tokens: Companion types - main - sequence ( MS ) , neutron star ( NS ) , carbon - oxygen ( or ONeMg ) white dwarf ( CO ) , helium white dwarf ( HE ) , and ultra - light companion or planet ( UL ) - are obtained from Australia Telescope National Facility ( ATNF ) Pulsar Catalog ( http://www.atnf.csiro.au/research/pulsar/psrcat/ ) .