SPT-SLIM: using on-chip mm-wave spectrometers for line intensity mapping from the South Pole

The South Pole Telescope Summertime Line Intensity Mapper (SPT-SLIM) is a pathfinder instrument that will observe on the 10-m South Pole Telescope in the 2024-2025 austral summer. The instrument consists of 12 dual-polarization pixels spanning 120-180 GHz with an R = 200 filterbank spectrometer coupled to aluminum kinetic inductance detectors. These spectrometers will be deployed in a compact 100 mK cryostat, located to intercept the main beam of the SPT without disturbing the SPT-3G experiment. The SPT-SLIM frequency range will be sensitive to the carbon monoxide (CO) line emission from high-redshift galaxies, paving the way for future high-redshift cosmology experiments. I will summarize the cryostat, optical design and commissioning status, present detector performance, and discuss the deployment and observation plans for the 2024-2025 austral season.