Pulsars are rotating neutron stars , sweeping the emission regions from the magnetic poles across our line of sight .
Isolated neutron stars lose angular momentum through dipole radiation and ( possibly ) particle winds , hence they slow down extremely steadily , making them amongst the most reliable timing sources available .
However , it is well known that younger pulsars can suffer glitches , when they suddenly deviate from their stable rotation period .
On 2000 January 16 ( MJD 51559 ) the rate of pulsation from the Vela pulsar ( B0833-45 ) showed such a fractional period change of 3.1 \times 10 ^ { -6 } , the largest recorded for this pulsar .
The glitch was detected and reported by the Hobart radio telescope .
The speedy announcement allowed the X-ray telescope , Chandra , and others , to make Target of Opportunity observations .
The data placed an upper limit of 40 seconds for the transition time from the original to the new period .
Four relaxation timescales are found , which are believed to be due to the variable coupling between the crust and the interior fluid .
One is very short , about 60 seconds ; the others have been previously reported and are 0.56 , 3.33 and 19.1 days in length .