Aug 6, 2021

Amendment 29: Updates to D.11 NICER Guest Observer Cycle 4

The Neutron Star Interior Composition Explorer (NICER) is an X-ray experiment on the International Space Station dedicated to high-resolution timing and spectroscopy of neutron stars and other rapidly variable X-ray sources in the 0.2–12 keV band. The NICER Guest Observer (GO) program Cycle 4 solicits proposals for observations with NICER and proposers may also request coordinated Nuclear Spectroscopic Telescope Array (NuSTAR) observations of their proposed NICER targets.

The NICER GO program uses a two-phase proposal process. A Phase-1 proposal shall comprise the science/technical justification. Only proposers whose Phase-1 proposals are selected will be invited to submit budget proposals in Phase 2. The Phase-1 peer review will be executed in a "dual-anonymous" fashion, where not only are proposers unaware of the identity of review panel members, but the reviewers do not have explicit knowledge of the proposal teams

ROSES-2021 Amendment 29 updates D.11 NICER Guest Observer Cycle 4 Sections 1.1, 1.3, and 2.1 to clarify proposal selection and fair share considerations. New text is in bold and deleted text is struck through. The due date for proposals remains unchanged; Phase-1 proposals are due November 10, 2021, via ARK/RPS, see Section 2.2.1.

On or about August 5, 2021, this Amendment to the NASA Research Announcement "Research Opportunities in Space and Earth Sciences (ROSES) 2021" (NNH21ZDA001N) will be posted on the NASA research opportunity homepage at

Technical questions regarding NICER GO may be directed to the NICER PI, Keith Gendreau, at and Programmatic questions may be directed to the NICER Program Officer, Roopesh Ojha, at