The Franco-American Swot (Surface Water and Ocean Topography) mission is launching a satellite into space to reveal the topography of surface waters with greater precision, using a wide-field interferometric radar called KaRIn.

The Gaia probe provides the most accurate three-dimensional map of our Galaxy. For this, the Gaia scientific consortium, which includes SYRTE researchers and engineers, will receive the 2023 Lancelot M. Berkeley - New York Community Trust Prize for Meritorious Work in Astronomy.

The integration of the fiber optic metrology infrastructures of the two countries, adding through interconnections the research laboratories and observatories of both countries, provides the research community with a physical layer on which new research can be developed and pursued in the long term. 


Five absolute gravimeters are currently compared at the LNE gravimetry reference site in Trappes. Four of these five absolute gravimeters are part of the National Instrumental Park (NIP) PGrav managed by the ’Action Spécifique’ Gravimetry Resif. These measurement campaigns are essential to test the accuracy of the instruments.

Will the LISA mission be able to measure magnetism of neutron stars and white dwarfs in binary systems?

The Sagnac effect played an important role in the foundations of the theory of relativity, that led to the development of precision optical interferometers to check the agreement with theory. The Atomic Interferometry and Inertial Sensors team of SYRTE has recently published a precise test of the Sagnac effect using matter waves. The team was able to measure the phase shift induced by the Earth’s rotation and find an agreement with the theoretical prediction at a precision level of 25 parts per million.

Soon the last stroke of the speaking clock will happen.
A look back at almost 90 years of history, and how to get the correct time after July the 1st at midnight and one second.

Sébastien Bize, CNRS research director at the Systèmes de Référence Temps-Espace (SYRTE) laboratory, is the 2022 winner of the European Frequency and Time Award from the European Frequency and Time Forum (EFTF). The award recognises his outstanding contribution to the development of microwave and optical frequency standards for fundamental physics tests and for the realisation of the time unit of the International System of Units.

The Ministry of Higher Education, Research and Innovation has just unveiled the new national roadmap for Research Infrastructures. REFIMEVE is one of the new infrastructures listed in the roadmap.

In an highly collaborative experiment led by NPL (UK), involving 32 authors from three countries and five institutions: NPL(UK), RENATER, LPL and LNE-SYRTE (France) and PTB (Germany), the international consortium has set a new record for comparing distant ultra-stable lasers 750 kilometres apart. The optical comparison is made through a world-record long optical fiber links of 2,220 kilometres and 2 interconnections within the French optical fiber network REFIMEVE, a new National Research Infrastructure in France. Even using cutting-edge optical frequency standards, the team has been able to demonstrate that their measurement precision is preserved when transmitted across stabilized optical fibre.

The International Astronomy Union (IAU) has just awarded the 2021 nominees that recognises the outstanding scientific achievements of 9 astronomy PhD students around the world. Etienne Savalle, who prepared his thesis under the supervision of Peter Wolf, was rewarded in the category Fundamental astronomy.

Astrometry of very high precision on the ground or in space, in radio or optics, reveals a little more the machinery of the AGN.

Rising sea levels reflect far-reaching environmental and climatic effects. The new Sentinel-6 (Michael Freilich) satellite will improve and continue our monitoring of rising seas with even greater accuracy.

The orientation of the SEIS seismometer, dropped on Mars in December 2018 by the InSight probe, must be known precisely to be really useful. But Mars, like the Moon, does not have a sufficiently strong magnetic field. A compass will not be able to indicate the direction of North. A solution for orientation, proposed by a research team from SYRTE (Obs Paris/PSL-CNRS-SU-LNE), consisted of using the shadow of a gnomon illuminated by the Sun to determine the meridian of the location: this is how, on 1 January 2019, it was possible to find the Martian geographic North using an instrument that dates back to ancient times.

A new method of nondestructive detection of the quantum state of laser-cooled atoms has been demonstrated by a SYRTE team. Non-destructive methods, which preserve the state of the cold atom gas almost intact after its measurement, is one of the important objectives set by the ten-year program for the development of quantum technologies as defined by the European Union. It is also an important technological milestone that has just been passed for the industrial manufacture of compact cold atom quantum sensors.

A Franco-Australian team has set a new world record for frequency-stabilized laser transmission by combining phase stabilization technology with advanced self-guided optical terminals. Together, these technologies made it possible to send laser signals from one point to another by correcting fluctuations introduced by atmospheric turbulence. This is the world’s most accurate method for comparing clocks between two distinct locations.

A direct comparison of five optical clocks and six atomic fountains, located at INRIM, LNE-SYRTE, NPL and PTB, was performed using two high-performance satellite techniques: broadband TWSTFT and GPS PPP. This was the first time that very wide band (20 Mchip/s) pseudo-random noise codes available on commercial TWSTFT modems were used for optical clock comparisons. This campaign represented the most comprehensive coordinated simultaneous operation of optical clocks to date.

T-REFIMEVE, coordinated by Laboratoire de Physique des Lasers, and co-coordinated by SYRTE, winners of the call for Equipements structurants pour la recherche

Pacôme Delva is awarded the 2020 Medal of the Academia of Air and Space

Denis Savoie, an associate member of SYRTE, a recognized expert in sundials, is the winner of the Gaïa 2020 Prize!

Christian Bizouard, Geophysical Modeling of the Polar Motion, De Gruyter Studies in Mathematical Physics, 31, 372 p.

Rémi Geiger is nominated as junior member of IUF as of 1st october, 2020

Four different French institutions (EOST in Strasbourg, OBSPM in Paris, OREME in Montpellier and LSSB in Rustrel) operate four different sites in France that contribute to the International Geodynamic and Tidal Service IGETS.

An all-fibered frequency-stabilized laser source device whose volume does not exceed 30 liters is being developed at SYRTE by the optical frequency metrology team. This device consists of a telecom C-band laser source at 1.5 µm (near IR) supplemented by an original frequency tripling device developed and patented by SYRTE. The device is then associated with a molecular transition of iodine to 515 nm (green) which serves as a frequency reference.

L’application web DISHAS (Digital Information System for the History of Astral Sciences) est opérationnelle depuis fin mai 2020.
Après quatre ans de modélisation et développement au sein d’une équipe internationale pilotée au SYRTE elle commence à recevoir ses premières données historiques.

The web application DISHAS (Digital Information System for the History of Astral Sciences) is operational since the end of May 2020.

After four years of modeling and development work within an international team led by SYRTE, it starts to receive its first historical data.

C. Schmit, La philosophie naturelle de Malebranche au XVIIIe siècle - Inertie, causalité, petits tourbillons
Classiques Garnier, Collection Histoire et philosophie des sciences, 21, 2020, 809 p.

The prize rewards Arnaud Landragin’s research works in the field of atomic gravimetry and their successful transfer to industry.

Le prix récompense les travaux de recherche d’Arnaud Landragin dans le domaine de la gravimétrie atomique et leur transfert réussi dans l’industrie.

For the first time, Two-Way Satellite Time and Frequency Transfer between LNE-SYRTE and PTB, improved by Software-Defined Radio solution, is used for International Atomic Time (TAI) and Coordinated Universal Time (UTC) computations.

For the first time, spectral measurements of five stars orbiting the supermassive black hole in our Galactic Center leads to a direct constraint on a possible variation of the fine structure constant.

Pour la première fois, des mesures spectrales de cinq étoiles atour du trou noir supermassif au centre de notre galaxie permettent de contraindre des variations de la constante de structure fine.

856-km coherent optical link is estabished between Paris and Grenoble. This is a worl record on such a distance and an important step for REFIMEVE.

Mise en service d’un lien optique de 856 km entre Paris et Grenoble. C’est un record mondial sur une telle distance et une étape importante de la construction de l’instrument REFIMEVE+,

The sismicity and eruptivity of the Giant of Siciliy could be activated, at interannual time scales, by the pole tide, directly related to the motion of the Earth’s rotation pole about the mean pole. Study published by Sébastien Lambert and Gianluca Sottili (Is there an influence of the pole tide on volcanism? Insights from Mount Etna recent activity, Geophysical Research Letters, DOI:10.1029/2019GL085525, 2019).

La sismicité et le volcanisme du géant de Sicile activés en partie par les écarts de l’axe de rotation de la Terre ? Etude publiée par Sébastien Lambert (Observatoire de Paris) et Gianluca Sottili (Université de Rome).

Le Prix, décerné par l’Académie des Sciences, récompense les travaux de Suzanne Débarbat pour son œuvre en histoire des sciences.

The Prize, awarded by the Academy of Sciences, recognizes Suzanne Débarbat’s work in the history of science.

The second of the International System of Units (SI) is defined from the hyperfine transition of the 133Cs atom. In the current context where many new generation optical clocks surpass 133Cs based clocks, could the second one be redefined, not from a single transition but from several? An article published in Metrologia proposes such a definition, and shows that it is free of contradiction and feasible according to all the criteria in effect at the Comité International des Poids et Mesures (CIPM).

G7-research delegates (from Germany, Canada, USA, France, Italy, Japan, UK) and EU-delegates had a visit at SYRTE on Thursday 20 june, 2019.

Le premier numéro des "Archives Internationales d’Histoire des Sciences" vient de paraître

The SYRTE gyroscope beats new performance records !

The first quantum commercial gravimeter, derived from SYRTE research and marketed by the start-up Muquans, was delivered. In-field measurement campaigns, lasting about one month, were carried out sucessfully.

Des physiciens du LP2N, du SYRTE et du CNES viennent de tester le principe d’équivalence d’Einstein à bord de l’airbus A310 zero-G

Remi Geiger (Paris Observatory) and Michael Trupke (Vienna University) have proposed a conceptually new way of testing the foundational principle of General Relativity with a system of two entangled atoms

The prize recognizes the work of Michel Abgrall, Jocelyne Guéna et Daniele Rovera related to the realization, the use and the provision of primary frequency and time references.
A list of publications linked to the work can be found here.
Find more on the website of LNE or of Observatoire de Paris.

L’évènement El Niño de 2015-16 a été l’un des plus puissants des quarante dernières années. Comme ses monstrueux prédécesseurs de 1982-83 et 1997-98, il a ralentit la rotation de la Terre de presque 1 ms pendant quelques semaines. Mais les mécanismes atmosphériques entrant en jeu cette fois-ci sont fondamentalement différents des fois précédentes, dû à la nature "hybride" du phénomène. Explications.

La base de données La mesure du temps dans l’Antiquité. Témoignages archéologiques est en ligne et nous invite à un voyage dans le temps !

A positive leap second was inserted in the national reference time UTC(OP) on 31 December 2016:
2016-12-31 T 23h 59min 59s 23h 59min 60s 00h 00min 00s (UTC)
2017-01-01 T 00h 59min 59s 00h 59min 60s 01h 00min 00s (Local time)

Nicole Capitaine, astronome au SYRTE, a été nommée Correspondante de l’Observatoire Royal de Belgique au cours d’un atelier consacré à la nutation rassemblant géophysiciens et astronomes dont plusieurs membres du SYRTE.

ESA and DPAC release the first results of the space mission GAIA, launched about 1000 days before. The results show the unique measure of the distance to many stars and improve the precision of the one already known from the Hipparcos catalogue by a factor of 3.

Atomic clocks at SYRTE provide new limits on scalar dark matter!

1400-km of optical fiber link connects the quantum clocks at SYRTE and PTB, and is used to compare them with record uncertainty !

The SYRTE’s gyrometer breaks sensitivity record using a joint interrogation scheme.

During the winter 2015-2016 El-Nino has a visible influence on the length of day, causing an anamoly of 0.5 ms. Such strong El-Nino go back to 1983-1983 or 1997-1998.

Une campagne de mesure du seeing menée par François Taris depuis l’observatoire du Pic de Châteaurenard (3000m) a débuté en octobre 2014. Ces mesures visent à (re-)qualifier le site en vue de l’implantation d’un télescope robotique. Cet instrument sera dédié au monitoring optique des quasars et au suivi d’astéroïdes dans le cadre du raccordement des systèmes de référence.

A seeing measurement campaign is being operated by François Taris at Pic de Châteaurenard (3000 m), close to Saint-Véran. It started october 2014. These measurements aims at characterizing the site. In case of positive results, a robotic telescope will be set up there. The telescope will be dedicated to monitoring of quasars in the optical and follow-up of asteroids in the framework of celestial reference frame tie.

First comparison between two absolute atom gravimeters at LNE Trappes from the 28^th of september to the the 2^nd of octobre 2015.

The MIGA project aims at realizing of a novel infrastructure to study applied and fundamental aspects of gravity using matter wave and optical interferometry techniques in a single instrument. This infrastructure will allow for a deeper understanding of the Earth’s gravity field and serve as a test bench for future low frequency (0.1-10 Hz) terrestrial gravitational wave detectors based on atom interferometry. A milestone of the project was achieved in June 2015 by the successful delivery to (...)

Making use of data that are generated primary for the tracking of Gaia, the Gaia’s GBOT campaign has now found an additional science application: the detection of asteroids.

July 2014 : the CNES has delivered Pharao, an ultra-accurate atom clock, to the european space agency.

The Rubiclock experiment has flown during march 2014, on board the A-300 Zero-G.