India’s multi-wavelength space telescope AstroSat had measured the X-ray polarisation of the Crab pulsar (star) in the Taurus constellation, said space agency ISRO on Monday.

“AstroSat accomplished the difficult task of measuring X-ray polarisation of Crab pulsar in the Taurus constellation during 18 months of its study,” said the Indian Space Research Organisaion (ISRO) in a statement here.

ISRO launched its first dedicated space observatory AstroSat on a Polar Satellite Launch Vehicle on September 28, 2015 from its spaceport at Sriharikota in Andhra Pradesh.

“The telescope measured the variations of polarisation as the magetised object (pulsar) spins 30 times per second,” said the statement quoting from a paper published in “Nature Astronomy”.

A pulsar is a rotating neutron star or white dwarf, which emits electromagnetic radiation, and the landmark measurement challenges theories of high energy X-ray emission from pulsars.