CHIME

Four 20 m × 100 m cylindrical reflectors with 1,024 dual-polarisationpolarimetryMeasuring the polarisation of incoming radiation. It encodes magnetic-field geometry, scattering and emission mechanisms; in the CMB it separates E- and B-mode patterns. feeds and an FX correlatorcorrelatorThe digital system that cross-multiplies the signals from every pair of antennas to form visibilities. Its cost grows with the square of the number of antennas.: a drift-scandrift scanA stationary telescope that lets Earth's rotation sweep the sky through its beam. CHIME has no moving parts and sees every northern declination once a day. telescope with no moving parts that sees the whole northern sky each day at 400–800 MHz. Built for hydrogen intensity mapping21 cm lineThe 1420 MHz hyperfine line of neutral hydrogen (HI). It traces gas in galaxies; redshifted to lower frequencies, its summed brightness over large volumes (intensity mapping) maps large-scale structure without resolving individual galaxies. of baryon acoustic oscillationsbaryon acoustic oscillationsA preferred separation of about 150 Mpc (comoving) in the galaxy distribution, imprinted by sound waves in the early Universe. Measuring it at many redshifts traces the expansion history like a standard ruler. at z ≈ 0.8–2.5, it has also become the most productive fast radio burstfast radio burstA millisecond radio pulse of extragalactic origin. Dispersion by free electrons along the path delays low frequencies, measuring the column of ionised gas between us and the source. Some repeat; the sources are thought to be mainly magnetars. detector, with thousands found by CHIME/FRB, and times 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. daily.

Operator

CHIME collaboration

Site

Penticton, British Columbia

Passband

400 MHz – 800 MHz

First light

September 2017