SATLASX-ray · Space
NICER
Neutron star Interior Composition Explorer
PausedPaused since 17 June 2025.
Science observations have been suspended since 17 June 2025 after a pointing-actuator anomaly; the team is returning the instrument to its stowed configuration ahead of disposal. A 2023 light leak had been patched on a spacewalk in January 2025.
An X-ray timingX-ray timingMeasuring photon arrival times precisely enough to follow pulsations and variability. Modelling the pulse shape of hotspots on a rotating neutron star, bent by gravity, constrains its mass and radius. instrument on the ISS: 56 concentrator optics with silicon drift detectors covering 0.2–12 keVelectronvoltThe energy an electron gains across 1 volt, 1.602 × 10⁻¹⁹ J. High-energy astronomy labels photons by energy: optical light is about 1.7–3.1 eV, X-rays 0.1–100 keV, gamma rays from about 100 keV to beyond 100 TeV. A 1 keV photon has wavelength 1.24 nm., time-tagging photons to about 100 ns. Pulse-profile modelling of hotspots on millisecond pulsarspulsarA rotating, magnetised neutron star whose beamed emission sweeps past Earth once per turn. Millisecond pulsars, spun up by accretion, keep time to tens of nanoseconds over decades. such as PSR J0030+0451 and PSR J0740+6620 has measured neutron-star radii to about ±1 km, constraining the dense-matter equation of state.
- Operator
- NASA
- Orbit
- International Space Station
- Passband
- 0.2 keV – 12 keV
- Launch
- 3 June 2017
- Science suspended
- 17 June 2025
Passband
Sky coverage
Pointed observationspointed observationObserving chosen targets, usually selected by peer review in annual proposal cycles, as opposed to surveying the sky systematically. Gives depth on few objects; the total area observed stays small., constrained by the ISS orbit and Sun angle; non-imaging, with a field of viewfield of viewThe patch of sky an instrument images at once, in square degrees for wide-field cameras or in steradians (sr) for all-sky monitors; 4π sr is the whole sky. of about 30 arcmin².
Archives
Sources
Verified 15 November 2026.