The CLASSIC and CLIMB beam combiners of the CHARA Array are open air, aperture plane, wide bandwidth single spectral channel instruments optimized for sensitivity. CLASSIC is the original two beam combiner used for the first science at CHARA, and it still has the faintest magnitude limit. CLIMB is a three beam expansion of CLASSIC that can also provide closure phase measurements.

CLASSIC/CLIMB Instrumentation Paper (pdf) ---  ten Brummelaar, T.A., et al. 2013, JAI, 240004

CHARA CLASSIC/CLIMB Data Reduction Page