Initially identified as a new X-ray transient by ESA's INTEGRAL satellite, IGR J00291+5934 was found in RXTE observations to be a 599 Hz millisecond pulsar. Subsequent observations revealed a 2.46 hr orbit, making the source very similar to the original millisecond X-ray pulsar, SAX J1808.4-3658.

Read the paper (ApJ 622, 45L 2005)
INTEGRAL team discovery paper (Shaw et al. 2005, A&A, 432, L13)
U. Southampton press release Feb 16^th 2005
New Scientist breaking news Feb 22^nd 2005

Labels: 2004, pulsars