In our conversation that's the one thing he got excited about. I'm not even sure what's possible so I can only assume he's learning about it also as he's reading it off.
That's what led us to the assumption it was a supernova Survivor
According to this source, the planet has 0.39 solar masses, so it's a pretty heavy thing!I found this (from June) fairly easily though and the numbers are extremely similar.
http://adsabs.harvard.edu/abs/2018ATsir1642....1R

Well, general relativity for this situation can account for about 0.1 arcseconds per orbit. Things like tidal dissipation, frame dragging, etc can modify that slightly, but 44 degrees per orbit is, um, nuts. That would require a very close orbit around a black hole... (and being close enough to a stellar mass black hole to get that much precession would instantly destroy the planet).


Those numbers look good.

The mass of a pulsar (or neutron star in general) is usually between about 1.4 and 3 solar masses. If the orbital period is 20.2 years with semimajor axis of 8.4AU, this means the pulsar mass must be about 1.45 solar masses (by Kepler's Third Law).
There we go! Found it near the bottom of the page:
The planet of the pulsar B0525+21 has orbital period P2 = 20.2 yr, orbital semi-major axis a2 = 8.4 AU, eccentricity e2 = 0.96, and mass m2sini = 0.5M⊕. Additionally, the precession of the planet's line of apses has been measured, and it is dφ = -0.77 rad/period. A high eccentricity may indicate that this planet has survived a supernova explosion.


As I said here,
according to the source named by Gnargenox, the mass of the planet is 0.39 solar masses, not 0.5 Earth masses.

The limit for cold non-rotating neutron star is 2.16 solar masses, but they can be a bit heavier with spin. 2.5 solar masses could be possible. But in this case, if the reported planet mass is 0.5 Earth masses (from the IAU conference page), and the orbital period is 20.2 years with 8.4AU semimajor axis, then the mass has to be 1.45 solar masses (with whatever error bars, since there are no uncertainties for these figures.)
Why is this differentiation made, rotating and non-rotating neutron stars? There are almost certainly no non-rotating neutron stars in the universe!