24 August 2022
UTC(OP) is the real time realization of UTC in France generated at Observatoire de Paris (OP). This timescale is at the basis of legal time disseminated in France, after adding 1 or 2 hours depending on summer or winter time. It is also the pivot for French contributions to international timescales (commercial clocks, primary frequency standards) calculated by the BIPM. UTC(OP) has been significantly improved recently. Its operation is based on the output signal of a hydrogen maser frequency daily steered thanks to the calibrations provided by the SYRTE atomic fountains, using a microphase stepper. In addition, a fine steering of the order of -15 or -16 is updated at the beginning of each month using the last publication of Circular T by the BIPM, in order to remain close to UTC. Thanks to the new method implemented, UTC(OP) is maintained to a few ns close to UTC, and corresponds to one of the best UTC(k). (more details on the web page of the Time Metrology scientific team)
TA(F) (Temps Atomique Français) is a timescale calculated at the end of each month using the data of about twenty 5071A commercial cesium clocks located in about ten different French laboratories. The data are averaged and filtered using an ARIMA algorithm. The timescale is frequency steered using the SYRTE fountain calibrations. It provides a frequency reference with an accuracy of about -15 to the contributing laboratories.
We provide daily calibrations against UTC(OP) of the local time reference generated in about 10 French laboratories, connected using GPS C/A or GPS TAIP3 common view technique ( accuracy of a few ns) : Observatoire de Besançon, Observatoire de la Côte d’Azur, located near Grasse, Observatoire de Nancay, the French spatial agency CNES, Toulouse, DGA Rennes and DGA Biscarosse, DCNS in Brest, 3 sites of Orange, located in Lannion, in St Amand, in Paris area and in Lyon Sévigné, Spectracom Orolia, Les Ulis, Keysight Technologies (previously Agilent Technilogies), Les Ulis. Most of these laboratories contribute to TA(F) with their clocks. The collected data are also transmitted to the BIPM for the French contribution to EAL.
We also operate instruments for radio navigation
Our main GPS receiver OPMT, is an IGS station
We host a station of the European navigation system EGNOS, used especially by civil aviation. The data provided by this station are used to connect ENT (EGNOS network Time) to UTC via UTC (OP).
We contribute to the development of the European navigation system GALILEO for the generation of GST (GALILEO System Time) and for time transfer systems calibration.
Finally, we disseminate continuously our time references to the public: UTC(OP) and/or French legal time are accessible
on the website heurelegalefrancaise.fr
we are also in charge of the survey of ALS162 broadcasted signal, formerly France Inter long waves signal (time code and phase of the carrier) together with Observatoire de Besançon and France horlogerie (time accuracy of the order of 1 ms, frequency accuracy of about 10-12).
via NTP servers (accuracy of a few tens of ms, )
Most of our measurement results are available daily in this web site. We also publish a monthly report, Bulletin H that summarizes the main results.