entire global economy to preventing this (which is also obviously nonsense - people have to eat after all).
So you have to put the monetary value somewhere (although you're completely within your right to question this specific amount).
Re: Vera C. Rubin Observatory first images
#137Every set of deep field imagery reminds me that any point of light we see could be a star, a galaxy, or a cluster of galaxies. The universe is unimaginably vast. For observatories like Rubin, is there a plan for keeping them open after the funding ends? Is it feasible for Chile to take over the project and keep it going? On a practical note, what happens to a facility like this if one day it's just locked up? Will it…
There are already facilities like this (obviously not as new as Rubin) degrading due to funding, but this is because there's usually no better purpose for them. Space monitoring has been used in the past as a second life for facilities (outreach too), but ~1m class telescopes are good enough now that networks of them are better than a 40+ year old telescope. It's also worth noting bits can be reused: buildings gutted…
I just skimmed the budget request, and it looks like NSF is planning on keeping Vera C. Rubin at least through 2026. Really good news!
Re: Vera C. Rubin Observatory first images
#138Earlier quoted context omitted.
It seems incredibly bizarre to assign a monetary value to the elimination of all human life given the concept of monetary value would be wiped out along with the people.
The counterpoint is that not doing so (implying some sort of infinite monetary loss if the entire human species is wiped out) would mean you want to spend every single unit of monetary value of the entire global economy to preventing this (which is also obviously nonsense - people have to eat after all). So you have to put the monetary value somewhere (although you're completely within your right to question this spe…
That's the most interesting application of capitalism-as-as-resource-allocation mechanism I've ever seen, that's something I look forward to thinking about more.
My immediate reaction though is to doubt the mapping of dollar to value - e.g., the 10 million dollar valuation of the human life, but also the valuation then of all the things that year-dollar-cost could be spent on. Many of those things probably don't map very well between true value, and dollar cost (my go-to example of this is teachers fulfilling one of the most critical roles to ensure a functioning society, yet the dollar cost paid for their labor being typically far lower than most other jobs).
Re: Vera C. Rubin Observatory first images
#139I really like the Rubin because I think a lot of people focus too much on "deep" seeing (IE, looking at individual or several objects with very high magnification only once). The Rubin does much more "wide" seeing and this actually produces a ton of useful data- basically, enough data to collect reliable statistics about things. This helps refine cosmological models in ways that smaller individual observations cannot…
You worked on the design? That is interesting. I worked on the simulating the LSST , back in 2008 to 2010. The goal of which was to test the data reduction software. We were on the Image Simulation team. It is surreal to see LSST/Rubin finally get first light. Even more interesting to see who is still working on LSST, and who is not.
We also simulated the LSST- in this case, using Exacycle at google (an idle cycle harvester). We took a star catalog and passed it through a highly accurate ray tracer that simulated the light falling on the sensors (through space, atmosphere, etc). Apparently it found some bug in the design that was fixed before some expensive part was built (my coworkers were the subject matter expert, I mainly built the exacycle software and sat in on the meetings).
Re: Vera C. Rubin Observatory first images
#140Earlier quoted context omitted.
https://en.wikipedia.org/wiki/Olbers%27s_paradox
Note that it makes a lot of assumptions beyond the stated ones, such as: * the only objects in space are stars * all stars are equally bright * the average brightness is one that can be seen (unless you roll all this into "homogeneous"?)
Yeah I'm confused because couldn't a black hole between us and a star be the reason for a black spot? That times a bajillion for whatever else is out there.