It's deja vu, all over again
Our recent discovery of 552 Hz burst oscillations in the well-known binary EXO 0748-676 was fairly unremarkable, except perhaps for the extreme rarity of the oscillations (detected in only 2 of ~160 bursts observed by RXTE). However, oscillations had already been detected in this source back in 2004, at 45 Hz. The 552 Hz signal is much stronger, recommending it as the neutron star spin; unfortunately, the Doppler broadening that would be expected by such a spin means that the narrow spectral features previously identified as arising from the neutron star surface, could not have. Our paper has now (Feb '10) been accepted by ApJL.
Read the paper (arXiv.org/0910.5546)