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Comment by chongli | Hacker News Reader

Surprised to see no mention of tourists or cellphones. We learned about this telescope in astronomy class on Tuesday and our professor said the place was inundated with so many tourists that it was impossible to get any useful data due to the noise generated by all the cellphones. Part of the reason the telescope was built in such a remote area was to reduce the amount of radio noise from terrestrial sources.

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That's surprising. I went there recently, and you aren't permitted to bring any electronic devices whatsoever - you have to leave them in a locker and then take a ~30 minute bus ride to the telescope.

They're also very strict about checking: you have to go through two different x-ray machines to check you didn't sneak any electronics through.

Perhaps the no-devices policy was introduced after the interference issues were encountered?

No, the no devices policy would have been there from the start, its as basic as forbidding open flames at a petrol station.

The need for X-ray machines due to tourists ignoring the ban is a more likely development.

Are those truly x-ray machines? Not just magnetic coils? Seems overkill and I'd object to being exposed to ionizing radiation just for the purpose of validating my claim that I don't carry any electronic communication devices.

Most likely it's X-rays for your stuff and metal detectors to make sure you're not trying to smuggle anything past the X-ray machine.

It's actually a pretty standard setup in China anyway... Pretty much anytime you go onto an inter-city bus / train or into a crowded space (museum / exhibition centre) you will go through a metal detector and your bag through an x-ray machine. So it makes sense that they'd just use the standard setup that the local security company would be used to.

No, it wasn't there from the start. The no electronics policy only started within the last two years. I know someone who has been there and has the pictures on her phone.

Maybe the tourists are present only a few hours in certain days. The article mentioned some discoveries so it must be working.

Those 'discoveries' are just confirmations of prior discovery by other telescopes of a particular repeating fast radio burst.

You can't discount it that easily: they report bursts unobserved by other instruments, which could be a second burst mechanism that hasn't been seen before due to its lower flux.

Also FAST has discovered about 100 new pulsars, in at least one case they detected a pulsar at a position Arecibo had observed three times already and not finding anything.

And that is as expected, the article mentions that this telescope is more sensitive but it has a smaller field of view so it is used to get better images of areas indicated by a different telescope that has a much larger field of view.

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