Parkes observations for project P898 semester 2015OCTS_BPSR_01

Strader et al. (2015) have identified within the error box of the gamma-ray source 3FGL J1417.5-4402 an extremely interesting optical and X-ray system in a 5.4-day orbit that they interpret as a massive neutron star (NS) with a giant companion currently undergoing accretion. We have discovered at Parkes a radio millisecond pulsar that is clearly the NS in this binary. This indicates that the system is not currently accreting, although there are very likely outflows from the companion. Our early radio results, together with published optical data, suggest a mass ratio of about 6; for a plausible companion mass, this would imply a massive NS, ~2.0 Msun. Here we propose 1.4 GHz timing observations of PSR J1417-4402 in order to precisely measure several characteristics of this system that appears to be unique in the Galactic disk, including constraining its NS mass.