Abstract

Wereport on an all-sky search with the LIGO detectors forperiodic gravitational waves in the frequency range 50–1100 Hz and withthe frequency's time derivative in the range -5×10-9–0 Hz s-1. Data fromthe first eight months of the fifth LIGO science run(S5) have been used in this search, which is basedon a semicoherent method (PowerFlux) of summing strain power. Observingno evidence of periodic gravitational radiation, we report 95% confidence-levelupper limits on radiation emitted by any unknown isolated rotatingneutron stars within the search range. Strain limits below 10-24are obtained over a 200-Hz band, and the sensitivity improvementover previous searches increases the spatial volume sampled by anaverage factor of about 100 over the entire search band.For a neutron star with nominal equatorial ellipticity of 10-6,the search is sensitive to distances as great as 500 pc.