Ongoing improvements of the time and frequency references at LNE-syrte

We present the current developments performed at LNE-SYRTE, to produce a new time reference, called UTC(OP)_Maser. This time reference aims at taking benefits of our clock ensemble: the short term stability of a hydrogen maser, the mid term stability of our ensemble of industrial cesium clocks, and the accuracy of our three cold atom fountains. This paper describes an algorithm that produces a timescale optimised in terms of stability over averaging periods of 1–2 months, with a weighted average of the cesium clocks data. We also present the steering processes, involving the fountain calibrations, to drive the timescale towards UTC, and to control the hydrogen maser. The simulations, based on past data, show an improvement of a factor of 5, in terms of time accuracy, compared to the current UTC(OP). The first experimental results demonstrate a gain of more than one order of magnitude on the short term stability.