MUSTANG 2: A Large Focal Plane Array for the 100 m Green Bank Telescope

This paper describes MUSTANG 2, a 338 element focal plane array that is being built for the Green Bank Telescope. Each element consists of a profiled feedhorn coupled to two transition edge sensor bolometers, one for each polarization. Initial deployment will be with 32 detectors, but once fully populated, MUSTANG 2 will be capable of mapping a $$8'\times 8'$$8′×8′ area to $$23~\upmu $$23μJy in 1 h with good image fidelity on angular scales from $$9''$$9′′ to $$6'$$6′. As well as an instrument overview, the choice of bandpass and the design of the feeds, detectors and readout are given.