Chandra

Four nested pairs of Wolter-Igrazing-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. grazing-incidence mirrors with a 10 m focal length give a PSFpoint-spread functionThe image a system makes of a point source. Its width (often quoted as FWHM, or half-energy width for X-ray optics) sets the effective resolution; its shape matters for photometry, deblending and weak-lensing shape measurement. half-power diameter below 0.5″, still the sharpest X-ray imaging flown. ACIS (CCDCCDCharge-coupled device: a silicon pixel array that stores photo-electrons and shifts them to a readout amplifier. The workhorse optical detector; in X-rays, each photon's charge also measures its energy. imaging spectroscopy) and HRC (microchannel plates), with the HETG and LETG transmission gratings, cover 0.1–10 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.: AGN and jets, 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., cluster gas and X-ray binaries.

Operator

NASA, SAO

Orbit

Highly elliptical Earth orbit

Aperture

1.2 m nested grazing-incidence mirrors

Passband

0.1 keV – 10 keV

Launch

23 July 1999