A&A 366, 930-934 (2001)
Crab pulsar photometry and the signature of free precessionA. Cadez1, S. Vidrih1, M. Galicic1 and A. Carramiñana1
1 Department of Physics, FMF University in Ljubljana, Jadranska 19, 1000 Ljubljana, Slovenia I.N.A.O.E., Luis Enrique Erro 1, Tonantzintla, Puebla 72840, Mexico
(Received 3 July 2000 / Accepted 16 November 2000 )
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.
Key words: stars: neutron -- pulsars: individual: PSR 0531+21 -- rotation -- oscillations
Offprint request: A. Cadez, email@example.com
© ESO 2001