NuSTAR has been approved to continue operations through 2025 based on the outcome of the 2022 NASA Astrophysics Senior Review of Operating Missions (the report pdf file is available here) and includes a General Observer (GO) Program.
Last updated: 2025-09-08
A list of proposals and targets selected for NuSTAR GO cycle-11 is available on the NuSTAR HEASARC website.
NuSTAR GO cycle-12 proposals are due on January 29th, 2026, independent peer review will be in 2026 spring, and the selection should be announced in May, 2026 for observations beginning in June, 2026.
Future opportunities to propose for NuSTAR observing time (contingent on results of 2025 Senior Review of operating missions)
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Up to 6500 ks of NuSTAR observing time for standard proposals (< 500 ks) and 2000 ks of NuSTAR observing time for large proposals (> 500 ks) is available. Joint observing time is available for XMM-Newton (up to 1500 ks) and Gehrels-Swift (up to 150 ks) is also available in the NuSTAR GO program. Proposal due date: January 29th, 2026 for observations beginning June, 2026. |
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Up to 500 ks of NuSTAR observing time available for standard proposals and an additional 500 ks of NuSTAR time available in the Large/Very large program Proposal due date: March 2026 for observations beginning January, 2027. |
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| IXPE cycle-3 | Up to 500 ks of NuSTAR observing time available
Proposal due date: September 11th, 2025 at 4:30pm EDT (past) for observations beginning February, 2026. |
| Gehrels-Swift cycle-22 | Up to 150 ks of NuSTAR observing time available
Proposal due date: September 11th, 2025 at 4:30pm EDT (past) for observations beginning April, 2026 |
| XMM-Newton cycle-25 | Up to 1500 ks of NuSTAR observing time available
Proposal due date: October 10th, 2025 (1200 UT) for observations beginning May, 2026 |
The NuSTAR GO program
The total amount of time allocated to GO observations is 11.3 Ms (~70% of the total observing time per year) including up to 8.5 Ms of observing time awarded to selected NuSTAR GO program investigations. It is anticipated that approximately 80 investigations will be selected for implementation in each NuSTAR GO cycle.
Of the remaining time (~ 2.8 Ms):
- up to 1.5 Ms of NuSTAR observing time is expected to be awarded to joint NuSTAR/XMM-Newton proposals submitted to annual XMM-Newton Call for Proposals with proposals due in October each year. The list of accepted proposals for cycle-24 is available on the XMM-Newton OTAC results website.
- up to 500 ks of NuSTAR observing time for joint NuSTAR / Chandra observing projects submitted to the Chandra Call for Proposals. Note that an additional 500 ks may also be allocated for Chandra V/LP programs. See CXC website for cycle-27 peer review recommended programs for observations in 2026. The annual due date for Chandra proposals is in March each year.
- Note: INTEGRAL has completed the final two months of science operations and is now decommissioned (as of March 2025). In the past, up to 100 ks of NuSTAR observing time was made available for joint NuSTAR / INTEGRAL.
- up to 150 ks of NuSTAR observing time for joint NuSTAR / Swift proposals is available in Swift cycle-22, with proposals due in September each year. A list of proposals selected for cycle-21 is available on the Swift website.
- Note that as a service to the community, "snapshot" (1 - 2 ks) observations are performed by NASA’s Swift mission for most NuSTAR observations (including GO programs).
- In the past, up to 400 ks of NuSTAR observing time for joint NuSTAR / NICER proposals has been available in NICER GO cycles. No new observing proposals are being accepted for cycle-8 (2026). The list of accepted proposals for cycle-7 is available on the NICER GO website.
- up to 500 ks of NuSTAR observing time for joint NuSTAR / IXPE proposals is available in IXPE cycle-3, with proposals due in September each year. The list of recommended targets for cycle-2 is available on the IXPE GO website.
For the most complete list of planned and observed targets, as well as any ToOs that may be triggered before the beginning of cycle-11 observations on June 1st 2025, please refer to the NuSTAR Master Catalog at the HEASARC, which may be queried using either Browse or Xamin. The full list of approved NuSTAR ToO programs is available on the NuSTAR SOC website.
The remaining 30% of the observing time will be allocated through the NuSTAR project as follows:
- NuSTAR legacy survey observations (~ 3% of the total observing time)
- NuSTAR PI discretionary time, including unanticipated ToO observations open to the scientific community (~ 17%)
- Calibration observations, engineering tasks, and resolving operational issues (~ 10%).
Please see the NuSTAR HEASARC Page for the latest information about NuSTAR.
Useful links: