Einstein Probe

Einstein Probe artist impression
Names	Aiyinsitan Tanzhen
Mission type	Space observatory
Operator	CAS,ESA
COSPAR ID	2024-007A
SATCATno.	58753
Website	ep.bao.ac.cn/ep/
Mission duration	3 years (planned) 2 years, 1 month and 7 days (ongoing)
Spacecraft properties
Spacecraft	Einstein Probe
Bus	Phoenix-Eye-2
Manufacturer	CAS
Launch mass	1,450 kg (3,200 lb)[1]
Dimensions	3 × 3.4 m (9.8 × 11.2 ft)
Start of mission
Launch date	9 January 2024, 07:02 UTC[2]
Rocket	Long March 2C[2]
Launch site	Xichang LC-3
Contractor	CASC
Orbital parameters
Reference system	Geocentric orbit
Regime	Low Earth orbit
Perigee altitude	581 km
Apogee altitude	596 km
Inclination	29°
Period	96 minutes
Instruments
Wide-field X-ray Telescope (WXT) Follow-up X-ray Telescope (FXT)
Einstein Probe Logo

TheEinstein Probe (EP) is anX-rayspace telescope mission byChinese Academy of Sciences (CAS) in partnership withEuropean Space Agency (ESA) and theMax Planck Institute for Extraterrestrial Physics (MPE) dedicated to time-domainhigh-energy astrophysics.^[3][1] The primary goals are "to discover high-energy transients and monitor variable objects".^[4] The telescope was launched by aLong March 2C rocket from theXichang Satellite Launch Centre in China, on 9 January 2024, at 07:03UTC.^[5]

The primary science objectives are:^[6]

1. Identify inactiveblack holes to study how matter is precipitated there by detecting the transient events that take the form of X-ray flares;
2. Detect the electromagnetic counterpart of events triggering gravitational waves such as themerger of neutron stars which will be discovered by the next generation of gravitational wave detectors;
3. Carry out permanent monitoring of the entire sky to detect the various transient phenomena and carry out measurements of known variable X-ray sources.

Einstein Probe carries 2 scientific instruments: the Wide-field X-ray Telescope (WXT), and the Follow-up X-ray Telescope (FXT).^[7] Both telescopes utilize X-ray focusing optics.

• Wide-field X-ray Telescope (WXT): WXT has a new optics design, called "lobster-eye", that has wider field of view.^[1][7] "Lobster-eye" optics was first tested by theLobster Eye Imager for Astronomy (LEIA) mission, launched in 2022.^[1][8][9] WXT consists of 12lobster-eye optics sensor modules, together creating a very large instantaneousfield-of-view of 3600square degrees. The nominal detection bandpass of WXT is 0.5–4.0keV. Each module weighs 17 kg and has an electrical power consumption of just under 13 W. With the peripherals, the entire telescope weighs 251 kg and has a power consumption of 315 W.

• Follow-up X-ray Telescope (FXT): FXT has optics adopted fromeROSITA. "The mirror module consists of 54 nestedWolter mirrors with a focal length of 1600 mm and an effective area of greater than 300 cm² at 1.5keV."^[7]

The probe weights 1450 kg and is3 × 3.4 metres.^[1]

The Einstein Probe was launched on 9 January 2024, at 07:03UTC by aLong March 2C rocket from theXichang Satellite Launch Centre in China, and successfully placed inlow Earth orbit at an altitude of 600 km^[2] and an inclination of 29°, giving an orbital period of 96 minutes.^[10]

CAS reported that EP "performs as expected in the first month".^[11] The probe detected fastX-ray transient EP240315a,^[12] andbright X-ray flares EP240305a^[13] and EPW20240219aa.^[14]

On 15 March 2024, the Einstein Probe detected EP240315a, a softX-ray burst from 12.5 billion light-years away, lasting over 17 minutes—the longest duration observed from such an ancient explosion. Linked togamma-ray burstGRB 240315C, this event showed a six-minute delay between X-rays and gamma rays, never observed before. ESA notes that these findings challenge existing gamma-ray burst models.^[15][16][17]

The probe observed an X-ray outburst from EP J0052, arare binary system of aBe star and awhite dwarf (BeWD). After this discovery, several other space telescopes observed the system, including NASA'sSwift andNICER, and ESA'sXMM-Newton. XMM-Newton did not find the outburst 18 days after the EP's observations.^[18][19]

• Timeline of artificial satellites and space probes
• List of things named after Albert Einstein
• X-ray astronomy
• List of space telescopes#X-ray

• Yuan, Weimin; Zhang, Chen; Chen, Yong; Ling, Zhixing (2022). "The Einstein Probe Mission".Handbook of X-ray and Gamma-ray Astrophysics. pp. 1–30.arXiv:2209.09763.doi:10.1007/978-981-16-4544-0_151-1.ISBN 978-981-16-4544-0.

Wikimedia Commons has media related toEinstein Probe.

• Official website atNAOC,CAS.Archived January 2, 2022, at theWayback Machine
• Einstein Probe at ESA.int
• Einstein Probe at MPE.MPG.de

• Space telescopes
• X-ray telescopes
• Chinese Academy of Sciences
• Chinese telescopes
• January 2024 in China
• Spacecraft launched in 2024
• 2024 in spaceflight

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