Crab Nebula was discovered 1731 by British amateur astronomer John Bevis and independently rediscovered in 1758 by Charles Messier. The Crab Nebula, Messier 1 (M1, NGC 1952, SN 1054), is the most famous and conspicuous known supernova remnant, the expanding cloud of gas created in the explosion of a star as supernova which was observed in the year 1054 AD. It shines as a nebula of magnitude 8.4 near the southern "horn" of Taurus.

The Crab nebula and the pulsar at the center of this nebula are among the most important objects of modern astrophysics (Hester 2008). The Crab pulsar was observed for a first time in 1968 and represents a neutron star 28–30 kilometers across with a spin rate of 30.2 times per second, which emits pulses of radiation from gamma rays to radio wave.

The Crab Nebula is an extreme particle accelerator boosting the energy of electrons up to a few PeV (1015 eV), close to the maximum energy allowed by theory. The recent investigations reveal of ultra-high energy gamma-ray signal from the Crab Nebula up to 300 TeV. The Crab Nebula is unique, but not an archetypical representative of PWN (Pulsar Wind Nebula). Its pulsar is much more powerful than the pulsars of most of other PWNe and, surprisingly, the Crab Nebula is unusually compact. Crab Nebula is a rather inefficient gamma-ray emitter. The low IC (inverse Compton) radiation efficiency is compensated by the vast rotational power of the Crab pulsar. Therefore, despite the low efficiency, the Crab Nebula remains a very strong gamma-ray source. (Khangulyan et al., 2020)