Published fits give opposite orbital-change signs for J1544+4937 in a distance-free clock test

We test 66 non-cluster binary pulsars in ATNF 2.9.0 with the difference between spin and orbital fractional period changes. Under nonnegative intrinsic spin-down, a positive difference requires intrinsic orbital expansion. Five fits retain a positive value throughout a three-error input region. A source check reduces the stored J1728-4608 orbital derivative by a factor of 100; its flag remains. For J1544+4937, the catalog ELL1 fit gives a positive difference of 6.20e-17 inverse seconds. A published BTX fit to the same observations gives a negative local value of -1.78e-15 inverse seconds. The fits describe different slopes in a variable orbit. Thus the catalog flag does not establish steady expansion. Separate NRT and NANOGrav fits for J0636+5128 both give positive orbital changes but different values. These are known interacting binaries, not new objects or signals. Timing noise, model choice, missing covariance and mixed catalog epochs limit physical claims. Code, frozen inputs, source checks, hashes, figure and offline steps are included.

astronomy · pulsar timing · ATNF · orbital variability · J1544+4937 · J1728-4608 · catalog validation · acceleration cancellation