Crab pulsar photometry and the signature of free precession
Vidrih, S.; Carramiñana, A.; Čadež, A.; Galičič, M.
Mexico, Slovenia
Abstract
Optical photometry for the pulsar PSR 0531+21 has been extended with new observations that strengthen evidence for a previously observed 60 s periodicity. This period is found to be increasing with time at approximately the same rate as the rotational period of the pulsar. The observed period and its time dependence fit a simple free precession model.