Source needed.

> The Arecibo telescope had been upgraded regularly, with several new instruments slated for installation in the coming years. “The telescope is in no way obsolete,” says Christopher Salter, an astronomer at the Green Bank Observatory, who worked at Arecibo for years.

From what I understand this is not the case. There is no replacement for some of the work this telescope could do, mostly around the ability to also act as a giant RADAR with its powerful transmitters.

Where did you get the idea that the technology's been superseded?

The NANOGrav collaboration is trying to use millisecond pulsars to determine if a galaxy-wide analysis of 47 pulsars can detect gravitational waves.

The team says that Arecibo was instrumental for their data analysis because the telescope was unique in its radio sensitivity:

"Although NANOGrav does not expect the situation to result in significant delays in detection due to years of very sensitive Arecibo data already contributing to their datasets, the loss of Arecibo is a terrible blow to science, and will impact NANOGrav’s ability to characterize the background and detect individual sources in the future."

http://nanograv.org/press/2021/01/11/12-Year-GW-Background.h...