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This is how scientists turned the world into a telescope (to see a black hole)



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It took eight telescopes around the globe a week of observations to produce the black hole image That surprised the world last week, but it took scientists much longer to teach these instruments to work together.

And in the two years since the data was collected behind that image, the Event Horizon Telescope The partnership behind the innovative observations has already expanded, with more telescopes looking to join the fray soon. Each new instrument will sharpen the images of the scientists from its quarry, but each one must also be carefully equipped before it can join the quarry. collaboration.

Fortunately, the hardest work is already done, Dan Marrone, an astronomer at the University of Arizona and a member of the Horizon Horizon Telescope's scientific team, told Space.com. "For the most part, the sites we're adding now are just reimplementing the basic hardware that we know how to do well," he said.

Related: Eureka! Scientists photograph a black hole for the first time

But the more telescopes the equipment can carry on board, the sharper the final image will be. The challenge in doing this comes from the fact that none of these telescopes was custom-made for the Horizon telescope project event. They are just instruments that are what scientists call submillimeter telescopes, which can detect the range of wavelength that the members of the Event Horizon team needed to tune in to hunt for black holes.

For the South Pole telescope, then, the team needed to adapt a telescope designed to study the remains of the Big Bang, installing a special detector and an optical package. All of which, of course, had to endure the extreme cold of Antarctica.

The Event Horizon Telescope, a planetary-scale set of eight terrestrial radio telescopes forged through international collaboration, captured this image of the supermassive black hole at the center of the M87 galaxy and its shadow.

(Image: © EHT Collaboration)

And the instruments involved in the observations included single-dish telescopes and multidish arrays. That posed a particular challenge in the Atacama Large Millimeter / submillimeter Array (ALMA) At the top of the Chilean desert, where the information of the different dishes should be compiled to perfection.

So, each of the instruments needed to be armed with a atomic clock so precise that loses only 1 second every 100 million years. The time of the clock must be printed on all observations of the telescope so that when scientists combine the data collected by the different telescopes, the observations are not blurry.

The other crucial equipment that the team needed to install on each instrument was a system that could keep up with the massive flow of data that occurs: 16 gigabits every second of the observation period, significantly more than other astronomy projects, Marrone said. . That required tailored recording systems of commercial components.

The Event Horizon Telescope team has already equipped a newcomer in this way: the Greenland Telescope, which went online for the 2018 observation campaign of the program. The addition posed its own challenges: the telescope was originally built as a prototype for the ALMA plates, then equipped to withstand the cold and sent to Green land and configure as part of the Event Horizon Telescope.

That addition improved the team's observations of the northern part of M87, extending the coverage of the matrix to the north. Another next addition, from the Kitt Peak telescope in Arizona, it will reinforce the matrix in the opposite way, partnering with the nearby Submillimeter Telescope to offer redundancy to scientists, helping the team calibrate observations. "If we could choose our set, we would have two telescopes in each site," said Marrone.

While there are many schemes on how to organize a collection of networked instruments, the team is not really that demanding: more telescopes will always help your resolution, no matter where you are. "The terrain of the Earth does a good job of random assignment where we can locate them," said Marrone.

But there is no reason why the Horizon Event Telescope should always be on Earth. Currently, there are no submillimeter telescopes in orbit, but some team members are investigating proposing such an instrument. "It does not take much of a telescope," said Marrone. "It's not a fairly Cuban scale, but it's not JWST," he added, referring to the massive, over-budgeted and delayed James Webb space telescope that is currently scheduled for launch in 2021.

And perhaps a space collaborator would address some of the mundane challenges that pursue Marrone and her colleagues during their search to see what can not be seen. This is because the process requires collecting data, multiplying it thousands of times and then clarifying a perfect, rhythmic and symmetrical sinusoidal wave from it.

"The amount of days I spent trying to figure out what it was that was doing to move my sine wave, can be really painful," Marrone said. the guilty it can go from someone who steps on a wire or jumps near an atomic clock, to the wind that blows too hard or two pieces of metal that touch each other when they should not.

"Doing this is a really strange job," said Marrone. "It's all these small, stupid problems that we always have to solve to make this work." But when it works, it's worth it.

Email Meghan Bartels in mbartels@space.com or follow it @meghanbartels. Follow us On twitter @Spacedotcom and in Facebook.

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