NuSTAR Proposals and Tools


While NuSTAR was initially approved by NASA as a 2-year Principal Investigator-led (PI-led) mission, NuSTAR has now been approved to continue operations through 2018 (subject to review by the 2016 NASA Astrophysics Senior Review of Operating Missions) and to have a dedicated Guest Observer (GO) Program. There are several opportunities for guest observers in the general scientific community to propose for NuSTAR observations.

NuSTAR Guest Observer Program

Additional opportunities to propose for NuSTAR time:


NuSTAR Guest Observer (GO) Program

Starting in 2014, NuSTAR solicited guest observer proposals from the general scientific community. Proposals are solicited via NASA's ROSES grant solicitation process. The proposal process is divided into two phases. A Phase 1 proposal is submitted to NASA HEASARC's ARK system, containing detailed target selection forms and a concise science justification. Proposals may come from both US and non-US researchers. Phase 1 proposals are evaluated by peer review panels. Data from approved GO observations, with the exception of Target of Opportunity (ToO) observations, have a nominal one-year exclusive-use period commencing at the time of receipt of the processed data by the observer. Data from peer review approved ToO observations have a six-month exclusive-use period.

NASA also provides grant funding to support certain selected proposals. These funds are limited to proposals with PIs at US institutions. Selected proposals will receive a notification letter with more details and an invitation to submit a Phase 2 (budget) proposal. Phase 2 proposals are submitted to NASA's NSPIRES system.

Cycle 3

DateImportant Cycle 3 Event
February 19th, 2016NuSTAR Cycle 3 Announcement of Opportunity
Late October, 2016Cycle 3 phase 1 proposal submissions open
January 25th, 2017Last day to request assistance for pointings with potential stray light
January 27th, 2017Cycle 3 phase 1 proposals due 4:30pm EST
Early April, 2017Cycle 3 peer review

Cycle 2

DateImportant Cycle 2 Event
February 13th, 2015NuSTAR Cycle 2 Announcement of Opportunity
September 10th, 2015Cycle 2 phase 1 proposal submissions open
December 9th, 2015Last day to request assistance for pointings with potential stray light
December 11th, 2015Cycle 2 phase 1 proposals due 4:30pm EST
February 17-19, 2016Cycle 2 peer review
April 27, 2016Notification letters sent to PIs
May 1, 2016Approximate start of Cycle 2 guest observations
June 10, 2016Phase 2 (budget) proposals due in NSPIRES for non-ToO or non-Time constrained (TC) proposals ranked as Category A or Category B

Phase 2 Budgets. Proposers eligible for NASA funding should have received additional information about submitting a Phase 2 (budget) proposal in their notification letters. For more information, see the the guide for NuSTAR cycle 2 proposers.

Cycle 1

DateImportant Cycle 1 Event
August 26th, 2014NuSTAR Cycle 1 Announcement of Opportunity
September 17th, 2014List of planned NuSTAR targets released
November 24th, 2014Last day to request assistance for pointings with heavily contaminated stray light
November 25th, 2014Cycle 1 phase 1 proposals due 4:30pm EST
February, 2015Approximate date of Cycle 1 peer review
April 1, 2015Approximate start of Cycle 1 guest observations
April 3, 2015Cycle 1 accepted targets posted
April 17, 2015Notification letters sent to PIs
May 29, 2015Phase 2 (budget) proposals due in NSPIRES for selected proposals

Phase 2 Budgets. Proposers eligible for NASA funding should have received additional information about submitting a Phase 2 (budget) proposal in their notification letters. For more information, see the the guide for NuSTAR cycle 1 proposers.


Proposal Tools

The NuSTAR project has developed tools and documentation to help potential proposers.

NuSTAR Observatory Guide: The NuSTAR team has developed a document which describes the technical capabilities, concept of operation and key information for proposers. Download the current version NuSTAR Observatory Guide (7.3 MB pdf file) (released June 2016).

Count Rate and Spectral Simulations: The standard HEASARC count rate and spectral simulations tools, WebPIMMS and WebSpec, are available for NuSTAR simulations. WebSpec was updated on March 5, 2014 to include the most recent NuSTAR responses and background files. The NuSTAR responses and background files can also be downloaded directly from the Caltech SOC web site and used to simulate spectra in spectral analysis software such as XSPEC. See Section 4.7 of the NuSTAR Observatory Guide for a detailed discussion of how to simulate NuSTAR spectra using XSPEC. If detailed background modeling is required, the "nuskybgd" NuSTAR background simulation toolkit is is available from the User-Contributed NuSTAR Software page.

Other issues which proposers should take under consideration are:

  • Target Visibility: The NuSTAR Science Operations Center Target Visibility checker allows input of the RA and Dec coordinates of a source and finds the times when it is visible to NuSTAR subject to viewing constraints.
  • Timing: The NuSTAR Clock Correction Files keep the NuSTAR relative time (after barycentric corrections) accurate to ~2 ms and account for drifts in the NuSTAR clock caused by temperature variations, etc. New clock files will be produced as the mission continues on a ~monthly basis.
  • Stray Light: Extremely bright X-ray sources (>100 mCrab in the 3-79 keV band) within 1 to 5 degrees of a target can cause issues with elevated backgrounds due to stray light. The presence of such confusing sources is reported by the NuSTAR Science Operations Center Target Visibility checker.
  • Dead Time: NuSTAR has a triggered readout, similar to a proportional counter but unlike a CCD, so it does not suffer from pile-up effects. However, dead time becomes significant for sources above ~50 ct/s, and this must be factored into integration time estimates. Quantitative estimates of the effect of dead time on exposure estimates are included in the latest version of WebPIMMS. Further details of the effects of dead time on bright source count rates can be found in this memo (pdf).

No-Cost Extensions

If you would like to file a no-cost extension, please take at https://answers.nssc.nasa.gov/app/answers/detail/a_id/5907. To request a No-Cost Extension please go to: https://www.nssc.nasa.gov/nocostextension.


Additional opportunities to propose for NuSTAR time

Joint INTEGRAL and NuSTAR Observations

In the INTEGRAL Fourteenth Announcement of Opportunity released on February 29th, 2016, ESA is providing the opportunity to propose for coordinated observations of INTEGRAL with NuSTAR for a total of 100 ks of available time. The deadline for INTEGRAL AO-14 proposals is April 8th, 2016.

Joint XMM-Newton and NuSTAR Observations

Currently NuSTAR and XMM-Newton have an arrangement which makes available joint observing time for both observatories. This resource allows observers to combine the powers of both observatories to bear on their scientific problems. This resource is extremely limited, so proposers should be sure to describe how their proposed observations exploit the unique capabilities of both observatories. While joint XMM-Newton and NuSTAR proposals within the NuSTAR Guest Observer Program are now also possible, proposals for additional observation time can go through the XMM proposal process.

  • XMM Cycle 16. Is now closed. Approximately 1.5 Ms of joint XMM-Newton and NuSTAR observation time was made available through the XMM-Newton Cycle 16 AO. The start of observations is in May 2017.
  • XMM Cycle 15. Is now closed. Approximately 1.5 Ms of joint XMM-Newton and NuSTAR observation time was made available through the XMM-Newton Cycle 15 AO. The start of observations is in May 2016. Results can be found on the XMM-Newton OTAC Results page.
  • XMM Cycle 14. Is now closed. Approximately 1.5 Ms of joint XMM-Newton and NuSTAR observation time was made available through the XMM-Newton Cycle 14 AO. The start of observations is in May 2015.
  • XMM Cycle 13. Is now closed. Approximately 1.5 Ms of joint XMM-Newton and NuSTAR observation time was made available in the XMM-Newton Cycle 13 AO which was released on 27 August 2013. 62 such proposals were in fact submitted. Results can be found on the XMM-Newton OTAC Results page.

Joint Chandra and NuSTAR Observations

Currently NuSTAR and Chandra also have an arrangement which makes available joint observing time for both observatories. An opportunity to propose for NuSTAR observing time as part of this joint observing program is being made available through the Chandra calls for proposals.
  • Chandra Cycle 18. Is now closed. Up to 500 ksec of NuSTAR observing time was made available through the Chandra proposal process, which closed on March 15, 2016.
  • Chandra Cycle 17. Is now closed. Up to 500 ksec of NuSTAR observing time was made available through the Chandra proposal process, which closed on March 17, 2015.
  • Chandra Cycle 16. Is now closed. Up to 500 ksec of NuSTAR observing time were made available through the Chandra proposal process, which closed on March 13, 2014. Results of the review can be found here.

Unsolicited NuSTAR Target of Opportunity (ToO) or Directors Discretionary Time (DDT) Observations

A total of at most 500 ks of observing time will be made available to ToO proposals in the GO program. However, unsolicited ToO requests for exceptional transients will continue to be possible through the NuSTAR ToO web site, even for those not accepted into the GO Program. The decision on whether or not to observe a ToO of either category will be made by the NuSTAR Principal Investigator or her official designee. Such ToO requests are unfunded and do not have an exclusive-use period.


If you have any questions concerning NuSTAR or the NuSTAR GO program, visit the Feedback form.