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The possibility for Lorentz/CPT-breaking, which is motivated by unification theories, can be systematically tested within the standard-model extension framework. In the pure gravity sector, the mass dimension 5 operators produce new Lorentz and CPT-breaking terms in the 2-body equations of motion that depend on the relative velocity of the bodies. In this Letter, we report new constraints on 15 independent SME coefficients for Lorentz/CPT-violations with mass dimension 5 using lunar laser ranging. We perform a global analysis of lunar ranging data within the SME framework using more than 26,000 normal points between 1969 and 2018. We also perform a jackknife analysis in order to provide realistic estimates of the systematic uncertainties. No deviation from Lorentz/CPT symmetries is reported. In addition, when fitting simultaneously for the 15 canonical SME coefficients for Lorentz/CPT-violations, we improve up to three orders of magnitude previous post-fit constraints from radio pulsars., Comment: 8 pages, 1 figure

Only a few sites on Earth are technically equipped to carry out Lunar Laser Ranging (LLR) to retroreflector arrays on the surface of the Moon. Despite the weak signal, they have successfully provided LLR range data for about 49 years, generating about 26,000 normal points. Recent system upgrades and new observatories have made millimeter-level range accuracy achievable. Based on appropriate modeling and sophisticated data analysis, LLR is able to determine many parameters associated with Earth–Moon dynamics, involving the lunar ephemeris, lunar physics, the Moon’s interior, reference frames and Earth orientation parameters. LLR has also become one of the strongest tools for testing Einstein’s theory of general relativity in the solar system. By extending the standard solution, it is possible to solve for parameters related to gravitational physics, like the temporal variation of the gravitational constant, metric parameters as well as the strong equivalence principle, preferred-frame effects and standard-model extensions. This paper provides a review about LLR measurement and analysis. After a short historical overview, we describe the key findings of LLR, the apparatus and technologies involved, the requisite modeling techniques, some recent results and future prospects on all fronts. We expect continued improvements in LLR, maintaining its lead in contributing to science.

We present an approach to testing the gravitational redshift effect using the RadioAstron satellite. The experiment is based on a modification of the Gravity Probe A scheme of nonrelativistic Doppler compensation and benefits from the highly eccentric orbit and ultra-stable atomic hydrogen maser frequency standard of the RadioAstron satellite. Using the presented techniques we expect to reach an accuracy of the gravitational redshift test of order $10^{-5}$, a magnitude better than that of Gravity Probe A. Data processing is ongoing, our preliminary results agree with the validity of the Einstein Equivalence Principle., Comment: Submitted to Physics Letters A

The Time Transfer by Laser Experiment (T2L2) on the Jason 2 satellite is a mission allowing remote clocks synchronization at the picosecond level. It is based on laser ranging technologies, with a laser station network on the ground and a dedicated instrument on board the satellite. It was launched in June 2008 and has been working continuously since then. T2L2 performances are very promising for time and frequency metrology and also for fundamental physics. The scientific objectives of the whole experiment rely on a rigorous uncertainty budget. This is governed by the characteristics of the space instrument and the laser stations network, the post treatment done on the ground, and also the process used to calibrate the laser stations. The uncertainty budget demonstrates that T2L2 is able to perform common-view time transfers between remote sites with an expanded uncertainty better than 140 ps (coverage factor = 2).

International audience; This paper presents a direct comparison between two satellite time transfer techniques: common-view (CV) of satellites from the global positioning system (GPS) constellation, and time transfer by laser link (T2L2) through the low orbiting satellite Jason-2. We describe briefly both techniques, together with two independent relative calibration campaigns of the links involving four European laboratories. Between the same remote time scale reference points, the mean values of the calibrated differences between GPS CV and T2L2 are below 240 ps, with standard deviations below 500 ps, mostly due to GPS CV. Almost all sample deviations from 0 ns are within the combined uncertainty estimates. Despite the relatively small number of common points obtained, due to the fact that T2L2 is weather dependent, these results provide an unprecedented sub-ns consistency between two independently calibrated microwave and optical satellite time transfer techniques.

This article exposes how we improved (by more than a factor of four) the green Lunar Laser Ranging instrumental sensitivity of the French telemetric station of the “Observatoire de la Côte d’Azur” in 2012. The primary reason for this success is the doubling of the pulse energy of our green Nd:YAG laser, reaching now 200 mJ at 10 Hz. This first gain is due to the replacement (inside our oscillator cavity) of the dye cell with a CR4+:YAG crystal saturable absorber. Complementary spatial beam profile improvements are also described, regarding polarisation, flashlamp geometry and specific lens arrangements (to exclude ghosts from focusing on the 8 m long amplification chain). Those combined laser enhancements pave the way to future science breakthrough linked to quasi-millimetric determination of the Earth–Moon dynamics (Murphy, 2013). Jointly, we propose an empirical thermal lensing model, varying with the cycle ratio of the flashlamps. Our model connects Koechner’s (1970) continuous pumping to our intermittent pumping case, with a “normalised heating coefficient” equalling 0.05 only if the electrical lamp input power is equal to 6 kW and scaling as this [electrical input power into the lamps] to the power of [half the pumping cycle ratio]. Keywords: Lunar Laser Ranging, Thermal lensing, Optical design

International audience; The Time Transfer by Laser Link (T2L2) experiment has been developed in close collaboration between Centre National d'Etudes Spatiales and Observatoire de la Côte d'Azur. The aim is to synchronize remote ultra-stable clocks over large-scale distances using two laser ranging stations. This ground to space time transfer has been derived from laser telemetry technology with dedicated space equipment designed to record arrival time of laser pulses on board the satellite. For 3 years, specific campaigns have been organized to prove T2L2 performance. In April 2012, we performed a 2-week campaign with our two laser ranging stations, Métrologie Optique and French Transportable Laser Ranging Station, to demonstrate the T2L2 time transfer accuracy in co-location. We have compared three independent time transfer techniques: T2L2, GPS, and direct measurement, with both an event timer and an interval counter. The most important result obtained in this campaign was a mean agreement between T2L2 and a direct comparison better than 200 ps. This is the first major step to validate the uncertainty budget of the entire T2L2 experiment. This paper focuses on this campaign setup and the obtained results.

International audience; For many years, lunar laser ranging (LLR) observations using a green wavelength have suffered an inhomogeneity problem both temporally and spatially. This paper reports on the implementation of a new infrared detection at the Grasse LLR station and describes how infrared telemetry improves this situation. Our first results show that infrared detection permits us to densify the observations and allows measurements during the new and the full Moon periods. The link budget improvement leads to homogeneous telemetric measurements on each lunar retro-reflector. Finally, a surprising result is obtained on the Lunokhod 2 array which attains the same efficiency as Lunokhod 1 with an infrared laser link, although those two targets exhibit a differential efficiency of six with a green laser link.

International audience; We present a direct comparison between two different techniques for the relative calibration of time transfer between remote time scales when using the signals transmitted by the Global Positioning System (GPS). Relative calibration estimates the delay of equipment or the delay of a time transfer link with respect to reference equipment. It is based on the circulation of some travelling GPS equipment between the stations in the network, against which the local equipment is measured. Two techniques can be considered: first a station calibration by the computation of the hardware delays of the local GPS equipment; second the computation of a global hardware delay offset for the time transfer between the reference points of two remote time scales. This last technique is called a 'link' calibration, with respect to the other one, which is a 'receiver' calibration. The two techniques require different measurements on site, which change the uncertainty budgets, and we discuss this and related issues. We report on one calibration campaign organized during Autumn 2013 between Observatoire de Paris (OP), Paris, France, Observatoire de la Côte d'Azur (OCA), Calern, France, and NERC Space Geodesy Facility (SGF), Herstmonceux, United Kingdom. The travelling equipment comprised two GPS receivers of different types, along with the required signal generator and distribution amplifier, and one time interval counter. We show the different ways to compute uncertainty budgets, leading to improvement factors of 1.2 to 1.5 on the hardware delay uncertainties when comparing the relative link calibration to the relative receiver calibration.

International audience; We present a direct comparison between two different techniques for the relative calibration of time transfer between remote time scales when using the signals transmitted by the Global Positioning System (GPS). In the remote sites, the local measurements are driving either the computation of the hardware delays of the local GPS equipment with respect to a given reference GPS receiver, a receiver calibration, or the computation of a global hardware offset between two distribution reference points of the remote time scales, a link calibration. Both techniques do not require the same measurements on site, and we discuss the uncertainty budget computation differences. We report on one calibration campaign organized during Autumn 2013 between Observatoire de Paris (OP), Paris, France, Observatoire de la Côte dAzur (OCA), Plateau de Calern, France, and NERC Space Geodesy Facility (SGF), Herstmonceux, United Kingdom. We show the different ways to compute uncertainty budgets, leading to improvement factors of 1.2 to 1.5 on the hardware delay uncertainties when comparing the relative link calibration to the relative receiver calibration.

T2L2 (Time Transfer by Laser Link) permits the synchronization of remote ultra stable clocks over intercontinental distances. The principle is based upon laser telemetry technology with a network of laser stations on ground and dedicated space equipment designed to record arrival time of laser pulses at the satellite. T2L2 allows realization of some links between distant clocks with time stability of a few picoseconds and accuracy better than 100 ps. The instrumental metrology associated with such performance needs to be designed with utmost care. This requirement concerns all the instrumentation directly linked with the specific T2L2 equipment as well as the instrumentation doing the link between the laboratory reference and the T2L2 ground segment. Several campaigns were done to demonstrate both the ultimate time accuracy and time stability capabilities of T2L2. The paper is focused on the current high accuracy equipment that has been designed for the picosecond metrology and on some recent campaigns involving global calibrations of both laser stations and GNSS equipment. Results obtained during two months of comparisons between GPS in common view and T2L2 at three European laboratories show some differences below 300 ps with a standard deviation better than 500 ps. This is the first time that two different techniques of time transfer independently calibrated are in agreement at sub-ns level over continental distances.

The International GLONASS Experiment (IGEX-98) was carried out between 19 October 1998 and 19 April 1999. Among several objectives was the precise orbit determination of GPS and GLONASS satellites and its validation by laser ranging observations. Local laser-based orbit corrections (radial, tangential and normal components in a rotating orbital local reference frame) are computed using a geometrical short-arc technique. The order of magnitude of these corrections is at the level of few decimeters, depending on the considered components. The orbit corrections are analyzed as a function of several parameters (date, orbital plane, geographical area). The mean corrections are at the level of several centimeters. However, when averaging over the entire campaign and for all the satellites, no mean radial, tangential and normal orbit corrections are found. The origin of the observed corrections is considered (errors due to the geocentric gravitational constant, the non-gravitational forces, the thermal equilibrium of on-board equipment, the reference systems, the location and the signature of the retroreflector array, and the precision of the satellite laser ranges). Some features are also due to errors in the radio-tracking GLONASS orbits. Further investigations will be needed to better understand the origin of various biases.

The Lunar Laser Ranging station at the Observatoire de la Cote d'Azur, France, permits to measure the Earth-Moon distance with millimetric precision. Applications in astronomy, lunar science, geodesy, and gravitation are summarised. Expected scientific results with millimetric Lunar Laser Ranging data are presented. A complete error budget is given, showing that the precision is mainly limited by the orientation and the size of the corner cube arrays placed on the Moon. The measurement accuracy is degraded by the bad knowledge of the air index. The time stability, computed from the lunar echoes, permits to extract the real precision of the Earth-Moon distance and to optimise the integration time of the normal points.

The Time Transfer by Laser Link (T2L2) experiment aims to synchronize remote ultra stable clocks over very long distances using the Satellite Laser Ranging (SLR) technique. T2L2 was launched in July 2008, on board the Jason2 satellite; from 5-6 stations ranging T2L2 during the first months of the mission, around 22 stations of the worldwide SLR network are now participating in the tracking. In addition to the permanent data acquisition and processing (accessible from our website https://t2l2.oca.eu/), several field experiments have been conducted to alternatively demonstrate the ultimate time transfer capability of T2L2, in terms of stability, exactness, comparison with the GPS and Two-Way microwave techniques. This paper synthetizes the best performances that T2L2 allows us to achieve, as a result of recent improvements made in the data reduction. The time stability of the T2L2 ground to space time transfer is established at 6-8 ps at 75 seconds, for SLR systems equipped with an H-maser as the reference clock. The ground to ground time transfer stability between 2 SLR stations (in Common View) is estimated at 11 ps rms (average) over one passage and better than 50 ps over several days. We present also the advantages and drawbacks of this unique time transfer technique based on an optical link.

International audience; T2L2 (Time Transfer by Laser Link), developed by both CNES and OCA permits the synchronization of remote ultra stable clocks over intercontinental distances. The principle is derived from laser telemetry technology with dedicated space equipment deigned to record arrival time of laser pulses at the satellite. Using laser pulses instead of radio frequency signals, T2L2 permits to realize some links between distant clocks with a time stability of a few picoseconds and accuracy better than 100 ps. The T2L2 space instrument is in operation onboard the satellite Jason 2 since June 2008. Several campaigns were done to demonstrate both the ultimate time accuracy and time stability capabilities. It includes some experiments implemented in co-location to directly compare T2L2 time transfer residuals with the direct link between stations, and some ground to ground time transfer between ultra stable clocks. Important works have been done, between OCA and OP, to accurately compare T2L2 with microwave time transfer GPS and TWSTFT. These comparisons are based on laser station calibrations with a dedicated T2L2 calibration station designed to accurately set the optical reference of the laser station within the PPS reference of the microwave systems. Other experiments are also planned in the future: 3D localization with the lunar space vehicle LRO, T2L2 coverage extension over the Pacific Ocean (Tahiti), DORIS comparison and a third international campaign.

The Time Transfer by Laser Link (T2L2) experiment is a joint Observatoire de la Cote d'Azur (OCA) and CNES space mission that will perform ground to ground time transfer. Using laser pulses instead of radio frequency signals, we are expecting a time stability of about 1 ps over 1,000 s and 10 ps over one day and a time accuracy in the 100 ps range. The T2L2 instrument is on board the Jason-2 space vehicle. Launched in June 2008, it has been working since this date. After a six months period devoted to the characterization and the calibration of the system, the mission has started its "operational" phase in January 2009. First ground to space time transfers have demonstrated noise levels of some tens of picoseconds and a preliminary time stability of a few picoseconds over integration times of some tens of second, clearly limited by the on-board clock. The 2009 T2L2 experimental program has contributed to the calibration / validation of T2L2 performances through two major experiments. The first one is a common clock time transfer between two co localized laser stations at the O CA : a fixed one MeO (for Optical Metrology) and the French Transportable Laser Station (FTLRS). The second experiment is the validation of remote clock comparisons using both laser and radio frequency techniques. This validation has been done using 3 regular laser stations (O CA France, Poland, Japan) and also the FTLRS station installed at Observatoire de Paris (SYRTE). The availability on those sites of GPS and TWSTFT stations allows a direct comparison with T2L2. In parallel, data processing has been improved. It now includes a compensation of the dependency of the time walk of the detector with the energy of the laser pulse and some initial filtering and interpolation process. Influence of the angle of incidence of the laser beam on the detector will also be introduced soon, together with the finalization of the filtering and interpolation strategy. The co location campaign took place from April to September 2009, with the two laser stations MeO and FTLRS connected to the same cesium clock. The FTLRS station has then been moved into Paris for 4 weeks between October and November 2009. After reminding the principle and the objectives of the mission, this paper will present first results of these experiments.

The new generation of optical time transfer (T2L2 - Time Transfer by Laser Link) under development at OCA and CNES will allow the synchronization of remote ultra stable clocks and the determination of their performances over intercontinental distances. The principle is based on the propagation of light pulses between the clocks that are to be synchronized. T2L2 is the follow-on mission to LASSO (LAser Synchronization from Stationary Orbit) with performances improved by two orders of magnitude. Expected T2L2 performances are in the 100 ps range for accuracy, with an ultimate stability better than 1ps over 1,000s and than 10ps over one day. After a short overview of the instrumental heritage and the historic course of the project up to today's acceptation on Jason 2, we will report on a ground experiment conducted by OCA permitting to envision a performance improvement of at least one order of magnitude as compared to the best time transfer techniques available. Then preliminary performance budgets for the T2L2 on Jason 2 mission will be given, based on measurements conducted by OCA and expected performances of the space instrument. We will finish with the status of the space instrument development and a summary of recently conducted measurements of the electronics breadboards performances

A series of measurements of infra-red apparent temperatures of ten selected sites in lunar maria has been undertaken in CERGA, using an infra-red receiver (11.3 μm). The experimental procedures are described. The theory of the receiver is developed and the theory of two methods of calibration of the measurements is given. This method was applied during two campaigns in 1977 and 1978, giving 142 values of temperatures.

A revision is made of the periodic publications specializing in cardiology that at present are being edited in the world. Ninety-nine titles of actual importance with a perioricity over two numbers per year formed the material of study. The oldest publication began to be printed in the year of 1908, changed name in 1937, and today is titled Archives des Maladies du Coeur et de Vaisseax. In Spanish, the first journal specializing in cardiology started in Mexico 50 years ago; in 1944 it changed name, and at present in continues to be published with the title of Archivos del Instituto de Cardiología de México. In the first decade of this century, only one publication on cardiology with the above mentioned characteristics appeared. In the first seven months of 1979, five appeared. Considerations are made concerning the alarming growth of the contemporary medical biobliography, and of cardiology in particular.