Its discovery was announced in 2003. PSR B1620-26 b (bautizado de manera oficial como Matusalén), es un planeta extrasolar que fue detectado a través de los cambios Doppler que ejercía sobre las señales de radio emitidas por la pareja de púlsares PSR B1620-26. Its mass is 2.5 Jupiters, it takes 95 years to complete one orbit of its star, and is 23 AU from its star. PSR B1620-26 is a binary star system, located in the constellation of Scorpius in the globular cluster Messier 4 (NGC 6121). PSR B1620-26 b is a gas giant exoplanet that orbits an unknown-type star.
It is located around 12,400 light years (3,800 parsecs) from Earth.The system is composed of a pulsar (PSR B1620-26 A) and a white dwarf star (WD B1620-26 or PSR B1620-26 B).