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原始链接: https://news.ycombinator.com/item?id=40010221

本文讨论了两质量项目进行的微米全天巡天。它涉及对高红移双类星体的观测，特别是在为期六个月的调查期间。类星体是位于星系中心的超大质量黑洞。通过引力透镜，研究人员旨在收集有关遥远的早期类星体的信息。虽然提供的文本提到了当前观测的细节，例如其持续时间和目标，但值得注意的是，显示的不是实时图像，而是望远镜指向的指示。无论其外观如何，包括红色和绿色的“斑驳图案”，这些都可能是由于滤镜图像内的噪声或自然现象（例如红移物体）造成的。此外，作者表达了对浩瀚太空和我们在其中的地位的迷恋。他们建议考虑可观测宇宙的巨大性，其中包含多达 2 万亿个星系和潜在的 10^24 颗恒星，这突显了人类在掌握如此大的数字时面临的困难。尽管提供了有趣的信息，但获取詹姆斯·韦伯太空望远镜 (JWST) 所关注区域的实际表示似乎具有挑战性。据推测，显示的数据来自预先存在的图像或模拟，而不是实时反馈。太空探索的历史涵盖了卫星技术和潜在军事应用的重大发展，包括在地球轨道上部署车间和工具等先进能力。

I’m getting the impression that some people don’t know what they’re looking at. It says “Background: Two Micron All Sky Survey” which you can read about here [1]. This is not a live image. It’s just showing you where it’s pointing, which isn’t so meaningful for most of us. (It’s random-looking stars.)

You can read interesting details about the current observation at the top, though. Currently:

* A census of high-redshift kpc-scale dual quasars

* A 49 minute, 55 second observation.

There’s a link to the research proposal [2]

Apparently it’s a six-month survey of dual (possibly lensed) quasars. Gravitational lensing can cause magnification, distortion, and duplication of the image of whatever is behind it, so this is a way to learn more about very distant (early) quasars.

A quasar is a supermassive black hole at the center of a galaxy, so this seems like a way to take lensed pictures of a lot of early galaxies?

[1] https://en.m.wikipedia.org/wiki/2MASS [2] https://www.stsci.edu/jwst/science-execution/program-informa...

Webb won't ever provide a recent view since the images belong to the research group and are only made public when the results are released.

Also, Webb can't provide a video feed since it is taking long exposures, and probably only sends results back to Earth when image is finished. The images are in the infrared and only look good when processed.

To expand on this, Webb uses the Deep Space Network (DSN) to communicate with us. It can’t stream data back 24/7. There are generally three contacts per day each lasting a few hours, but I believe this is dependent on the scheduling of contacts with other missions that also use the DSN.

Also, the science data that is sent back is a stream of packets from all the data that was taken since the last contact. The packets are arranged for efficient transmission. One of the first steps of the science data processing is to sort the packets into exposures. Often packets for an exposure are split among multiple SSR (which stands for solid-state recorder) files. Sometimes there are duplicate packets between SSRs (data sent at the end of a contact is repeated at the beginning of the next contact). Only when the processing code determines that all expected packets are present—by using clues from other subsystems—can the next step (creating the uncalibrated FITS) begin.

If anyone is interested more details, the packet stuff is based on standards from the Consultative Committee for Space Data Standards (https://public.ccsds.org/Publications/BlueBooks.aspx).

> only look good when processed

Ehh. I personally can’t stand all the post processing folks love to make their results look “magazine ready”. I think the most minimal transformation possible to map the data into 0xRRGGBB would look the best, ideally with a simple standardized algorithm that doesn’t allow for any “artistic license”.

Are they not doing that? What is the origin of the idea that they sit on the images too long choosing a custom wavelength conversion formula? Is it just that their images look good?

IR pictures would be not RGB, just black/white (or whatever palette you like). But yes, it would be possible. For ex. from Flir Thermal cameras, you also can output the image just as spreadsheet. You can even choose the values as temperature (which is calculated) or just as energy (what the sensor gets).

Light isn’t RGB. We just receptors that react to certain wavelengths. I suspect the sensors on the telescope have a range of wavelengths they are sensitive to. It would be a straightforward translation to shift it to map it to the visible spectrum without varying the relative intensities to accentuate certain aspects of the image.

The IR may be in a very narrow band. The visible wavelengths have different colors because there are a range of wavelengths that correspond to different cones in our eyes that roughly match red:green:blue sensors. If you shift the IR frequency up into the visible range, you would just get a luminance image (like grayscale) centered on one visible wavelength like red.

False color imaging sometimes applies colors to different luminance levels or sometimes it takes multiple images at different wavelengths and assigns RGB values to each of those wavelengths. The results are informative but require some editorial / aesthetic decisions to produce the best results.

That's not how vision works. You see an extremely post processed image that's extremely far away from the original light that hit your retinas. There's nothing at all privileged about shifting something into the visible spectrum directly and seeing junk. You're just making an image that your visual system isn't good at understanding. It's not pure, it's garbage. You would hallucinate things that aren't there, you would miss obvious things that are there, etc. For you to really comprehend something the transformation needs to be designed.

I encourage you to try some raw file photography and processing. A bitstream from a sensor is not an image and there is no “correct” or “accurate” image from a captured signal.

Think of it like using a linear or log scale for a chart axis: neither is “more correct”, neither is taking “artistic license”.

Poor example, given many photographs shoot raw precisely because it gives them more room for artistic decisions in post. Obviously the standardized algorithm should have basic factors like gamma and general phase shifting incorporated, but the idea of being able to adjust the maps delta between arbitrary adjacent inputs is of questionable benefit to the community. It’s akin to adjusting levels via curves with many points, and it’d be incorrect to say folks are taking artistic liberties when they do that.

Hmmm, unfortunate timing:

"Planned Outage - On Friday, April 12th starting at noon through Sunday, April 14th, Space Telescope Live may be unavailable. We apologize for any inconvenience."

If I zoom in, I see a reddish mottled pattern. Is that sensor noise, background radiation, or something else?

Similarly, if I zoom out to 30.39 angular degrees, there's a similar-ish green mottled pattern that's very prominent. What's that? It looks like it's got linear features, which might be a stitching artefact of some sort, maybe?

> If I zoom in, I see a reddish mottled pattern. Is that sensor noise, background radiation, or something else?

I assume you mean the pattern that is distributed across the general image? That's noise in one of the three filter images used to make the color image. 2MASS imaged in the J, H, and Ks filters (likely mapped to blue, green, and red, respectively). It could be that the choice of stretch is emphasizing the noise in that filter a bit more. Alternately, the noise there could be a bit higher (at the long wavelength end, Ks starts to cover a part of the spectrum where there's appreciable emission from a ~300K blackbody, i.e., the general temperature of things Earth).

> Similarly, if I zoom out to 30.39 angular degrees, there's a similar-ish green mottled pattern that's very prominent. What's that? It looks like it's got linear features, which might be a stitching artefact of some sort, maybe?

Perhaps regions where the image was made using only the H band from the 2MASS survey?

I'm not an astronomer, but I believe the "mottled red" features are distant objects that are redshifted. Note that they're almost all red no matter where you zoom in. That's the evidence that space is expanding in a nutshell.

Distant objects do tend to look redder because of redshift, but the mottled pattern is a bit too regular to all be distant galaxies. It's more likely to be the noise in the data used for the red channel (likely the infrared Ks filter).

+1!! This may sound weird, but I can use this as a mood booster when life gets tough. Side note: I might be biased because I also find it useful to think about the vastness space to trick my brain falling asleep (I watch a lot of video astronomy videos).

“Space is big. You just won't believe how vastly, hugely, mind-bogglingly big it is. I mean, you may think it's a long way down the road to the chemist's, but that's just peanuts to space.”

Per wikipedia:

The observable universe contains as many as an estimated 2 trillion galaxies and, overall, as many as an estimated 10^24 stars – more stars (and earth-like planets) than all the grains of beach sand on planet Earth. The estimated total number of stars in an inflationary universe (observed and unobserved) is 10^100.

IMO, a trillion is a number the human mind has trouble conceiving. We understand it only in an abstract sense - if you try to imagine what a trillion stars looks like in front of you, or a billion, or a million even, most likely you're imagining at best tens of thousands. 10^24 is orders of magnitude more abstract:

1,000,000,000,000,000,000,000,000

I have always found the analogy all the grains of sand on the beaches of earth to be something that helps accurately convey large numbers to myself and others. Somethings I’ve always wondered about this analogy:

1 – at what depth are they referring to, i.e. if you’re at a beach and dig down two feet you’re still Coming in contact with sand (and grains of sand). Do these count also?

2 – if you wade out into the ocean and go underwater, there are also more grains of sand under the water (are these included?). (what about all the grains of sand on the various vast deserts around earth?)

For number two I would assume NO as the analogy says all the grains of sand on the earths beaches a beach.

Forget the universe, just consider the size of the Milky Way. If the Milky Way was shrunk down to the size of United States, the Earth would be smaller than the gap between the ridges in a fingerprint.

Quite fun. I was thinking it would be awesome to have whatever Webb is currently looking at as my desktop background or a website background or something. Glancing through the FF inspector it doesn't look like there is a single image which represents that, though. It looks like a piece of JS called Aladin is stitching together a bunch of 512x512 images. Anybody know more about this?

Not sure about JWST, but for Earth-observing satellite data it's common to store data in formats that support tiling and ranged reads so that clients are only loading the parts of the dataset relevant to current view.

My guess is something similar is happening here on the other side of that library.

I think most operating systems let you set a web page as your wallpaper... or they used to, at least.

Not sure if there's a way to make this site load full screen by default though. And I don't know if the "desktop browser" can run user-scripts...

The other option is to use Chrome/Firefox headless mode and take a screen shot.

You can probably then crop it automagically with some command line image tool to get you an image for your desktop.

I presume it's not a live view of what Webb is seeing but existing images / visualisations from other sources pointing in the same direction Webb is right now.

This is so very, very cool.

I did hear some horrible news. Seems the funding for the next-gen (or even current maintainence of) Chandra-X ray observatory (space based telescope) won't get approved which is a huge shame.

Maybe politicians could be persuaded by sites like these and greater awareness campaigns to not lose such a worthwhile instrument for science.

And if it does is there an international equivalent maybe via the ESA or another that could make up for it or should the science world suffer because of the lack of US funding?

The politicians aren't going to be persuaded by this, they're corrupt snakes who are very open with their lack of regard for actually useful programs.

Chandra et al are dying because Congress wants to pour more money into SLS (and thus into Boeing), but is unhappy that NASA isn't playing along (choosing SpaceX and a similar lander from Blue Origin, buying high risk, lower cost robotic landers from space startups). So they give NASA more money than they ask for when it comes to SLS, dont allocate enough to other Artemis goals and cut the overall budget.

But once the space race to the moon was won - and all major powers had proven they are capable of producing ICBMs - it feels like the energy and financing just went out of it. There's no more political or military gain to be had from space exploration so governments only put in a token amount, and there's only limited commercial gain from e.g. telecom, mapping and navigation, but that's all focused on earth itself.

There's no major financial incentive go to the moon or mars, other than would-be space tourists or colonists that are willing and able to pay for their own trip.

The only way spacefaring could be commercialised is with asteroid mining, and that's a long way away still. The eye-popping "this asteroid could be worth a hundred trillian dollars!!1" kind of headlines are sensationalised to attract investors to fund exploration missions to figure out if the theory matches the practice, but even if it was worth that amount, getting any material back to Earth is currently cost- and engineering-prohibitive. It may become viable in our lifetime, for example if they can get a Starship sized craft there, fill the hold with titanium and return all of it to Earth, but that's a long way away still.

It didn't end just at the ICBM of course or even the nuclear submarine. Satellite warfare became and is still a huge focus. Of course the public was pitched the maintenance bay of the space shuttle was to repair a peaceful satellite only. However, you can imagine how supremely useful it would be for a modern military to have the capability of deploying sappers and a workshop on any object in earth's orbit as well, which is what the space shuttle system also allowed for.

> But once the space race to the moon was won - and all major powers had proven they are capable of producing ICBMs - it feels like the energy and financing just went out of it.

Quite a few things have been done since then, including the JWST, all the other space telescopes, helicopters on Mars, visits to every planet in our solar system system, ...

> There's no major financial incentive go to the moon or mars, other than would-be space tourists or colonists that are willing and able to pay for their own trip.

I don't think there's any incentive at all. What reason is there for anyone to go to Mars other than to say they did, at enormous expense and technical effort? Best case scenario, after spending tens of trillions of dollars, we're able to build a base that needs continual resupply from Earth and in which you're basically living in a box - you'll never be able to set foot outside except in a suit, worse even than our Antarctic bases. And even then, we can expect long-term health effects. Well, you can live in a box on Earth.

The reason there isn't major funding for space is because most people don't care all that much. It's a nice thing to have, and I wish more people did support increasing this sort of funding, but it's perfectly understandable why most people don't want to contribute significant percentages of GDP to a scifi dream.

We're not talking about a vanity Mars visit, we're talking about building an X-ray observatory. The JWST has already been phenomenal, it feels like it's delivering an almost daily barrage of discoveries, many of which are already affecting long standing understandings of the universe. The benefit of these projects is that they actually help us to answer the basic questions of existence in a way nothing else does.

While I mostly agree with what you've said in respect to a Mars base -- I think you are leaving out a critical benefit of these types of endeavors.

The technology invented and/or adapted to facilitate these enormous space projects is very often applicable in other fields or daily life.

Some examples from the past include metallic glass (now used in power plants), translucent polycrystalline alumina (now used in invisible braces), water purification technologies, the coatings used on launch pads was adapted for use in coating steel for high-rise building projects, etc. The list is quite long.

There are hundreds of spin-off technologies, many of which are used daily, which originated from various ambitious space projects.

I... Don't think so?

Soviet Union as a materially poor country will not pour so much money into exploring space if it wasn't so important politically at the moment.

The US was much wealthier, but also skipped space spendings the first moment politics no longer persuaded space exploration.

Stuff like GPS and especially Glonass were also borne out of political goals. Same for ISS.

If anything, the only way we may get to explore solar system is via political push.

science is just a spinoff of philosophy which was religiously motivated. what kind of drug-induced state do you have to be in to think that the Romans would have been flying around the Earth if only everyone thousands of years prior was magically a self-absorbed nihilist

I thought that atheists believed that politics and religion have caused most if not all wars in history?

Guess what was the impetus for developing technology? War. i.e. politics by other means. Guess that Stalin developed technology for the love of the game, though. Not for war or politics or anything.

Or are we saying that religion and politics have moderated the impulse to war? i.e. in an ancient atheist world, war would have been much more furious and necessary for survival, so the pressure to develop technology would have been much greater than it was with all those pacifist monks running around spoiling everyone's armed conflict fun with their woo-woo? -- Maybe ICBMs should have been invented around the time that Byzantium was founded

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