Discovery of short-period binary millisecond pulsars in four globular clusters

We report the discovery, using the Parkes radio telescope, of binary millis econd pulsars in four clusters for which no associated pulsars were previou sly known. The four pulsars have pulse periods lying between 3 and 6 ms. Al l are in circular orbits with low-mass companions and have orbital periods of a few days or less. One is in a 1.7 hr orbit with a companion of planeta ry mass. Another is eclipsed by a wind from its companion for 40% of the bi nary period despite being in a relatively wide orbit. These discoveries res ult from the use of improved technologies and prove that many millisecond p ulsars remain to be found in globular clusters.