A search for submillisecond pulsars

We have conducted a search of 19 southern Galactic globular clusters for su bmillisecond pulsars at 660 MHz with the Parkes 64 m radio telescope. To mi nimize dispersion smearing we used the CPSR baseband recorder, which sample s the 20 MHz observing band at the Nyquist rate. By possessing a complete d escription of the signal we could synthesize an optimal filter bank in soft ware, and in the case of globular clusters of known dispersion measure, muc h of the dispersion could be removed using coherent techniques. This allowe d for very high time resolution (25.6 ks in most cases), making our searche s in general sensitive to submillisecond pulsars with flux densities greate r than about 3 mJy at 50 cm. No new pulsars were discovered, placing import ant constraints on the proportion of pulsars with very short spin periods i n these clusters.