NuSTAR

The first focusing hard X-rayhard X-raysThe higher-energy end of the X-ray band, conventionally above about 10 keV; soft X-rays are below about 2 keV. Hard X-rays penetrate absorbing gas, so they reveal obscured black holes. telescope in orbit: two co-aligned grazing-incidencegrazing-incidence opticsX-rays reflect only at angles of a degree or less, so X-ray telescopes use nested shells of paraboloid and hyperboloid mirrors seen almost edge-on (the Wolter-I design). More shells add effective area; figure accuracy sets the PSF. modules with depth-graded multilayer coatingsmultilayer opticsGrazing-incidence mirrors coated with hundreds of alternating thin layers whose spacing varies with depth, so they reflect hard X-rays by Bragg reflection. What lets NuSTAR focus up to 79 keV., on a deployable mast that sets a 10 m focal length, image 3–79 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. onto CdZnTe detectors at 18″ FWHM. Sensitivity and angular and spectral resolutionspectral resolutionHow finely a spectrograph separates wavelengths, quoted as resolving power R = λ/Δλ (optical, infrared) or energy resolution ΔE in eV (X-rays). R ~ 100 measures redshifts of faint galaxies; R ~ 100,000 measures stellar radial velocities. improve on earlier hard X-ray missions by factors of 10 to 100: obscured AGN, black-hole spin, ⁴⁴Ti in supernova remnantssupernova remnantThe expanding debris and shocked interstellar gas left by a supernova, bright in X-rays for thousands of years. X-ray spectra give its temperature and the elements the explosion made. and cyclotron lines of accreting neutron starsneutron starThe collapsed core of a massive star: about 1.4 solar masses in a 12 km radius, at above nuclear density. Its mass–radius relation tests the equation of state of dense matter..

Operator

NASA

Orbit

Low Earth orbit

Aperture

Two 10 m focal-length mirror modules on a mast

Passband

3 keV – 79 keV

Launch

13 June 2012