We propose a series of two team meetings at ISSI (Bern), aimed at discussing the issue of spin measurements in stellar mass and supermassive accreting compact objects. These meetings will bring together a selected number of geographically-scattered senior scientists, both observers and theoreticians, as well as young scientists who are actively working on the topic. This team meeting will provide a framework for broad discussion that will help shape up the research on the topic in the next 5 to 10 years, and is intended to allow results which are not within reach of smaller local collaborations. We will address a few major questions. 

  • What is the agreement on the methods currently used to measure spin of accreting compact objects? What is the level of detail that can be currently reached with theoretical models and how these models influence the understanding of the spin-related physics? These questions are important to consolidate results on relativistic effects such as the presence of an innermost stable orbit or the measurement of black-hole spins. 
  • What links can be made between the different models and methods? Can relativistic measurements with different methods be reconciled? The outcome of this meeting will help define strategies and instrumentation set ups for upcoming high-energy missions.