LIGO at the threshold of science operations

LIGO held its first science run during the two and one-half week period from 23 August to 09 September 2002. The strain sensitivity of the interferometers during this observational period was h(f) ∼ 10−20 Hz− 1 2 at f ∼ 300Hz. The useful instrumental bandwidth spanned the decade 100Hz ∼< f ∼< 1000Hz. During the 17-day period, the three km-scale LIGO interferometers (4km and 2km in WA and 4km in LA) and the 600m GEO interferometer (outside Hanover, Germany) operated as a network of detectors for part of the time. The LIGO Scientific Collaboration are presently analyzing the first data run (S1) for a number of classes of sources of gravitational radiation. Working groups within the collaboration are performing searches for signatures coming from four classes of gravitational wave (GW) sources. These include: (i) continuous wave sources, (GW counterparts to EM pulsars); (ii) burst or transient sources, such as GW emissions from SNe; (iii) inspiral and coalescence of compact binary systems; (iv) a stochastic gravitational wave background. The emphasis in this first science run will be develop the analysis techniques and software pipelines that will be used to analyze data continuously during periods of extended observation in future science runs. At the same time, the S1 data quality are such that it should be possible to provide improved direct observational limits on gravitational radiation with these fundamentally new instruments.