Time-delay interferometry and clock-noise calibration

The Laser Interferometer Space Antenna is a joint European Space Agency--NASA space mission to detect and study milliherz cosmic gravitational waves. The trajectories followed by its three spacecraft result in unequal- and time-varying arms, requiring use of the time-delay interferometry (TDI) postprocessing technique to cancel the laser phase noises affecting the heterodyne one-way Doppler measurements. Although the second-generation formulation of TDI cancels the laser phase noises when the array is both rotating and ``flexing,'' second-generation TDI combinations for which the phase fluctuations of the onboard ultrastable oscillators can be calibrated out have not appeared yet in the literature. In this article, we present the solution of this problem by generalizing to the realistic LISA trajectory the ultrastable oscillators calibration algorithm derived by Tinto et al. for a static configuration.