Calibration of the dual-recycled GEO 600 detector for the S3 science run

The GEO 600 interferometric gravitational detector took part in an extended coincident science run of the LIGO Scientific Collaboration (S3) that started in November 2003. GEO had recently been upgraded to be the first large-scale fully suspended dual-recycled interferometer in the world and was in the early stages of commissioning in this configuration. In order to prepare the GEO 600 data for the possible extraction of science results and for exchange between analysis groups of the gravitational wave community, the data need to be accurately calibrated. An online, time-domain calibration scheme that was initially developed to calibrate the power-recycled GEO 600 configuration, has been extended to cover the significantly more complicated case of calibrating the dual-recycled interferometer, where the optical response of the instrument is much more difficult to measure and calibrate out online. This report presents an overview of this calibration scheme as it was applied to calibrating the GEO S3 science run data. In addition, results of the calibration process are presented together with some discussion of the accuracy achieved