Einstein Probe (EP)

Follow-up X-ray Telescope (FXT) official website: (http://epfxt.ihep.ac.cn/)

The Einstein Probe (EP) Mission

The Einstein Probe (EP) is a mission of the Chinese Academy of Sciences (CAS) dedicated to time-domain high-energy astrophysics. Its primary goals are to discover high-energy transients and monitor variable objects. To achieve this, EP employs a very large instantaneous field-of-view (3600 square degrees), along with moderate spatial resolution (FWHM ~5 arcmin) and energy resolution.  Its wide-field imaging capability is achieved by using established technology of novel lobster-eye optics, thereby offering unprecedentedly high sensitivity and large Grasp, which would supersede previous and existing X-ray all-sky monitors. To complement this powerful capability to discover and monitor sources over a wide area, EP also carries a conventional X-ray focusing telescope with a larger effective area to perform follow-up characterization and precise localization of newly-discovered transients. Public transient alerts will be issued rapidly to trigger multi-wavelength follow-up observations from the world-wide community. The satellite has a weight of ～1450 kg and average power of ～1212 W in total. In the normal survey mode, during one orbit of 97 minutes three fields will be observed on the night-side of the sky with a ~20 min pointing each. Over three orbits almost the entire night sky will be sampled, with cadences ranging from several to a few ten revisits per day depending on the sky location. The mission was launched on Jan. 9th, 2024.

Payloads and Developers

Wide-field X-ray Telescope (WXT)

Role: Utilizing groundbreaking lobster-eye bionic optical technology, it achieves an enormous field of view exceeding 3,600 square degrees, conducting "cinematic" monitoring of the entire sky every second to efficiently capture transient X-ray sources.

Developing Institutions: Led by the Innovation Academy for Microsatellites (IAM) of CAS, jointly developed with the National Astronomical Observatories (NAOC) of CAS and domestic and international partners.

Follow-up X-ray Telescope (FXT) 

Role: As a high-precision follow-up observation payload, it employs a Wolter-I grazing-incidence focusing design to conduct rapid precision measurements and deep observations of transient sources discovered by WXT, providing sub-arcsecond localization accuracy and detailed spectral analysis to reveal the physical properties and evolution mechanisms of celestial objects.

Developing Institutions: Led by the State Key Laboratory of Particle Astrophysics (SKLPA) of Institute of High Energy Physics (IHEP) of CAS, developed in close collaboration with international institutions such as the European Space Agency (ESA) and the Max Planck Institute for Extraterrestrial Physics (MPE).