The Neutron star Interior Composition ExploreR Mission


Current Activity:

Current time (UT): 2017-12-14 02:34:10
NICER most recent pointing: BKGD_RXTE_5 From: 2017-12-14T02:32:24 until: 2017-12-14T02:35:26
Next pointing: PSR_J0030+0451 At: 2017-12-14T02:36:00 until: 2017-12-14T02:41:40

Targets of Opportunity (ToOs) Capability with NICER
NICER is capable of following up on Targets of Opportunity (ToO) within 4 hours (depending on source visibility). E-mail TOO requests to:

Keith Gendreau (keith.c.gendreau@nasa.gov) or Zaven Arzoumanian (zaven.arzoumanian@nasa.gov)

The NICER team monitors the Gamma-ray Coordination Network (GCN)/Transient Astronomy Network (TAN).

NICER was launched aboard a SpaceX Falcon 9 rocket on June 3, 2017 at 17:07 EDT (21:07 UTC)


The Neutron star Interior Composition Explorer (NICER) is an International Space Station (ISS) payload devoted to the study of neutron stars through soft X-ray timing. Neutron stars are unique environments in which all four fundamental forces of nature are simultaneously important. They squeeze more than 1.4 solar masses into a city-size volume, giving rise to the highest stable densities known anywhere. The nature of matter under these conditions is a decades-old unsolved problem, one most directly addressed with measurements of the masses and, especially, radii of neutron stars to high precision (i.e., better than 10 percent uncertainty). With few such constraints forthcoming from observations, theory has advanced a host of models to describe the physics governing neutron star interiors; these models can be tested with astrophysical observations.

NICER will enable rotation-resolved spectroscopy of the thermal and non-thermal emissions of neutron stars in the soft (0.2-12 keV) X-ray band with unprecedented sensitivity, probing interior structure, the origins of dynamic phenomena, and the mechanisms that underlie the most powerful cosmic particle accelerators known. The NICER mission achieves these goals by deploying an X-ray timing and spectroscopy instrument on the International Space Station (ISS).

By answering a long-standing astrophysics question - How big is a neutron star? - NICER will confront nuclear physics theory with unique measurements, exploring the exotic states of matter within neutron stars through rotation-resolved X-ray spectroscopy. The capabilities that NICER brings to this investigation are unique: simultaneous fast timing and spectroscopy, with low background and high throughput. NICER will also provide continuity in X-ray-timing astrophysics more broadly, post-Rossi X-ray Timing Explorer, through a Guest Observer program. Finally, in addition to its science goals, NICER will enable the first space demonstration of pulsar-based navigation of spacecraft, through the Station Explorer for X-ray Timing and Navigation Technology (SEXTANT) enhancement to the mission, funded by the NASA Space Technology Mission Directorate's Game-Changing Development program.

NICER's X-ray Timing Instrument (XTI) represents an innovative configuration of high-heritage components. The heart of the instrument is an aligned collection of 56 X-ray "concentrator" optics (XRC) and silicon drift detector (SDD) pairs. Each XRC collects X-rays over a large geometric area from a roughly 30 arcmin2 region of the sky and focuses them onto a small SDD. The SDD detects individual photons, recording their energies with good (few percent) spectral resolution and their detection times to an unprecedented 100 nanoseconds RMS relative to Universal Time. Together, this assemblage provides a high signal-to-noise-ratio photon-counting capability within the 0.2-12 keV X-ray band, perfectly matched to the typical spectra of neutron stars as well as a broad collection of other astrophysical sources.

From NICER's ISS platform, a star-tracker-based pointing system allows the XTI to point to and track celestial targets over nearly a full hemisphere. The pointing system design accommodates the ISS vibration and contamination environments, and enables (together with NICER's GPS-based absolute timing) high-precision pulsar light-curve measurements through ultra-deep exposures spanning the 18-month mission lifetime.

Simulated NICER count rates and spectra can be derived using the WebPIMMS and WebSPEC tools.

A 12-slide overview of NICER science is available here.

More NICER documentation and publications.

If you would like to receive email about NICER developments, please subscribe to the NICER-announce email list.

For those interested in general astronomy/astrophysics information please go to the Education and Public Outreach site.

Artist concept of NICER

Latest News
  • NICER overview published in Nature Astronomy (01 Dec 2017)
    "Searching for a pulse", an overview of NICER by K. Gendreau and Z. Arzoumanian, has been published by Nature Astronomy (Nature Astronomy 1, 895, 2017).
  • NICER ATEL: Observation of Fast X-ray Flares in GX 339-4 (06 Oct 2017)
    NICER observed the black hole binary GX339-4 which is currently in outburst. The average hard color (4-12 / 2-4 keV) is near 0.5 or higher, which is harder than the value for Crab (0.25). These results are consistent with the report that GX339-4 is in a faint black hole hard state (Gandhi et al., Atel 10820).
  • NICER First ATEL: The Hard X-ray transient MAXI J1535-571 (22 Sep 2017)
    NICER has observed the hard X-ray transient MAXI J1535-571 several times from 2017 September 9 through September 20. The source had a NICER count rate ranging from 3,200 to 17,000 counts per second over this interval. NICER detects a set of low-frequency QPOs in a 1:2 frequency ratio, while the time-averaged spectrum shows broadened iron emission and puts constraints on the black hole spin parameter and the inclination of the accretion disk.
  • NICER Featured on "Science in Seconds" (08 Sep 2017)
    NICER was featured on "Science in Seconds" a short introduction to NICER, with NASA Associate Administrator Dr. Thomas Zurbuchen and Dr. Rita Sambruna, NICER program scientist.
  • NICER Press Release: Observations of PSR B1919+21 (02 Aug 2017)
    NICER's science observations have begun. One of the first targets observed was PSR B1919+21, the first pulsar identified 50 years ago by Jocelyn Bell and Anthony Hewish.

[More NICER News]