Sengar et al. report the discovery and timing of two pulsars from a sample of four circularly polarized sources identified in radio continuum images taken as part of the ASKAP Variables and Slow Transients (VAST) survey. Observations with Murriyang, CSIRO’s Parkes radio telescope, confirmed both sources as normal pulsars with high dispersion measures. PSR J1646-4451 has a spin period of 217 ms and a dispersion measure (DM) of 928 cm^-3 pc, while PSR J1837−0616 exhibits a spin period of 118 ms and a DM of 793 cm^-3 pc. These pulsars show extreme pulse broadening due to scattering, with measured scattering timescales of 290 ms and 343 ms at observing frequencies of 1.8 GHz and 1.9 GHz, respectively. These measurements imply extrapolated scattering timescales at 1 GHz of 2479 ms and 2154 ms, placing them among the most heavily scattered pulsars known to date. These findings underscore the potential of using circular polarization in radio continuum images as a tool for identifying highly scattered pulsars. Future wide-field radio continuum surveys are poised to uncover a broader population of extreme pulsars particularly those that are heavily scattered at 1.4 GHz, intrinsically faint, or residing in binaries — offering valuable insights into both pulsar demographics and the complex structure of the interstellar medium.

The image above shows ASKAP radio continuum images of the field centered on PSR J1837-0616 at 888 MHz. The Stokes I image (total intensity, at left) shows the total intensity emission, revealing extended Galactic structure and diffuse background emission, while the Stokes V image (circular polarisation, in the middle) displays the circularly polarized intensity. The white square marks the known positions of the pulsar. The panels on the right show zoomed-in views centered on the pulsar positions in both Stokes I and V, with the pulsar location indicated by white crosshairs. These images have been corrected for the ASKAP primary beam response, and the color bars denote the flux density scales in µJy/beam. The cyan ellipse indicates the HII region WISE G025.867+00.118.