Kerr et al. report the discovery of four millisecond pulsars (MSPs) found in searches of 80 γ-ray sources conducted between 2015 and 2017 using the Murriyang radio telescope at the Parkes Observatory. They provide an overview of the survey and focus on results from a follow-up pulsar timing campaign. Using data from the Fermi Large Area Telescope, γ-ray pulsations were detected from all four pulsars. By combining radio and γ-ray observations, improved timing solutions were achieved. The authors also present flux density distributions and flux-calibrated, phase-aligned radio and γ-ray pulse profiles. Some of these pulsars may be suitable for inclusion in radio pulsar timing array experiments. PSRs J0646-5455, J1803-4719, and J2045-6837 are in nearly circular white dwarf binaries, with residual eccentricities proportional to their binary periods. PSR J1833-3840 is a black widow pulsar with the longest known orbital period (Pb = 0.9 days) and a notably soft radio spectrum. PSR J0646-5455, with its strong Vela-like γ-ray profile, is a good candidate for the γ-ray Pulsar Timing Array (GPTA), despite possibly being one of the lowest-efficiency γ-ray MSPs known. In fact, all four MSPs display lower-than-average γ-ray efficiency, suggesting a possible detection bias in earlier searches. Retrospective evaluation of the survey shows that while only four MSPs were directly discovered, further pulsar detections in 19 additional targets bring the effective survey success rate to a strong 30%.

The figure displays the measured flux densities for each UWL epoch, with preference given to fold-mode measurements where available for their higher precision. The data points are color-coded by frequency sub-band: orange for 1.0 GHz, green for 1.7 GHz, and blue for 3.3 GHz.The dashed line indicates the best-fit power-law flux model to the mean flux densities, with the black stars using this model to estimate the flux density at the canonical 1.4 GHz. The black squares give the mean flux density for the fold-mode data only—i.e. just for latter epochs—-and are shown here for comparison because these observations are used to estimate the timing precision.