A Search for Optical Pulsations from Two Young Southern Pulsars

We report on high-speed optical photometry of the radio positions of two young rotation-powered pulsars. No pulsations were detected from the optical counterpart proposed by Caraveo et al. (1994) for PSR B1509–58, with a 2σ upper limit on the pulsed fraction of < 12%, significantly lower than that measured in the five known optical pulsars. Given its low pulsed fraction, high optical luminosity, and significant (8%) chance coincidence probability, we suggest that this candidate is not associated with the pulsar. We also find that the stillunidentified optical counterpart of PSR B1706–44 has R ∼> 18 and lies within 3 arcsec of an R = 16.6 star. Subject headings: pulsars: individual (PSR B1509–58) — pulsars: individual (PSR B1706–44) — stars: neutron