http://sedici.unlp.edu.ar:80/handle/10915/191954 Sun, 15 Nov 2026 21:59:05 GMT 2026-11-15T21:59:05Z http://sedici.unlp.edu.ar:80/handle/10915/192193 Objeto de conferencia IAU Symposium 401 (La Plata, 4 al 9 de agosto de 2025); https://sedici.unlp.edu.ar/handle/10915/190232; IAU Symposium 401: Advancing Reference Systems, Ephemeris, and Standards: from the Earth and the Moon to Solar System Bodies. Book of Abstracts We present figures and tables of our results for DT=TT-UT in the period -720 to +1950 obtained principally from analyses of historical records of solar eclipses (-720 to +1600) and timings of lunar occultations ( + 1600 to + 1950) [1], These show changes in the Earth’s rate of rotation as measured in changes of the length of the day (lod). There is a long-term deceleration producing an increase in the lod of +1.72 ms cy-1. There are also centennial fluctuations in the lod of amplitude 3 ms. After +1600 the data are precise enough to reveal decade fluctuations of up to an amplitude of 4 ms. Wed, 01 Jan 2025 00:00:00 GMT http://sedici.unlp.edu.ar:80/handle/10915/192193 2025-01-01T00:00:00Z We present figures and tables of our results for DT=TT-UT in the period -720 to +1950 obtained principally from analyses of historical records of solar eclipses (-720 to +1600) and timings of lunar occultations ( + 1600 to + 1950) [1], These show changes in the Earth’s rate of rotation as measured in changes of the length of the day (lod). There is a long-term deceleration producing an increase in the lod of +1.72 ms cy-1. There are also centennial fluctuations in the lod of amplitude 3 ms. After +1600 the data are precise enough to reveal decade fluctuations of up to an amplitude of 4 ms. http://sedici.unlp.edu.ar:80/handle/10915/192191 Objeto de conferencia IAU Symposium 401 (La Plata, 4 al 9 de agosto de 2025); https://sedici.unlp.edu.ar/handle/10915/190232; IAU Symposium 401: Advancing Reference Systems, Ephemeris, and Standards: from the Earth and the Moon to Solar System Bodies. Book of Abstracts The Queqiao-2 relay satellite of the Chang’e-7 mission is equipped with a 4.2-meter radio telescope, which has successfully carried out a number of joint lunar-Earth ultra-long baseline VLBI observations with ground-based VLBI stations. For these observations, we computed both the ground-space VLBI-defined and DOR-defined geometric delay model. These models were used to obtain VLBI fringes, perform Delta-DOR. local correlation processing and extract Doppler frequency measurements. Wed, 01 Jan 2025 00:00:00 GMT http://sedici.unlp.edu.ar:80/handle/10915/192191 2025-01-01T00:00:00Z The Queqiao-2 relay satellite of the Chang’e-7 mission is equipped with a 4.2-meter radio telescope, which has successfully carried out a number of joint lunar-Earth ultra-long baseline VLBI observations with ground-based VLBI stations. For these observations, we computed both the ground-space VLBI-defined and DOR-defined geometric delay model. These models were used to obtain VLBI fringes, perform Delta-DOR. local correlation processing and extract Doppler frequency measurements. http://sedici.unlp.edu.ar:80/handle/10915/192190 Objeto de conferencia IAU Symposium 401 (La Plata, 4 al 9 de agosto de 2025); https://sedici.unlp.edu.ar/handle/10915/190232; IAU Symposium 401: Advancing Reference Systems, Ephemeris, and Standards: from the Earth and the Moon to Solar System Bodies. Book of Abstracts Precision interplanetary ranges (range points) are essential for building modern planetary ephemerides. In particular, Earth-Mercury range points allow not only to determine the orbit of Mercury but also to study physical properties of the Sun and test general relativity [1]. While there exist publicly available range points derived in JPL [2, 3] from raw MESSENGER radio science data, we aim to provide an independent analysis. Wed, 01 Jan 2025 00:00:00 GMT http://sedici.unlp.edu.ar:80/handle/10915/192190 2025-01-01T00:00:00Z Precision interplanetary ranges (range points) are essential for building modern planetary ephemerides. In particular, Earth-Mercury range points allow not only to determine the orbit of Mercury but also to study physical properties of the Sun and test general relativity [1]. While there exist publicly available range points derived in JPL [2, 3] from raw MESSENGER radio science data, we aim to provide an independent analysis. http://sedici.unlp.edu.ar:80/handle/10915/192189 Objeto de conferencia IAU Symposium 401 (La Plata, 4 al 9 de agosto de 2025); https://sedici.unlp.edu.ar/handle/10915/190232; IAU Symposium 401: Advancing Reference Systems, Ephemeris, and Standards: from the Earth and the Moon to Solar System Bodies. Book of Abstracts Fitting asteroid masses using planetary ephemerides is a well-studied technique, but traditional implementations face challenges such as correlations between asteroid masses, poorly characterized systematic errors, and overtting. We present a method that applies linearization and principal component analysis (PCA) to the accelerations induced by unmodeled asteroids on solar system bodies. Wed, 01 Jan 2025 00:00:00 GMT http://sedici.unlp.edu.ar:80/handle/10915/192189 2025-01-01T00:00:00Z Fitting asteroid masses using planetary ephemerides is a well-studied technique, but traditional implementations face challenges such as correlations between asteroid masses, poorly characterized systematic errors, and overtting. We present a method that applies linearization and principal component analysis (PCA) to the accelerations induced by unmodeled asteroids on solar system bodies. http://sedici.unlp.edu.ar:80/handle/10915/192185 Objeto de conferencia IAU Symposium 401 (La Plata, 4 al 9 de agosto de 2025); https://sedici.unlp.edu.ar/handle/10915/190232; IAU Symposium 401: Advancing Reference Systems, Ephemeris, and Standards: from the Earth and the Moon to Solar System Bodies. Book of Abstracts The International Earth Rotation and Reference Systems Service (IERS) Conventions describes the reference systems realized by the IERS, in addition to developing and maintaining the models and procedures used to support this endeavor. The IERS Conventions Centre has been preparing to release an updated conventions from the current Conventions (2010). This presentation will give an overview of the IERS Conventions as well as discuss the proposed changes to the chapters and their technical content including the changes in the associated experts and editors. Wed, 01 Jan 2025 00:00:00 GMT http://sedici.unlp.edu.ar:80/handle/10915/192185 2025-01-01T00:00:00Z The International Earth Rotation and Reference Systems Service (IERS) Conventions describes the reference systems realized by the IERS, in addition to developing and maintaining the models and procedures used to support this endeavor. The IERS Conventions Centre has been preparing to release an updated conventions from the current Conventions (2010). This presentation will give an overview of the IERS Conventions as well as discuss the proposed changes to the chapters and their technical content including the changes in the associated experts and editors. http://sedici.unlp.edu.ar:80/handle/10915/192184 Objeto de conferencia IAU Symposium 401 (La Plata, 4 al 9 de agosto de 2025); https://sedici.unlp.edu.ar/handle/10915/190232; IAU Symposium 401: Advancing Reference Systems, Ephemeris, and Standards: from the Earth and the Moon to Solar System Bodies. Book of Abstracts The Galilean satellites are locked in a 1:1 spin-orbit resonance. Their rotation axis is assumed to be in a Cassini state and to follow the long-term precession of the orbit normal. The obliquity, which is the angular separation between the rotation axis and the orbit normal, is expected to be small. Wed, 01 Jan 2025 00:00:00 GMT http://sedici.unlp.edu.ar:80/handle/10915/192184 2025-01-01T00:00:00Z The Galilean satellites are locked in a 1:1 spin-orbit resonance. Their rotation axis is assumed to be in a Cassini state and to follow the long-term precession of the orbit normal. The obliquity, which is the angular separation between the rotation axis and the orbit normal, is expected to be small. http://sedici.unlp.edu.ar:80/handle/10915/192183 Objeto de conferencia IAU Symposium 401 (La Plata, 4 al 9 de agosto de 2025); https://sedici.unlp.edu.ar/handle/10915/190232; IAU Symposium 401: Advancing Reference Systems, Ephemeris, and Standards: from the Earth and the Moon to Solar System Bodies. Book of Abstracts Despite the growing enthusiasm for AI in space applications, AI-based orbit determination is still a relatively new field with limited practical implementations [1-3]. A promising new development is Physics-Informed Extreme Learning Machine (PIELM) [4], It combines the rapid training capabilities of Extreme Learning Machines (ELM) with the physics-informed strengths of Physics-Informed Neural Networks (FINN), which ensures solutions consistent with physical laws and actual measurements. This synergy makes PIELM well-suited for solving the complex orbit determination problem. Wed, 01 Jan 2025 00:00:00 GMT http://sedici.unlp.edu.ar:80/handle/10915/192183 2025-01-01T00:00:00Z Despite the growing enthusiasm for AI in space applications, AI-based orbit determination is still a relatively new field with limited practical implementations [1-3]. A promising new development is Physics-Informed Extreme Learning Machine (PIELM) [4], It combines the rapid training capabilities of Extreme Learning Machines (ELM) with the physics-informed strengths of Physics-Informed Neural Networks (FINN), which ensures solutions consistent with physical laws and actual measurements. This synergy makes PIELM well-suited for solving the complex orbit determination problem. http://sedici.unlp.edu.ar:80/handle/10915/192182 Objeto de conferencia IAU Symposium 401 (La Plata, 4 al 9 de agosto de 2025); https://sedici.unlp.edu.ar/handle/10915/190232; IAU Symposium 401: Advancing Reference Systems, Ephemeris, and Standards: from the Earth and the Moon to Solar System Bodies. Book of Abstracts The contribution to UTC by time and frequency laboratories is commonly achieved through RINEX and CGGTTS files derived from GNSS measurement data [1]. These text-based files are typically generated from continuous binary streams, from which partial extracts can be obtained. CGGTTS files conforming to the BIPM standard are produced by dedicated software using two preceding days of RINEX streams, where the navigation RINEX file provides critical ephemeris corrections, including precise orbital position coordinates for GNSS constellation satellites. Wed, 01 Jan 2025 00:00:00 GMT http://sedici.unlp.edu.ar:80/handle/10915/192182 2025-01-01T00:00:00Z The contribution to UTC by time and frequency laboratories is commonly achieved through RINEX and CGGTTS files derived from GNSS measurement data [1]. These text-based files are typically generated from continuous binary streams, from which partial extracts can be obtained. CGGTTS files conforming to the BIPM standard are produced by dedicated software using two preceding days of RINEX streams, where the navigation RINEX file provides critical ephemeris corrections, including precise orbital position coordinates for GNSS constellation satellites. http://sedici.unlp.edu.ar:80/handle/10915/192180 Objeto de conferencia IAU Symposium 401 (La Plata, 4 al 9 de agosto de 2025); https://sedici.unlp.edu.ar/handle/10915/190232; IAU Symposium 401: Advancing Reference Systems, Ephemeris, and Standards: from the Earth and the Moon to Solar System Bodies. Book of Abstracts Since the discovery of (15760) 1992 QB1 [6], the number of trans-Neptunian objects (TNOs) identi ed has grown signi cantly. By February 2024, more than 4800 TNOs were known, with only about 210 of them with measured diameters. With the new data from the Legacy Survey of Space and Time (LSST), this number will grow signi cantly, deepening our understanding of the origin and evolution of the Solar System [1]. However, due to their distance, knowledge about their sizes, shapes, albedos, densities, and atmospheres remains sparse [2]. Stellar occultations allow for precise determinations of these parameters. A stellar occultation occurs when a Solar System object passes in front of a star, casting a shadow on Earth. This shadow re ects the object's projection at the moment of occultation [5]. Quaoar, a TNO with a semi-major axis of 43 au and an inclination of 8 degrees is classi ed as a hot classical TNO [4]. It has a satellite, Weywot, and two rings beyond the Roche limit [8]. These rings suggest alternative mechanisms for their formation and stability [7]. Wed, 01 Jan 2025 00:00:00 GMT http://sedici.unlp.edu.ar:80/handle/10915/192180 2025-01-01T00:00:00Z Since the discovery of (15760) 1992 QB1 [6], the number of trans-Neptunian objects (TNOs) identi ed has grown signi cantly. By February 2024, more than 4800 TNOs were known, with only about 210 of them with measured diameters. With the new data from the Legacy Survey of Space and Time (LSST), this number will grow signi cantly, deepening our understanding of the origin and evolution of the Solar System [1]. However, due to their distance, knowledge about their sizes, shapes, albedos, densities, and atmospheres remains sparse [2]. Stellar occultations allow for precise determinations of these parameters. A stellar occultation occurs when a Solar System object passes in front of a star, casting a shadow on Earth. This shadow re ects the object's projection at the moment of occultation [5]. Quaoar, a TNO with a semi-major axis of 43 au and an inclination of 8 degrees is classi ed as a hot classical TNO [4]. It has a satellite, Weywot, and two rings beyond the Roche limit [8]. These rings suggest alternative mechanisms for their formation and stability [7]. http://sedici.unlp.edu.ar:80/handle/10915/192176 Objeto de conferencia IAU Symposium 401 (La Plata, 4 al 9 de agosto de 2025); https://sedici.unlp.edu.ar/handle/10915/190232; IAU Symposium 401: Advancing Reference Systems, Ephemeris, and Standards: from the Earth and the Moon to Solar System Bodies. Book of Abstracts The Bureau of Products and Standards (BPS) is a key component of the Global Geodetic Observing System (GGOS) of the International Association of Geodesy (IAG). It supports GGOS in its goal to provide consistent geodetic products needed to monitor, map, and understand changes in the Earth’s shape, rotation, and gravity field. A major objective of the BPS is to keep track and foster homogenization of adopted geodetic standards and conventions as a fundamental basis for the generation of consistent geodetic products, such as the celestial reference frame, the terrestrial reference frame, Earth Orientation Parameters, satellite orbits, gravity field models and heights. This requires a close collaboration across all IAG components, as well as with other bodies dealing with standards and conventions, such as the IAU Commission A3 ’’Fundamental Standards”, the International Organization for Standardization (ISO) and the Committee on Data for Science and Technology (CODATA). This contribution presents the role of the BPS and it highlights some of the recent activities. A key issue is the regular update of the BPS inventory of standards and conventions used for the generation of geodetic products to incorporate the latest developments in the field. Further activities focus on the description and promotion of geodetic products to make other disciplines and society aware of geodesy and its beneficial products, and on the definition of Essential Geodetic Variables (EGVs). Wed, 01 Jan 2025 00:00:00 GMT http://sedici.unlp.edu.ar:80/handle/10915/192176 2025-01-01T00:00:00Z The Bureau of Products and Standards (BPS) is a key component of the Global Geodetic Observing System (GGOS) of the International Association of Geodesy (IAG). It supports GGOS in its goal to provide consistent geodetic products needed to monitor, map, and understand changes in the Earth’s shape, rotation, and gravity field. A major objective of the BPS is to keep track and foster homogenization of adopted geodetic standards and conventions as a fundamental basis for the generation of consistent geodetic products, such as the celestial reference frame, the terrestrial reference frame, Earth Orientation Parameters, satellite orbits, gravity field models and heights. This requires a close collaboration across all IAG components, as well as with other bodies dealing with standards and conventions, such as the IAU Commission A3 ’’Fundamental Standards”, the International Organization for Standardization (ISO) and the Committee on Data for Science and Technology (CODATA). This contribution presents the role of the BPS and it highlights some of the recent activities. A key issue is the regular update of the BPS inventory of standards and conventions used for the generation of geodetic products to incorporate the latest developments in the field. Further activities focus on the description and promotion of geodetic products to make other disciplines and society aware of geodesy and its beneficial products, and on the definition of Essential Geodetic Variables (EGVs). http://sedici.unlp.edu.ar:80/handle/10915/192174 Objeto de conferencia IAU Symposium 401 (La Plata, 4 al 9 de agosto de 2025); https://sedici.unlp.edu.ar/handle/10915/190232; IAU Symposium 401: Advancing Reference Systems, Ephemeris, and Standards: from the Earth and the Moon to Solar System Bodies. Book of Abstracts For millennia, humans used asterisms to track seasons, tell cultural stories, and measure time, as seen in artifacts like the Dendera Zodiac (circa 50 BCE) and the Babylonian MUL.APIN. John Flamsteed’s Atlas Coclcstis (1729) reflects this, mapping stars within traditional asterisms while including some telescopic stars. Flamsteed preserved overlaps, such as Capricornus’ stars in Aquarius’ arm, However, Eugène Delporte’s 1930 IAU standardization introduced 88 constellation boundaries using straight lines of right ascension and declination, aligned to the B 1875.0 and B 1900.0 epochs, fundamentally changing this system. Using Carte du Ciel software to observe existing constellation boundaries and Flamsteed’s charts, we identified discrepancies in the Pisces-Aquarius-Capricornus-Cetus region. Stars like 11 Peg, HD 209522, HD 210848, and Eta Psa were reassigned by Delporte’s lines disrupting cultural coherence Today, celestial maps’ original roles—seasonal prediction, storytelling, and timekeeping—are obsolete, replaced by digital age technologies like meteorology and atomic clocks. Delporte’s earth-centric boundaries also face obsolescence due to precession and stellar motion, We advocate for a dual framework to preserve cultural heritage while advancing astronomical precision, archiving cultural asterisms as borderless to preserve their historical significance, while adopting a universe-centric system using the International Celestial Reference System (ICRS) and Gaia’s 3D stellar data, balancing heritage with future astronomical precision. This approach not only honors our astronomical heritage but also embraces the precision required for future celestial exploration. Wed, 01 Jan 2025 00:00:00 GMT http://sedici.unlp.edu.ar:80/handle/10915/192174 2025-01-01T00:00:00Z For millennia, humans used asterisms to track seasons, tell cultural stories, and measure time, as seen in artifacts like the Dendera Zodiac (circa 50 BCE) and the Babylonian MUL.APIN. John Flamsteed’s Atlas Coclcstis (1729) reflects this, mapping stars within traditional asterisms while including some telescopic stars. Flamsteed preserved overlaps, such as Capricornus’ stars in Aquarius’ arm, However, Eugène Delporte’s 1930 IAU standardization introduced 88 constellation boundaries using straight lines of right ascension and declination, aligned to the B 1875.0 and B 1900.0 epochs, fundamentally changing this system. Using Carte du Ciel software to observe existing constellation boundaries and Flamsteed’s charts, we identified discrepancies in the Pisces-Aquarius-Capricornus-Cetus region. Stars like 11 Peg, HD 209522, HD 210848, and Eta Psa were reassigned by Delporte’s lines disrupting cultural coherence Today, celestial maps’ original roles—seasonal prediction, storytelling, and timekeeping—are obsolete, replaced by digital age technologies like meteorology and atomic clocks. Delporte’s earth-centric boundaries also face obsolescence due to precession and stellar motion, We advocate for a dual framework to preserve cultural heritage while advancing astronomical precision, archiving cultural asterisms as borderless to preserve their historical significance, while adopting a universe-centric system using the International Celestial Reference System (ICRS) and Gaia’s 3D stellar data, balancing heritage with future astronomical precision. This approach not only honors our astronomical heritage but also embraces the precision required for future celestial exploration. http://sedici.unlp.edu.ar:80/handle/10915/192173 Objeto de conferencia IAU Symposium 401 (La Plata, 4 al 9 de agosto de 2025); https://sedici.unlp.edu.ar/handle/10915/190232; IAU Symposium 401: Advancing Reference Systems, Ephemeris, and Standards: from the Earth and the Moon to Solar System Bodies. Book of Abstracts The Arecibo Observatory had the world’s most powerful planetary radar system until December 2020, which provided ground-based observations whose quality could only be exceeded with a spacecraft flyby. Radar allows one to characterize near-Earth asteroids (NBAs) in terms of size, shape, spin, and surface properties, and to discover natural satellites that form binary and triple asteroid systems. In addition, radar astrometry is a valuable tool for orbit refinement, providing precise measurements that can significantly improve the accuracy of orbit determination, Every year about 40-60 recently discovered NBAs were observed at Arecibo. Radar offers the great advantage of controlling the properties of the transmitted signal. The changes in the received echo compared to the transmitted signal provides clues about the characteristics of the object. The time de­ lay gives information about the distance to a target with precision as fine as meters, and the Doppler-shifted frequency of the echo provides the radial velocity with precision as fine as mm/s, making it possible to detect even small changes in the orbit due to perturbations, such as the nongravitational acceleration generated by the Yarkovsky effect. Radar astrometry can also quickly eliminate impact false alarms with the improvement of estimates of an asteroid’s orbital elements. Therefore, radar astrometry is crucial for planetary defense. We will present an overview of radar astrometric observations of NBAs obtained using the Arecibo planetary radar system during nearly 60 years of operations and how their orbits were secured after radar observations. Especially for newly discovered objects, that usually have large orbit uncertainties, Doppler and/or range measurements can prevent the object from being lost and requiring re-discovery in the future. Wed, 01 Jan 2025 00:00:00 GMT http://sedici.unlp.edu.ar:80/handle/10915/192173 2025-01-01T00:00:00Z The Arecibo Observatory had the world’s most powerful planetary radar system until December 2020, which provided ground-based observations whose quality could only be exceeded with a spacecraft flyby. Radar allows one to characterize near-Earth asteroids (NBAs) in terms of size, shape, spin, and surface properties, and to discover natural satellites that form binary and triple asteroid systems. In addition, radar astrometry is a valuable tool for orbit refinement, providing precise measurements that can significantly improve the accuracy of orbit determination, Every year about 40-60 recently discovered NBAs were observed at Arecibo. Radar offers the great advantage of controlling the properties of the transmitted signal. The changes in the received echo compared to the transmitted signal provides clues about the characteristics of the object. The time de­ lay gives information about the distance to a target with precision as fine as meters, and the Doppler-shifted frequency of the echo provides the radial velocity with precision as fine as mm/s, making it possible to detect even small changes in the orbit due to perturbations, such as the nongravitational acceleration generated by the Yarkovsky effect. Radar astrometry can also quickly eliminate impact false alarms with the improvement of estimates of an asteroid’s orbital elements. Therefore, radar astrometry is crucial for planetary defense. We will present an overview of radar astrometric observations of NBAs obtained using the Arecibo planetary radar system during nearly 60 years of operations and how their orbits were secured after radar observations. Especially for newly discovered objects, that usually have large orbit uncertainties, Doppler and/or range measurements can prevent the object from being lost and requiring re-discovery in the future. http://sedici.unlp.edu.ar:80/handle/10915/192171 Objeto de conferencia IAU Symposium 401 (La Plata, 4 al 9 de agosto de 2025); https://sedici.unlp.edu.ar/handle/10915/190232; IAU Symposium 401: Advancing Reference Systems, Ephemeris, and Standards: from the Earth and the Moon to Solar System Bodies. Book of Abstracts Numerical integration ephemerides are highly valued in both research and engineering due to their exceptional precision. However, their application in theoretical studies, particularly in the investigation of rotation and evolution, is constrained by their finite available time spans. In our previous work, we effectively explored an analytical representation of the mean longitude of Titan from the Jet Propulsion Laboratory (JPL) ephemerides. We established this representation as a function of combinations of proper frequencies and compared the results with those obtained from the synthetic ephemerides of the Théorie Analytique des Satellites de Saturne (TASS), Building upon this, we have extended our analytical representations beyond the mean longitude to the other osculating elements of the Titan ephemeris. This enables us to develop new synthetic representations that combine the strengths of both approaches: the long-term stability and system complexity inherent in TASS. In our current work, we have shifted our focus to the NOE ephemerides from the Paris Observatory. Unlike the JPL ephemerides and the synthetic TASS ephemerides, the NOE ephemerides account for Saturn’s tidal effects and long-period solar terms within their perturbation calculations. This results in a more complex analytical representation of the NOE ephemeris compared to the JPL ephemeris. Notably, these representations encapsulate crucial dynamical information, including proper frequencies, which are invaluable for theoretical research. Wed, 01 Jan 2025 00:00:00 GMT http://sedici.unlp.edu.ar:80/handle/10915/192171 2025-01-01T00:00:00Z Numerical integration ephemerides are highly valued in both research and engineering due to their exceptional precision. However, their application in theoretical studies, particularly in the investigation of rotation and evolution, is constrained by their finite available time spans. In our previous work, we effectively explored an analytical representation of the mean longitude of Titan from the Jet Propulsion Laboratory (JPL) ephemerides. We established this representation as a function of combinations of proper frequencies and compared the results with those obtained from the synthetic ephemerides of the Théorie Analytique des Satellites de Saturne (TASS), Building upon this, we have extended our analytical representations beyond the mean longitude to the other osculating elements of the Titan ephemeris. This enables us to develop new synthetic representations that combine the strengths of both approaches: the long-term stability and system complexity inherent in TASS. In our current work, we have shifted our focus to the NOE ephemerides from the Paris Observatory. Unlike the JPL ephemerides and the synthetic TASS ephemerides, the NOE ephemerides account for Saturn’s tidal effects and long-period solar terms within their perturbation calculations. This results in a more complex analytical representation of the NOE ephemeris compared to the JPL ephemeris. Notably, these representations encapsulate crucial dynamical information, including proper frequencies, which are invaluable for theoretical research. http://sedici.unlp.edu.ar:80/handle/10915/192170 Objeto de conferencia IAU Symposium 401 (La Plata, 4 al 9 de agosto de 2025); https://sedici.unlp.edu.ar/handle/10915/190232; IAU Symposium 401: Advancing Reference Systems, Ephemeris, and Standards: from the Earth and the Moon to Solar System Bodies. Book of Abstracts The Bureau International des Poids et Mesures (BIPM) Time department is in charge of the monthly calculation of Coordinated Universal Time (UTC), and its weekly rapid version UTCr. UTC is based on the contribution of about 450 atomic clocks maintained in about 85 time laboratories all over the world compared by means of GNSS, and in some cases by Two-Way Satellite Time and Frequency Transfer. The first step in the computation of UTC is a sort of weighted average of all the clocks to optimize long-term stability. Then the frequency of this average is compared versus the most accurate realization of the second obtained by Primary and Secondary Frequency Standards and a frequency steering is introduced. This process realizes the international atomic time TAI which is a realization of TT as currently defined by IAU in Resolution 4 of its XXIst General Assembly. The last step originated from several discussions taking place in the early ’70s at the IAU (XIVth General Assembly 1970), the Bureau International de l'Heure, the Consultative Committee for the Definition of the Second, and the International Telecommunication Union, which decided to maintain UTC and UT1 in pace within one second with the mechanism of the leap seconds: Since the 1st of January 1972, UTC and TAI differ only by an integer number of seconds, chosen so that it remains within 1 second versus the rotational angle of the Earth UT1. This relies on data communicated by the International Earth Rotation and Reference Systems Service (IERS) through its Bulletin C, and finally enables the publication of UTC. In this presentation, we will summarize the main steps in the computation of UTC, the type of clocks used and the techniques for clock comparisons and the ongoing developments based on the research on new optical frequency standards, as well as new clock comparison techniques. Some recent enhancements on the way UTC is disseminated (i.e. the Circular T, as well as downloadable data available from BIPM’s web server, and the effort towards digitalization) will also be presented. Wed, 01 Jan 2025 00:00:00 GMT http://sedici.unlp.edu.ar:80/handle/10915/192170 2025-01-01T00:00:00Z The Bureau International des Poids et Mesures (BIPM) Time department is in charge of the monthly calculation of Coordinated Universal Time (UTC), and its weekly rapid version UTCr. UTC is based on the contribution of about 450 atomic clocks maintained in about 85 time laboratories all over the world compared by means of GNSS, and in some cases by Two-Way Satellite Time and Frequency Transfer. The first step in the computation of UTC is a sort of weighted average of all the clocks to optimize long-term stability. Then the frequency of this average is compared versus the most accurate realization of the second obtained by Primary and Secondary Frequency Standards and a frequency steering is introduced. This process realizes the international atomic time TAI which is a realization of TT as currently defined by IAU in Resolution 4 of its XXIst General Assembly. The last step originated from several discussions taking place in the early ’70s at the IAU (XIVth General Assembly 1970), the Bureau International de l'Heure, the Consultative Committee for the Definition of the Second, and the International Telecommunication Union, which decided to maintain UTC and UT1 in pace within one second with the mechanism of the leap seconds: Since the 1st of January 1972, UTC and TAI differ only by an integer number of seconds, chosen so that it remains within 1 second versus the rotational angle of the Earth UT1. This relies on data communicated by the International Earth Rotation and Reference Systems Service (IERS) through its Bulletin C, and finally enables the publication of UTC. In this presentation, we will summarize the main steps in the computation of UTC, the type of clocks used and the techniques for clock comparisons and the ongoing developments based on the research on new optical frequency standards, as well as new clock comparison techniques. Some recent enhancements on the way UTC is disseminated (i.e. the Circular T, as well as downloadable data available from BIPM’s web server, and the effort towards digitalization) will also be presented. http://sedici.unlp.edu.ar:80/handle/10915/192169 Objeto de conferencia IAU Symposium 401 (La Plata, 4 al 9 de agosto de 2025); https://sedici.unlp.edu.ar/handle/10915/190232; IAU Symposium 401: Advancing Reference Systems, Ephemeris, and Standards: from the Earth and the Moon to Solar System Bodies. Book of Abstracts The work reported here is one of the activities of the International Telecommunication Union - Radiocommunication Sector (ITU-R) Study Group 7 (SG 7) (Science Services), Working Party 7A (WP 7A) (Time Signals and Frequency Standard Emissions). As a result of technical time scale issues raised by Sector Members of the ITU-R. about thirty years ago and a letter from the Director of the Bureau international des poids et mesures (BIPM) to the Secretary General of the ITU in 2000, a new question ITU-R 236/7 on The Future of the Coordinated Universal Time UTC time scale was gen­ erated by WP 7A in 2001. Question 236/7 was structured to address the future definition and use of UTC in the ITU-R. recommendations, and was updated over time [1], Major technical changes to UTC clearly have a potentially significant impact on communications networks, navigation systems, time/frequency distribution systems and virtually all aspects of civil/military timekeeping, In order to better conduct the often-difficult discussions, several events have taken place in the past, coordinated by the ITU, starting with a meeting at the BIPM in Sèvres in 2002, followed by a Colloquium on UTC in Turin in 2003. Then a draft revision of recommendation TF.460 submitted to Radiocommunication Assembly in 2012 (RA-12), which was unsuccessful due to lack of consensus. These were followed by the holding of an ITU-BIPM workshop in Geneva in 2013, preceded by the publication the same year in an ITU News magazine, of various opinions on the question of whether to abolish or not to abolish the leap second in UTC. As a result, divergent views on the evolution of UTC were clearly reflected in the Conference Preparatory Meeting (CPM) report to the World Radiocommunication Conference of 2015 (WRC-15). Things began to evolve in a convergent way after WRC-15, notably with the adoption by the Conférence générale des poids et mesures (CGPM) of two resolutions, one in 2018 On the definition of time scales and one in 2022 On the use and future development of UTC. In the meantime, a MoU was signed by the BIPM and the ITU in 2020. The work was complemented by the release of a substantial report on Time signals to be disseminated by radiocommunication systems [11], followed by the organization of a Special session with the BIPM on Resolution 655 (WRC- 15) during the 2nd ITU Inter-regional Workshop on WRC-23 Preparation, held in Geneva in 2022, Resulting from close collaboration between the BIPM and the ITU, key articles on the future of UTC were published in ITU News magazine in 2023 Indeed, the year 2023 was a significant and decisive year as the ITU unanimously succeeded in achieving the main objective of moving towards a continuous UTC when WRC-23, held in Dubai from 20 November to 15 December, endorsed the BIPM decision on this matter. This led to the revision of Resolution 655 (WRC-15), paving the way for further studies to be carried out by WP 7A, with a view to a possible revision of Recommendation TF.460 that is incorporated by reference in the Radio Regulations. It could potentially include a new code format for the continuous UTC signal to be disseminated and thus be able to end the process of inserting leap seconds into UTC at a date and for a maximum value of the UT1 - UTC difference that will both be defined in a CGPM Resolution in 2026. The medium-term objective of WP 7A on this topic is to complete the draft revision of Recommendation TF.460 and submit it to Study Group 7 for further consideration and approval, with a view to its subsequent adoption by the RA-27 and then by the WRC-27 to be held in 2027, thus implementing Resolution 655 (Rev.WRC-23). Wed, 01 Jan 2025 00:00:00 GMT http://sedici.unlp.edu.ar:80/handle/10915/192169 2025-01-01T00:00:00Z The work reported here is one of the activities of the International Telecommunication Union - Radiocommunication Sector (ITU-R) Study Group 7 (SG 7) (Science Services), Working Party 7A (WP 7A) (Time Signals and Frequency Standard Emissions). As a result of technical time scale issues raised by Sector Members of the ITU-R. about thirty years ago and a letter from the Director of the Bureau international des poids et mesures (BIPM) to the Secretary General of the ITU in 2000, a new question ITU-R 236/7 on The Future of the Coordinated Universal Time UTC time scale was gen­ erated by WP 7A in 2001. Question 236/7 was structured to address the future definition and use of UTC in the ITU-R. recommendations, and was updated over time [1], Major technical changes to UTC clearly have a potentially significant impact on communications networks, navigation systems, time/frequency distribution systems and virtually all aspects of civil/military timekeeping, In order to better conduct the often-difficult discussions, several events have taken place in the past, coordinated by the ITU, starting with a meeting at the BIPM in Sèvres in 2002, followed by a Colloquium on UTC in Turin in 2003. Then a draft revision of recommendation TF.460 submitted to Radiocommunication Assembly in 2012 (RA-12), which was unsuccessful due to lack of consensus. These were followed by the holding of an ITU-BIPM workshop in Geneva in 2013, preceded by the publication the same year in an ITU News magazine, of various opinions on the question of whether to abolish or not to abolish the leap second in UTC. As a result, divergent views on the evolution of UTC were clearly reflected in the Conference Preparatory Meeting (CPM) report to the World Radiocommunication Conference of 2015 (WRC-15). Things began to evolve in a convergent way after WRC-15, notably with the adoption by the Conférence générale des poids et mesures (CGPM) of two resolutions, one in 2018 On the definition of time scales and one in 2022 On the use and future development of UTC. In the meantime, a MoU was signed by the BIPM and the ITU in 2020. The work was complemented by the release of a substantial report on Time signals to be disseminated by radiocommunication systems [11], followed by the organization of a Special session with the BIPM on Resolution 655 (WRC- 15) during the 2nd ITU Inter-regional Workshop on WRC-23 Preparation, held in Geneva in 2022, Resulting from close collaboration between the BIPM and the ITU, key articles on the future of UTC were published in ITU News magazine in 2023 Indeed, the year 2023 was a significant and decisive year as the ITU unanimously succeeded in achieving the main objective of moving towards a continuous UTC when WRC-23, held in Dubai from 20 November to 15 December, endorsed the BIPM decision on this matter. This led to the revision of Resolution 655 (WRC-15), paving the way for further studies to be carried out by WP 7A, with a view to a possible revision of Recommendation TF.460 that is incorporated by reference in the Radio Regulations. It could potentially include a new code format for the continuous UTC signal to be disseminated and thus be able to end the process of inserting leap seconds into UTC at a date and for a maximum value of the UT1 - UTC difference that will both be defined in a CGPM Resolution in 2026. The medium-term objective of WP 7A on this topic is to complete the draft revision of Recommendation TF.460 and submit it to Study Group 7 for further consideration and approval, with a view to its subsequent adoption by the RA-27 and then by the WRC-27 to be held in 2027, thus implementing Resolution 655 (Rev.WRC-23). http://sedici.unlp.edu.ar:80/handle/10915/192167 Objeto de conferencia IAU Symposium 401 (La Plata, 4 al 9 de agosto de 2025); https://sedici.unlp.edu.ar/handle/10915/190232; IAU Symposium 401: Advancing Reference Systems, Ephemeris, and Standards: from the Earth and the Moon to Solar System Bodies. Book of Abstracts These last years have seen a renewed interest for lunar missions. Would it be for scientific applications, navigation, or communication on the Lunar surface, a lunar standard reference time scale should be defined. Consider­ ing the difference of gravitational potential around the Moon or around the Earth, as well as their different motions in an inertial frame, the Einstein gen­ eral relativity theory predicts of course that the time measured on Earth and that measured on the Moon will not coincide. For example, an ideal clock on the Moon surface, when compared to an ideal clock on Earth surface, would exhibit a 58.7 μs/d drift plus some pseudo-periodic variations, which will be impossible to ignore for most practical purposes. It is therefore difficult to use UTC directly as the reference time scale in the cislunar environment, and space missions’ designers are asking for a practical time scale that would be used as the reference time scale in this environment. The IAU resolution II (2024) recommends constructing a Lunar Celestial Reference System (LCRS), with its time coordinate designated Lunar Coor­ dinate Time (TCL), using the same techniques as to construct the OCRS and TCG, and keeping the unit of measurement of TCL consistent with the SI second. In its resolution III (2024), the IAU also recommends that "the relationships between the possible versions of a lunar reference time scale and other time scales, in particular a lunar coordinate time and UTC, are pursued in a collaborative agreement among the relevant international organizations". One of these is the Consultative Committee for Time and Frequency (CCTF), a sub-committee of the International Committee for Weight and Measures (CIPM). CCTF experts and members of the national metrological institutes in close contact with space agencies started elaborating a strategy to work actively towards a consensus. In this presentation, we will provide a review of the relativistic time scales in the Solar System, and how a new reference scale should be considered for lunar applications considering the IAU recommendations. In particular, we will investigate the possibility of scaling TCL which would allow to remove secular deviation between the lunar time reference and UTC, or between the lunar time reference and the natural time of a clock at the lunar surface. We will analyse the theoretical and practical advantages and drawbacks of the different options for a lunar reference time scale. We will then propose a scheme for the realisation of a lunar reference time, for both the situation where only Earth clocks are available to provide this reference, and the situation where one or more clocks are on the Moon. And we will propose some practical implementation to maintain the traceability of a lunar reference time to UTC. Wed, 01 Jan 2025 00:00:00 GMT http://sedici.unlp.edu.ar:80/handle/10915/192167 2025-01-01T00:00:00Z These last years have seen a renewed interest for lunar missions. Would it be for scientific applications, navigation, or communication on the Lunar surface, a lunar standard reference time scale should be defined. Consider­ ing the difference of gravitational potential around the Moon or around the Earth, as well as their different motions in an inertial frame, the Einstein gen­ eral relativity theory predicts of course that the time measured on Earth and that measured on the Moon will not coincide. For example, an ideal clock on the Moon surface, when compared to an ideal clock on Earth surface, would exhibit a 58.7 μs/d drift plus some pseudo-periodic variations, which will be impossible to ignore for most practical purposes. It is therefore difficult to use UTC directly as the reference time scale in the cislunar environment, and space missions’ designers are asking for a practical time scale that would be used as the reference time scale in this environment. The IAU resolution II (2024) recommends constructing a Lunar Celestial Reference System (LCRS), with its time coordinate designated Lunar Coor­ dinate Time (TCL), using the same techniques as to construct the OCRS and TCG, and keeping the unit of measurement of TCL consistent with the SI second. In its resolution III (2024), the IAU also recommends that "the relationships between the possible versions of a lunar reference time scale and other time scales, in particular a lunar coordinate time and UTC, are pursued in a collaborative agreement among the relevant international organizations". One of these is the Consultative Committee for Time and Frequency (CCTF), a sub-committee of the International Committee for Weight and Measures (CIPM). CCTF experts and members of the national metrological institutes in close contact with space agencies started elaborating a strategy to work actively towards a consensus. In this presentation, we will provide a review of the relativistic time scales in the Solar System, and how a new reference scale should be considered for lunar applications considering the IAU recommendations. In particular, we will investigate the possibility of scaling TCL which would allow to remove secular deviation between the lunar time reference and UTC, or between the lunar time reference and the natural time of a clock at the lunar surface. We will analyse the theoretical and practical advantages and drawbacks of the different options for a lunar reference time scale. We will then propose a scheme for the realisation of a lunar reference time, for both the situation where only Earth clocks are available to provide this reference, and the situation where one or more clocks are on the Moon. And we will propose some practical implementation to maintain the traceability of a lunar reference time to UTC. http://sedici.unlp.edu.ar:80/handle/10915/192165 Objeto de conferencia IAU Symposium 401 (La Plata, 4 al 9 de agosto de 2025); https://sedici.unlp.edu.ar/handle/10915/190232; IAU Symposium 401: Advancing Reference Systems, Ephemeris, and Standards: from the Earth and the Moon to Solar System Bodies. Book of Abstracts With the standardization of an inertial lunar reference system, the Lunar Celestial Reference System (LCRS) and the accompanying Lunar Coordinate Time TCL) it becomes an important next step to consider the practical applications and use of LCRS. LCRS and the accompanying necessary, but not yet standardized, body-fixed lunar reference system (LRS) that enable operations on and near the surface of the Moon, require interoperability with Earth reference systems. TCL is a coordinate time centered on the Moon analogous to Geocentric Coordinate Time (TCG). Currently there is not a connection between practical times like Barycentric Dynamic Time (TDB), or UTC, or a defined lunar surface time analogous to TT and UTC. Computations using LCRS and TCL remain in the theoretical realm until they can be tied to measured time scales. Current practice for computing position and motion using coordinate systems around the Moon use TDB as a default to connect to UTC for spacecraft and observations that move from Earth to the Moon. Furthermore, current calculations of the lunar orientation angles between LCRS and LRS for body-fixed systems like Mean Earth (ME) and Principal Axis (PA) also use TDB as this is dependent on the rotation rate of the Moon. The practical use of LCRS is to create tracking capabilities, define a lunar-oriented position to find celestial objects and to support a lunar-based navigation system. While many missions have successfully traveled from the Earth to the Moon prior to the adoption of the LCRS, more and more missions are being planned and a standardized coordinated system and time for all the missions to use is becoming necessary. Since missions are initially launched from Earth and then transition to the lunar sphere of influence it is critical to: a) have a defined practical time for LCRS either by determining ing the relationship between TCL and TDB or UTC/TT, or defining a local lunar surface time (e.g. Lunar Time TL or LTC etc.) that can be defined by a real or measured time and/or has some connection to terrestrial time; b) determine a crossover point between the sphere of influence of Earth and the Moon, and c) determine the relationship between LCRS and the body fixed system LRS. With all this in place it is possible to have a standardized system of navigation for the surface and lunar orbit, the ability to track celestial references like navigation stars and planets, and the data necessary to create a lunar navigation system. We will illustrate practical uses for the LCRS, ensuring they are consistent with IAU standards and interoperable with other reference systems. Such uses could include navigation for locations on the surface of the moon using celestial objects (stars and planets), precise coordinates (of stars and planets) in LCRS, and transformation parameters from LCRS to LRS. Wed, 01 Jan 2025 00:00:00 GMT http://sedici.unlp.edu.ar:80/handle/10915/192165 2025-01-01T00:00:00Z With the standardization of an inertial lunar reference system, the Lunar Celestial Reference System (LCRS) and the accompanying Lunar Coordinate Time TCL) it becomes an important next step to consider the practical applications and use of LCRS. LCRS and the accompanying necessary, but not yet standardized, body-fixed lunar reference system (LRS) that enable operations on and near the surface of the Moon, require interoperability with Earth reference systems. TCL is a coordinate time centered on the Moon analogous to Geocentric Coordinate Time (TCG). Currently there is not a connection between practical times like Barycentric Dynamic Time (TDB), or UTC, or a defined lunar surface time analogous to TT and UTC. Computations using LCRS and TCL remain in the theoretical realm until they can be tied to measured time scales. Current practice for computing position and motion using coordinate systems around the Moon use TDB as a default to connect to UTC for spacecraft and observations that move from Earth to the Moon. Furthermore, current calculations of the lunar orientation angles between LCRS and LRS for body-fixed systems like Mean Earth (ME) and Principal Axis (PA) also use TDB as this is dependent on the rotation rate of the Moon. The practical use of LCRS is to create tracking capabilities, define a lunar-oriented position to find celestial objects and to support a lunar-based navigation system. While many missions have successfully traveled from the Earth to the Moon prior to the adoption of the LCRS, more and more missions are being planned and a standardized coordinated system and time for all the missions to use is becoming necessary. Since missions are initially launched from Earth and then transition to the lunar sphere of influence it is critical to: a) have a defined practical time for LCRS either by determining ing the relationship between TCL and TDB or UTC/TT, or defining a local lunar surface time (e.g. Lunar Time TL or LTC etc.) that can be defined by a real or measured time and/or has some connection to terrestrial time; b) determine a crossover point between the sphere of influence of Earth and the Moon, and c) determine the relationship between LCRS and the body fixed system LRS. With all this in place it is possible to have a standardized system of navigation for the surface and lunar orbit, the ability to track celestial references like navigation stars and planets, and the data necessary to create a lunar navigation system. We will illustrate practical uses for the LCRS, ensuring they are consistent with IAU standards and interoperable with other reference systems. Such uses could include navigation for locations on the surface of the moon using celestial objects (stars and planets), precise coordinates (of stars and planets) in LCRS, and transformation parameters from LCRS to LRS. http://sedici.unlp.edu.ar:80/handle/10915/192163 Objeto de conferencia IAU Symposium 401 (La Plata, 4 al 9 de agosto de 2025); https://sedici.unlp.edu.ar/handle/10915/190232; IAU Symposium 401: Advancing Reference Systems, Ephemeris, and Standards: from the Earth and the Moon to Solar System Bodies. Book of Abstracts The study of lunar physical librations is a significant branch of plane­ tary science, like the free modes of the librations are closely related to the Moon’s internal structure, making their study crucial for understanding the Moon’s formation and evolution, Existing analytical representation method merges spectral analysis of numerical ephemerides with an analyti­ cal ephemerides framework, providing a compact solution with greater long­ term stability than numerical approaches and higher accuracy than analytical methods, This work refines analytical representation method by incor­ porating lunar laser ranging data, enabling adjustments of quasi-periodic components and achieving observational residuals at the centimeter scale. This enhancement brings the analytical representations closer to actual observations. Looking ahead, the advanced analytical representation method provides novel perspectives and data support for research on the Moon’s internal structure. Wed, 01 Jan 2025 00:00:00 GMT http://sedici.unlp.edu.ar:80/handle/10915/192163 2025-01-01T00:00:00Z The study of lunar physical librations is a significant branch of plane­ tary science, like the free modes of the librations are closely related to the Moon’s internal structure, making their study crucial for understanding the Moon’s formation and evolution, Existing analytical representation method merges spectral analysis of numerical ephemerides with an analyti­ cal ephemerides framework, providing a compact solution with greater long­ term stability than numerical approaches and higher accuracy than analytical methods, This work refines analytical representation method by incor­ porating lunar laser ranging data, enabling adjustments of quasi-periodic components and achieving observational residuals at the centimeter scale. This enhancement brings the analytical representations closer to actual observations. Looking ahead, the advanced analytical representation method provides novel perspectives and data support for research on the Moon’s internal structure. http://sedici.unlp.edu.ar:80/handle/10915/192162 Objeto de conferencia IAU Symposium 401 (La Plata, 4 al 9 de agosto de 2025); https://sedici.unlp.edu.ar/handle/10915/190232; IAU Symposium 401: Advancing Reference Systems, Ephemeris, and Standards: from the Earth and the Moon to Solar System Bodies. Book of Abstracts Despite achieving sub-milliarcsecond per-source position accuracies and an overall celestial reference frame (CRF) stability of a few tens of micro­ arcseconds, consistent source positions and frame orientations across wave­ lengths has not yet been achieved, hampering the goal of producing a wave­ length-independent CRF. Source position discrepancies are seen both between radio frequencies (e.g., X and K) and between the radio and the optical CRFs (i.e., ICRF3 and Gaia-CRF3), with about 15% of ICRF3 sources having statistically significant optical-radio position offsets. It has recently been shown by the U.S. Naval Observatory that the prevalence of optical-radio position offsets is inversely correlated with photometric variability, strongly indicating blazars as astrometrically stable sources. In this presentation, I review important recent results on the relationship between blazars and multi-wavelength astrometric stability and argue that blazars should be the object of choice for the next ICRF and future geodetic observations. Wed, 01 Jan 2025 00:00:00 GMT http://sedici.unlp.edu.ar:80/handle/10915/192162 2025-01-01T00:00:00Z Despite achieving sub-milliarcsecond per-source position accuracies and an overall celestial reference frame (CRF) stability of a few tens of micro­ arcseconds, consistent source positions and frame orientations across wave­ lengths has not yet been achieved, hampering the goal of producing a wave­ length-independent CRF. Source position discrepancies are seen both between radio frequencies (e.g., X and K) and between the radio and the optical CRFs (i.e., ICRF3 and Gaia-CRF3), with about 15% of ICRF3 sources having statistically significant optical-radio position offsets. It has recently been shown by the U.S. Naval Observatory that the prevalence of optical-radio position offsets is inversely correlated with photometric variability, strongly indicating blazars as astrometrically stable sources. In this presentation, I review important recent results on the relationship between blazars and multi-wavelength astrometric stability and argue that blazars should be the object of choice for the next ICRF and future geodetic observations. http://sedici.unlp.edu.ar:80/handle/10915/192161 Objeto de conferencia IAU Symposium 401 (La Plata, 4 al 9 de agosto de 2025); https://sedici.unlp.edu.ar/handle/10915/190232; IAU Symposium 401: Advancing Reference Systems, Ephemeris, and Standards: from the Earth and the Moon to Solar System Bodies. Book of Abstracts On this work we will show the past 10 years of CART (China Argentina Radio Telescope) evolution, especially related to construction activities. We explain current assembly status and receiver integrations. Finally, we detail the development of digital wide band back end to be integrated with the future receivers. Wed, 01 Jan 2025 00:00:00 GMT http://sedici.unlp.edu.ar:80/handle/10915/192161 2025-01-01T00:00:00Z On this work we will show the past 10 years of CART (China Argentina Radio Telescope) evolution, especially related to construction activities. We explain current assembly status and receiver integrations. Finally, we detail the development of digital wide band back end to be integrated with the future receivers.