We perform a wide parameter-space search for continuous gravitational waves over the whole sky and over a large range of values of the frequency and the first spin-down parameter. Our search method is based on the Hough transform, which is a semicoherent, computationally efficient, and robust pattern recognition technique. We apply this technique to data from the second science run of the LIGO detectors and our final results are all-sky upper limits on the strength of gravitational waves emitted by unknown isolated spinning neutron stars on a set of narrow frequency bands in the range 200–400 Hz. The best upper limit on the gravitational-wave strain amplitude that we obtain in this frequency range is 4.43×10−23.
Abbott, B., et al. “First All-Sky Upper Limits from LIGO on the Strength of Periodic Gravitational Waves Using the Hough Transform.” Physical Review D, vol. 72, no. 10, American Physical Society, Nov. 2005, p. 102004, doi:10.1103/PhysRevD.72.102004.
Physical Review D