Pulsating neutron stars: 4 so far!
1)LCıs may be asymmetric
(skewness)
2)Relatively large pulsed
fractions: 12%-35%
3)All cases: hardness ratio is
max at the pulse maximum: counter-intuitive!
Þ Beaming
effects ? (Cropper et al. 2001)
Þ Phase-dependent cyclotron absorption? 
(Haberl et
al., 2003) Multiple abs. lines
observed in 1E1207.4-5209 are more important
at the light curve trough. The peak of the
total light curve corresponds to the
phase-interval where lines are at their minimum.
(Bignami
et al., 2003, Nature)
(Bignami
et al., 2003, Nature)