SIMBAD references

A strongly relativistic binary pulsar has recently been discovered with the 64 m Parkes telescope (Burgay et al.). Here we use the measured properties of this binary (masses and orbital characteristics as well as age estimates), and we derive the complete set of constraints imposed on the physical properties of the binary pulsar progenitor right before the second supernova explosion. We find that (1) according to our current understanding of neutron star formation, the helium-rich progenitor of the second neutron star is most likely overflowing its Roche lobe, and (2) the neutron star kick magnitude is constrained in the range 60-1560 km/s, with the most probable value being equal to 150 km/s. While the first conclusion is in agreement with Dewi & van den Heuvel, our upper limit on the kick magnitude is significantly larger than that derived by these authors. We find that the difference arises because Dewi & van den Heuvel inadvertently neglected to consider kicks directed out of the presupernova orbital plane.