Think of a single dish radio telescope as a one-pixel camera, where measuring the emission intensity at each point in the sky lets you build up a map. Typically, this is done with high resolution on the frequency axis, which is used to map Doppler shifts for spectral lines of Hydrogen, for example [1].
With a rooftop antenna, it's not likely to be a very sensitive map, though. You'll see the Sun, and its easy to see the Milky Way transit overhead, but other than that ...
Paraphrasing: "If you don't want to, don't sideload apps, no one is forcing you to" - do people really not see the problem? It's not that technically unsophisticated users will want to sideload apps. They don't know / don't care / have different things to worry about.
But they want their Facebook. Or SnapChat, or Insta, or TikTok, or whatever.
Once other app stores are allowed, there's nothing stopping Meta (for example) from revoking their existing apps, and requiring the use of the Facebook App Installer for access to Facebook. They've paid people in the past to use their Onavo VPN app to bypass Apple's privacy controls, so this would be unsurprising.
Of course, that's just an example; replace with the next SnapChat, TikTok, whatever. If that's the thing that teens want, and the way to get it is to click a bunch of "Yes I agree" dialogs, they'll happily do it. And now suddenly some developer has access to all your family financials through your teen.
If your solution is "well, people shouldn't do that then", you might not understand teens. (Or grandparents. Or regular people.)
Well, there is maybe one thing. That is their projection of reduced installs. It's not just an issue of clicking "Yes". It's probably also an issue of knowing how to do it in the first place. The first party app store will always be easier.
I came to this thread a bit too late, but if you're interested in the actual signal that Stella found, take a look at the spectrum vs time on the NASA release [1] - third plot on the page, with a convenient slider that lets you flip back and forth to see the previously known plasma oscillation events and the newly discovered continuous signal. Notice the huge change in scale!
Allow me to gently contradict the previous responders. The community of radio astronomers is feeling the loss of Arecibo very keenly.
I've mentioned this in a previous comment [1] so I won't rehash it again, but here [2] is a statement from the NANOGrav collaboration - we have been using the Arecibo telescope on a weekly basis (along with the Green Bank telescope) to observe a large number of radio pulsars for over 15 years now, and when we announce the first detection of very low frequency gravitational waves, Arecibo data will play a critical role.
This loss really hurts. The US community is scrambling, and we are going to have to rely on the generosity of our international partners going forward - there's just not going to be enough telescope time to do all the science that we'd judged as very important through competitive review processes.
(And that's before we get into the unique radar capability, etc.)
I would also encourage everyone to read what this loss means to the local communities in Puerto Rico [0], and most particularly, to the young kids who fell inspired by it.
"Kevin Ortiz Ceballos, a physics student and aspiring astronomer at the University of Puerto Rico, said in an email that it had always been his dream to work at Arecibo.
Now he said, “It feels like the rug has been pulled out from under us and our dreams to work in astronomy in Puerto Rico has vanished.”"
Very suspicious in my mind this happened soon after the Chinese 500-meter FAST telescope came online. Is this what you mean by relying on international partners? Maybe it's time for the US to build a new telescope.
I'm too sad today to engage with the discussion here, but I'll just mention, for those of you who think that Arecibo has either "outlived its usefulness" or been supplanted by FAST in China:
Here's Arecibo on the cover of Nature in 2018: [1]. Yes, we are doing similar work at FAST as well, but one is not a replacement for the other.
And here's a link to NANOGrav: [2]. I promise that you'll hear more about NANOGrav in a year or two, depending on how publication timelines work out. And it wouldn't be possible without Arecibo - now that it's gone, we have to seriously contemplate how to move on beyond our 15-year data set (already in the can).
I'm too sad today to engage with this, but you're simply wrong about Arecibo "having done all the useful things it could do ages ago, and not finding anything new".
Here, for example, is Arecibo on the cover of Nature, in 2018: [1].
And you might want to look into NANOGrav [2]: you'll be hearing a lot more about it (I promise) in one or two years, depending on publication timelines.
Despite its large instantaneous sensitivity, Arecibo is not really suited for transient work. In the FRB example Arecibo has a factor 22 advantage in collective area and yet trails Parkes by a factor of 14 in number of discovered FRBs: weak evidence of a unique capability.
And it's too bad the NANOGrav risks getting its results delayed by the inability to extend observations on half its sources, but the loss of Arecibo will not doom the entire project: again not conclusive proof that Arecibo added a unique capability.
There is a sea of difference between your initial statement of "having done all the useful things it could do ages ago, and not finding anything new" and your new statement of wanting conclusive proof that Arecibo has "a unique capability".
The "proof" shows Arecibo was still very useful and finding new things and this disaster will significantly delay research. (As a side note; delays in research can easily mean the death of that research as funding is often time-bound)
Somewhere in this there is a larger story of useful projects not receiving enough funding because they aren't sexy enough.
> If the full hundred hours was such a huge risk, why not take, like, 5-10 photos first to see if you get much of anything? Seems like they would have been able to know pretty early on whether it was going to be worth it.
This has been answered already but just to pull some threads together - the suggestion to take a few exposures first and see what comes out is precisely backwards. They already knew, going into it, that what they were looking for was at the limits of sensitivity, so nothing would show up until they accumulated enough observing time.
In the absence of systematic effects, our signal to noise ratio improves as the square root of integration time. Think of a bucket accumulating photons - the signal accumulates in linear proportion to the integration time, while the RMS fluctuations increase as the square root of the integration time, so the signal to noise ratio improves as T/sqrt(T) = sqrt(T).
So the idea was to accumulate enough exposure that the faint galaxies would become visible at the telescope performance limits - can't get to something scientifically useful by imaging only the first few exposures. It might have made a pretty enough picture, sure, but not an informative one, compared to what we could already do from huge ground-based facilities.
HST is in a 96-minute orbit, up to half of which is blocked by the Earth, depending on where in the sky you point it. Getting time on it is an extremely competitive process - the recent cycle had over a thousand proposals, requesting over 24,000 orbits worth of observing time, and they had only 2700 orbits to allocate [1].
This sort of proposal pressure (over 9:1 oversubscription) leads to very conservative proposals, where we request absolute minimums and emphasize that even a non-detection will lead to publishable science in such and such a way.
Getting over 60 orbits to point at a blank field would have been frankly impossible through the regular time allocation process, not because the science wasn't excellent, not because it wouldn't be recognized as excellent, but because it would crowd out other science that could be done with far fewer orbits per project.
The telescope administrators explicitly recognized this problem when they set up the Director's Discretionary Time process (and this is common to all telescopes now) - sometimes you need someone with the authority to just roll the dice on a long shot.
Think of a single dish radio telescope as a one-pixel camera, where measuring the emission intensity at each point in the sky lets you build up a map. Typically, this is done with high resolution on the frequency axis, which is used to map Doppler shifts for spectral lines of Hydrogen, for example [1].
With a rooftop antenna, it's not likely to be a very sensitive map, though. You'll see the Sun, and its easy to see the Milky Way transit overhead, but other than that ...
[1] https://sites.google.com/site/galfahi/