SIMBAD references

Based on the free precession model of the isolated pulsar PSR B1828-11, Link Epstein (2001) showed that the observed pulse durations require the radio beam to have a non-standard shape: the beam duration is larger for beam sweeps farthest from the dipole axis. In their analysis they assumed that the actual precession period is ≃500d. Recent theoretical studies suggested that the actual precession period might be ≃1000d as seen in observations (Rezania, 2003A&A...399..653R; Wasserman 2003, preprint, astro-ph/0208378). In this paper, in a good agreement with the observed data (Stairs et al., 2000Natur.406..484S), we model the changes of the pulse shape in a precession cycle with period 1000d and find that the variation of the pulse duration follows from a standard beam pattern in each cycle.