The paper discusses the problematic of data timing in the framework of the space astrometry mission Gaia. For various reasons related both to astrometry and to the measuring principles of the Gaia instrument it is mandatory to assign a highly stable and accurate time tag for each observational point. For this purpose Gaia has a Rb clock on board. That on-board clock is a free-running oscillator and must be regularly synchronized with TCB which is used as the underlying relativistic coordinate time scale in the whole Gaia data processing. To monitor the reading of the on-board clock with respect to TCB (or any other timescale) a one-way clock synchronization scheme is implemented. This scheme takes into account all known theoretical effects (e.g., relativity, tropospheric delay, etc.) and allows one both to monitor the health of the on-board clock and to create a clock model at the accuracy of better than 1 microsecond.

中文翻译：

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使用 Gaia 进行空间天体测量的数据定时、时间传输和机载时钟监测

本文在空间天体测量任务盖亚的框架内讨论了数据时序问题。由于与天体测量和盖亚仪器的测量原理相关的各种原因，必须为每个观测点分配一个高度稳定和准确的时间标签。为此，盖亚在船上有一个 Rb 时钟。该机载时钟是一个自由运行的振荡器，必须定期与 TCB 同步，TCB 用作整个 Gaia 数据处理中的底层相对论坐标时标。为了监控相对于 TCB（或任何其他时间刻度）的板载时钟读数，实施了一种单向时钟同步方案。该方案考虑了所有已知的理论效应（例如，相对论、对流层延迟等。