In consideration of ESA’s contribution to XRISM, not less than 8% of the total Guest Observing Time, or an equivalent return as mutually agreed, shall be allocated to ESA. This time will be allocated by ESA through a competitive process open to the scientific community of the European member states.

Please refer to the specific AO for more details:

1. First announcement of opportunity released on 2023 November 15
2. Second annnouncement of opportunity released on 2025 March 15