First Announcement of Opportunity


After the successful launch of XRISM on September 7, 2023 and the completion of the critical operation period, the first Announcement of Opportunity for the Guest Observer program opens November 15, 2023.

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. The ESA Director of Science has thus issued the invitation to submit Guest Observer proposals for the observation period between July 2024 and June 2025: Letter by ESA Director of Science

Please find all instructions to submit proposals in this document: Announcement of Opportunity for the XRISM GO program.

Further information about XRISM can be found in this XRISM Quick Reference guide.

Information for studies of feasibility can be found under XRISM Proposal Tools


Major Milestones:

7 December 2023  Target for the publication of the Proposal Observer Guide and the opening of the proposal submission tool (ARK/RPS)
22 February 2024  12:30 CET                               The due date for proposals


The page limit for the science justification is 4 pages. A (not mandatory) LaTeX template is available.

For any questions, the European community is encouraged to make use of the European XRISM User Support Portal.