  Data collected by the GEO600 and LIGO interferometric gravitational wave
detectors during their first observational science run were searched for
continuous gravitational waves from the pulsar J1939+2134 at twice its rotation
frequency. Two independent analysis methods were used and are demonstrated in
this paper: a frequency domain method and a time domain method. Both achieve
consistent null results, placing new upper limits on the strength of the
pulsar's gravitational wave emission. A model emission mechanism is used to
interpret the limits as a constraint on the pulsar's equatorial ellipticity.
