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NICER Mission Timeline

Current Activity

NICER Observing Timeline. Please see Upcoming and recent past pointings for up-to-date NICER observation scheduling. For the final as-flown timeline, you can use the HEASARC Timeline Tool, which is populated within two weeks of observation.

Targets of Opportunity and Directory's Discretionary Time. Details of previously submitted TOO/DDT requests are available at the TOO Summary page. Please review the NICER ToO Policy. Any questions regarding how to make TOO requests should be sent to the NICER Helpdesk via the HEASARC's Feedback Form.

MAXI OHMAN Targets. Summary of OHMAN Targets observed by NICER: OHMAN (Orbiting High-energy Monitor Alert Network) X-ray follow-up observation program uses JAXA's MAXI all-sky monitor to detect sudden X-ray bursts and to automatically notify NICER for immediate followup. See the OHMAN Summary page for a list of OHMAN triggers.

NICER Enhanced Visibility Calculator

The NICER Enhanced Visibility Calculator calculates visibilities for targets over roughly the next 2-week period taking into account ISS orientation and target occultation by ISS structures and other relevant constraints. These visibility intervals are more accurate than visibilities based solely on Sun and Moon avoidance.

Other NICER Activities

Early Post-Launch NICER activities

  • July 13 Begin Science Program
  • June 21-July 12 Initial calibration and hardware commissioning
  • June 17 NICER uses Raster scan of Serpens X-1 to determine X-ray instrument and star tracker alignment
  • June 14 NICER is powered up, NICER is deployed, NICER range of motion is verified by robotic camera
  • June 12-13 NICER is installed on the ISS ELC2
  • June 11 2017 NICER is extracted from the Dragon trunk

Latest News

  • NICER AO8 Selected Proposals (26 Jan 2026)
    The proposal selection process for Cycle 8 is complete, and a list of selected proposals is now available.
  • NICER suspends science operations (17 Jun 2025)
    NICER science observations were suspended on June 17, 2025 due to degradation in the payload's pointing performance. The NICER team is investigating this issue. We regret that we are unable to accept target-of-opportunity observation requests at the present time.
  • Following repair, NICER improves daytime measurements (23 Apr 2025)
    NICER has regained additional daytime observation capabilities thanks to repairs completed during a spacewalk in January and a reconfiguration of its detectors.
  • NICER Patching Assessment after Spacewalk 91 (24 Jan 2025)
    Verification observations of the installation of 9 patches during U.S. Spacewalk 91 show that the detectors behind the patched optics are receiving lower levels of optical light during orbit night, and the level of light inside the instrument during orbit day is substantially reduced. Some continued data degradation due to sunlight during orbit day is, however, still evident. NICER continues to operate with its full measurement capabilities during orbit night, and assessment of daytime data recovery is ongoing.
  • Patching NICER (17 Jan 2025)
    During EVA 91 on January 16, 2025, ISS Astronaut Nick Hague successfully installed 9 patches into 8 of the NICER XTI sunshades to mitigate light leaks from damaged portions of the optical blocking filters. You can watch a recording of the NICER portion of the spacewalk activity from Nick Hague's helmet-camera.

[More NICER News]