SVOM

A Chinese–French gamma-ray burstgamma-ray burstA flash of gamma rays lasting milliseconds to minutes, followed by a fading afterglow at longer wavelengths. Long bursts come from collapsing massive stars; short ones from neutron-star mergers. mission (CNSA, CAS and CNES). ECLAIRs (coded-maskcoded-mask imagingImaging hard X-rays and gamma rays, which cannot be focused, by placing a patterned mask above a position-sensitive detector. Each source casts a shifted shadow of the pattern; deconvolution recovers the sky over a wide field at modest resolution., 4–250 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., 89° × 89° field) and the GRM (scintillatorsscintillatorA crystal (NaI, BGO, CsI) that emits a flash of visible light when a gamma ray deposits energy in it, read by photomultipliers or photodiodes. Simple, large and omnidirectional, so used for burst monitors., 15 keV–5 MeV) detect bursts; the platform then slews so the MXT (micro-pore optics, 0.2–10 keV) and the VT (450–650 and 650–1000 nm channels) observe the afterglowafterglowThe fading X-ray, optical and radio emission from the shock a gamma-ray burst's jet drives into its surroundings, lasting hours to months. Localising it gives the host galaxy and redshift. within minutes. ECLAIRs' low 4 keV threshold favours soft, X-ray-rich and high-redshiftredshiftz = λ_observed/λ_emitted − 1, the stretching of light by cosmic expansion (or by recession). For distant sources it stands in for distance and look-back time: z ≈ 1 is about 8 Gyr ago, z ≈ 10 about 13.3 Gyr. bursts.

Operator

CNSA, CNES

Orbit

Low Earth orbit

ECLAIRs

4 keV – 250 keV

GRM

15 keV – 5 MeV

MXT

0.2 keV – 10 keV

VT

450 nm – 1000 nm

Launch

22 June 2024