Intermittent pulsations in HETE J1900.1-2455
The Energizer Bunny of the accretion-powered millisecond pulsars is unusual not just because it has been active for more than a year since its discovery in June 2005 ("he's still goin'!"). Pulsations were only detected in the first few months of the outburst; since then, the source has been indistinguishable from an ordinary low-accretion rate LMXB. In all the other millisecond X-ray pulsars (and, for that matter, all other accretion-powered pulsars) pulsations are always present when the source is active. Our paper on the properties of the pulsations is out now at astro-ph/0609693.