Big respect for the technology that makes such imaging possible:
Because the black hole is about 27,000 light-years away from Earth, it appears to us to have about the same size in the sky as a donut on the Moon. To image it, the team created the powerful EHT, which linked together eight existing radio observatories across the planet to form a single “Earth-sized” virtual telescope [1]. The EHT observed Sgr A* on multiple nights, collecting data for many hours in a row, similar to using a long exposure time on a camera.
And just like a high-powered camera, imaging Sgr A* required the support of the most sensitive instruments in radio astronomy. That sensitivity comes from the 1.3mm Band 6 receivers on the Atacama Large Millimeter/submillimeter Array (ALMA), designed by the Central Development Laboratory (CDL) at the US National Science Foundation’s National Radio Astronomy Observatory (NRAO).
“We are very proud at CDL to have provided some critical technology to support this amazing discovery by the EHT collaboration,” said Bert Hawkins, Director of CDL, who explained the role of Band 6 and CDL in making the research and the results possible. “Our team contributed by installing a custom-built atomic clock on ALMA and reprogramming the ALMA correlator to make the telescope a phased array. This effectively turned the telescope into a single dish with an effective diameter of 85 meters– the largest component on the EHT. In addition, the mixers at the heart of the receivers on ALMA, the Submillimeter Telescope (SMT) in Arizona, the Large Millimeter Telescope (LMT) in Mexico, and the South Pole Telescope (SPT) in Antarctica were developed at CDL along with our partners at the University of Virginia.”
