The NANOGrav (North American Nanohertz Observatory for Gravitational Waves) consortium is timing an array of very stable millisecond pulsars to try to detect gravitational waves. NANOGrav in turn is part of the larger International Pulsar Timing Array (IPTA) consortium.
Fun Sonic Exercise
Links
Legacy/archival links related to NANOGrav Arecibo pulsar timing:
This work is funded by grants from the National Science Foundation.