Simultaneous Optical and Radio Observations of NP 0532

Abstract

SIMULTANEOUS optical and radio observations of the Crab Nebula pulsar, NP 0532, were obtained at Lick Observatory and Stanford University on March 13 and 15. The exact mechanisms for the radio arid optical emissions are still not clear, but the detection of a time interval (if any) between the optical and radio pulses would be an important test of the various emission theories^1,2. Our data show, after correction for interstellar dispersion, that the optical and radio pulses are emitted simultaneously with a time uncertainty of ± 6 ms resulting almost entirely from the uncertainty in the value of the interstellar dispersion. The measured time delay before correction is accurate to approximately 250 µs.