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The Crab Pulsar was the first pulsar for which the spin-down limit was broken using several months of data of the LIGO observatory. Most pulsars do not rotate at constant rotation frequency, but can be observed to slow down at a very slow rate (3.7 × 10 −10 Hz/s in case of the Crab).
The Crab Nebula, and the Crab Pulsar within it, is an intense space X-ray source. It is used as a standard candle in the calibration procedure of X-ray instruments in space. However, because of the Crab Nebula's variable intensity at different X-ray energies, conversion of the Crab to another units depends on the X-ray energy range of interest.
The Crab Nebula is a pulsar wind nebula associated with the 1054 supernova.It is located about 6,500 light-years from the Earth. [1]A near-Earth supernova is an explosion resulting from the death of a star that occurs close enough to the Earth (roughly less than 10 to 300 parsecs (pc) [30 to 1000 light-years] away [2]) to have noticeable effects on Earth's biosphere.
An optical pulsar is a pulsar which can be detected in the visible spectrum. There are very few of these known: the Crab Pulsar was detected by stroboscopic techniques in 1969, [ 1 ] [ 2 ] shortly after its discovery in radio waves, at the Steward Observatory .
The Crab Nebula (catalogue designations M1, NGC 1952, Taurus A) is a supernova remnant and pulsar wind nebula in the constellation of Taurus. The common name comes from a drawing that somewhat resembled a crab with arms produced by William Parsons, 3rd Earl of Rosse , in 1842 or 1843 using a 36-inch (91 cm) telescope . [ 6 ]
Pulsar wind nebulae evolve through various phases. [2] [5] New pulsar wind nebulae appear soon after a pulsar's creation, and typically sit inside a supernova remnant, for example the Crab Nebula, [6] or the nebula within the large Vela Supernova Remnant. [7] As the pulsar wind nebula ages, the supernova remnant dissipates and disappears.
The 42 ft (12.8 m) dish is mainly used to observe pulsars, and continually monitors the Crab Pulsar. [ 43 ] When the 42 ft was installed, a smaller dish, the "7 m" (actually 6.4 m, or 21 ft, in diameter) was installed and is used for undergraduate teaching.
The_Crab_Nebula_NASA.ogv (Ogg multiplexed audio/video file, Theora/Vorbis, length 3 min 42 s, 640 × 360 pixels, 558 kbps overall, file size: 14.78 MB) This is a file from the Wikimedia Commons . Information from its description page there is shown below.