Einstein Probe

Einstein Probe artist impression
Names	Aiyinsitan Tanzhen
Mission type	Space observatory
Operator	CAS, ESA
COSPAR ID	2024-007A
SATCAT no.	58753
Website	ep.bao.ac.cn/ep/
Mission duration	3 years (planned) 7 months and 28 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

The Einstein Probe (EP) is an X-ray space telescope mission by Chinese Academy of Sciences (CAS) in partnership with European Space Agency (ESA) and the Max Planck Institute for Extraterrestrial Physics (MPE) dedicated to time-domain high-energy astrophysics.^[3][4] The primary goals are "to discover high-energy transients and monitor variable objects".^[5] The telescope was launched by a Long March 2C rocket from the Xichang Satellite Launch Centre in China, on 9 January 2024, at 07:03 UTC.^[6]

The primary science objectives are:^[7]

1. Identify inactive black 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 the merger 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).^[8] 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.^[4][8] "Lobster-eye" optics was first tested by the Lobster Eye Imager for Astronomy (LEIA) mission, launched in 2022.^[4][9][10] WXT consists of 12 Lobster-eye optics sensor modules, together creating a very large instantaneous field-of-view of 3600 square degrees. The nominal detection bandpass of WXT is 0.5~4.0 keV. 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 from eROSITA, "the mirror module consists of 54 nested Wolter mirrors with a focal length of 1600 mm and an effective area of greater than 300 cm2 at 1.5 keV."^[8]

The probe weights 1450 kg and is 3-by-3.4 metres.^[4]

Einstein Probe was launched on 9 January 2024, at 07:03 UTC by a Long March 2C rocket from the Xichang Satellite Launch Centre in China, and successfully placed in low Earth orbit at an altitude of 600 km^[2] and an inclination of 29 degrees, giving an orbital period of 96 minutes.^[11]

CAS reported that EP "performs as expected in the first month".^[12] The probe detected fast X-ray transient EP240315a,^[13] and bright X-ray flares EP240305a^[14] and EPW20240219aa.^[15]

• 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 to Einstein Probe.

• Official website at NAOC, CAS. Archived January 2, 2022, at the Wayback Machine
• Einstein Probe at ESA.int
• Einstein Probe at MPE.MPG.de