Science commissioning and first results from the next generation Gemini High Resolution Optical Spectrograph (GHOST)

The Gemini High Resolution Optical Spectrograph (GHOST) is the next generation high resolution spectrograph for the Gemini South Observatory, and this has recently been commissioned in May 2021. In a single exposure, it can obtain the full optical spectrum from blueward of 360nm to beyond 1 micron. Two modes of operation mean that either one object can be observed at R~80000, or two objects can be observed at R~55000. First light results have tested all aspects of the scientific performance of GHOST from the science user perspective, including a range of aquisition procedures and its two spectral resolution modes. On-sky observations of scientific and library targets reveal GHOST to be the most sensitive spectrograph across the full optical range of any of the 8-10m class spectrographs currently in operation. This paper presents a full discussion of the commissioning process, tests, on-sky performance and first science observations.