In August 2008, OSU was approached by NOAO (now NOIRLab) to build two new facility spectrographs for the 4m Mayall telescope at Kitt Peak and the 4-m Blanco telescope at CTIO based on the design of OSMOS to provide a modern, high-efficiency spectrograph for the U.S. community that would meet most of the scientific requirements described in the NSF ReSTAR (Renewing Small Telescopes for Astronomical Research) Report.

OSU designed a new optical system with oil-coupled lenses to adapt the OSMOS architecture for the 4-m telescopes, built the mechanisms and control systems, and did final assembly and integration. The CCD detector package and data-acquisition software was provided by NOAO.  The K/COSMOS spectrographs provide spectral resolutions of 1800-4000 in the 320-980nm range with either long-slits or laser-cut multi-slit masks.

The KOSMOS spectrograph was commissioned on the 4-m Mayall telescope at Kitt Peak in October 2013 where it operated until its retirement in 2018 when the Mayall began to be reconfigured for the DESI project.  It was acquired by the University of Washington in 2019 and modified to work on the ARC 3.5m telescope at Apache Point Observatory where it was commissioned in 2021 and began science operations.

The COSMOS spectrograph as commissioned on the 4-m Blanco telescope at CTIO later in September 2014 and continues in operation to the present day.