The CHRONOS BAG at ESRF is a specialized access mode designed for long-term in situ synchrotron experiments. Its mission is to capture slow processes in real time by enabling continuous X-ray imaging over extended periods. The principle relies on automated, scheduled scans that allow researchers to track dynamic changes in materials under controlled conditions with implications for numerous scientific and industrial fields. In geosciences, it enhances our understanding of fault mechanics, fluid-rock interactions, and carbon sequestration. In material science, it provides insights into creep, fatigue, and phase changes. By bridging timescales and automating data collection, CHRONOS advances synchrotron techniques and opens new possibilities for studying time-dependent natural and manufactured systems.