Zinovy Malkin

Pulkovo Observatory · Radio astronomy research

In many astronomical works, the structure of vector fields is analyzed, such as the differences in the celestial object coordinates in catalogs or the celestial object velocities, by decomposition into vector spherical harmonics (VSH). This method has shown high efficiency in many studies, but, at the same time, comparing the results obtained by di...

Pulkovo Observatory has been operating a permanent GNSS station PULK since 2002. This paper presents the results of preliminary analysis of the changes in the errors in the coordinates of the station over time, primarily after replacement of the receiver or antenna. Two accuracy estimates were applied: the formal error of the daily coordinate estim...

The International Celestial Reference Frame (ICRF) based on the VLBI-derived positions of 608 extragalactic radio sources was adopted by the International Astronomical Union (IAU) in 1998 as the first realization of the International Celestial Reference System (ICRS). Later, in 2009 and 2020, two extended ICRF versions, ICRF2 and ICRF3, respectivel...

Recently published studies suggested that the difference between Universal and Coordinated Time UT1-UTC could reach a large positive value in a few years, making it necessary to introduce a negative leap second into the UTC scale for the first time in its history. Based on the latest UT1 series provided by the International Earth Rotation and Refer...

The prediction of the Earth’s rotation parameters, including the coordinates of the celestial pole (precession-nutation angles), is necessary for many practical applications. This work is devoted to the study of changes in the accuracy of the prediction of precession-nutation angles over time over the past 16 years. This study was conducted on the...

The paper analyzes the real predictions of the Earth's rotation parameters (ERP) made in the Russian State Service of the Earth's Rotation (the Center for processing and analyzing data on the parameters of the Earth's rotation of the Main Metrological Center of the State Service of Time, Frequency and Determination of the Parameters of the Earth's...

Galactic aberration in proper motions (GA) has an amplitude (also known as the Galactic aberration constant) of about 5 µas/yr, which is substantial for the modern highly accurate astrometric observations such as Gaia and radio astrometry. There are several determination of the GA constant, but they don’t agree well. The estimates derived from radi...

In this paper, optical magnitudes of astrometric radio sources from the OCARS catalog measured with ground-based telescopes and by Gaia space telescope have been compared. It was found that for some sources these magnitudes agree well, while other sources show significant disagreement. The disagreement is mostly observed for extended Galaxies for w...

The paper is devoted to the analysis of two components of the Earth’s rotation, Chandler wobble (CW) and free core nutation (FCN). They are oscillations with near-constant periods but variable amplitude and phase. The variations of the amplitude and phase of the CW and FCN have already been considered in the literature, and both showed similar beha...

Major results of researches conducted by Russian geodesists in 2019–2022 on the topics of the International Association of Geodesy (IAG) of the International Union of Geodesy and Geophysics (IUGG) are presented in this issue. This report is prepared by the Section of Geodesy of the National Geophysical Committee of Russia. In the report prepared fo...

Galactic aberration (GA) is a small effect in proper motions of celestial objects with an amplitude of about 5 μ as yr ⁻¹ already noticeable in highly accurate astrometric observations such as VLBI and Gaia. However accurate accounting for this effect faces difficulty caused by the uncertainty in the GA amplitude (GA constant). Its estimates derive...

A new method SREAG (Spherical Rectangular Equal-Area Grid) was proposed in Malkin (2019) to divide a spherical surface into rectangular cells of equal area. SREAG grid consists of a set of rings parallel to the equator, and each ring is divided into several cells, the number of which depends on the mean latitude of the ring. This paper presents som...

The OCARS catalog (Optical Characteristics of Astrometric Radio Sources) is a compiled catalog of various additional data related to astrometric radio sources, that is, objects whose coordinates are determined from VLBI observations. It contains the source coordinates in the radio and optical bands, object type, redshift, photometric data in the op...

Aims. In this study, we compare several methods of modeling large-scale systematic differences between catalogs of positions of extragalactic radio sources provided by very long baseline interferometry with an emphasis on mitigating the impact of outliers. Methods. The coordinate difference between catalogs was parameterized by first and second ord...

We announce the detection of a new large jump in the phase of the free core nutation (FCN). This is only the second such large FCN phase jump in more than thirty years of FCN monitoring by means of a very long baseline interferometry (VLBI) technique. The new event was revealed and confirmed by analyzing two FCN models derived from a long-time seri...

Aims. At the beginning of 2019 the third realization of the International Celestial Reference Frame (ICRF3) replaced the previous version (ICRF2). In the current International Celestial Reference Frame (ICRF), a major improvement is the inclusion of the Galactic aberration (GA) effect. The Earth orientation parameters (EOP), which link the celestia...

The understanding of forced temporal variations in celestial pole motion (CPM) could bring us significantly closer to meeting the accuracy goals pursued by the Global Geodetic Observing System (GGOS) of the International Association of Geodesy (IAG), i.e., 1 mm accuracy and 0.1 mm/year stability on global scales in terms of the Earth orientation pa...

The seasonal signal determined by the Global Navigation Satellite System (GNSS) which 18 is captured in the coordinate time series, exhibits annual and semi-annual periods. This signal is 19 frequently modeled by two periodic signals with constant amplitude and phase-lag. The purpose 20 of this study is to explore the implication of different types...

An analysis of the source position differences between very long baseline interferometry-based ICRF and Gaia-celestial reference frame catalogues is a key step in assessing their systematic errors and determining their mutual orientation. One of the main factors that limits the accuracy of determination of the orientation parameters between two fra...

An analysis of the source position differences between VLBI-based ICRF and $Gaia$-CRF catalogues is a key step in assessing their systematic errors and determining their mutual orientation. One of the main factors that limits the accuracy of determination of the orientation parameters between two frames is the impact of outliers. To mitigate this e...

Despite continuous increasing of the number of ICRF sources, their sky coverage is still not satisfactory. The goal of this study is to discuss some new considerations for extending the ICRF source list. Statistical analysis of the ICRF catalog allows us to identify less populated sky regions where new ICRF sources or additional observations of the...

A comparison was made between $Gaia$ magnitudes and magnitudes obtained from ground-based observations for astrometric radio sources . The comparison showed that these magnitudes often not agree well. There may be several reasons for this disagreement. Nevertheless, such an analysis can serve as an additional filter for verification of the object c...

The final clock product provided by the IGS (International GNSS Service) with a 30/300 s sampling interval for satellites and stations respectively is characterized by accuracy of 75 ± 20 ps RMS (Root Mean Square). Since mid-2012, the MGEX (Multi-GNSS Experiment) experiment provides full products containing all available GNSS (Global Navigation Sat...

A new realization of the International Celestial Reference Frame (ICRF) is presented based on the work achieved by a working group of the International Astronomical Union (IAU) mandated for this purpose. This new realization, referred to as ICRF3, is based on nearly 40 years of data acquired by very long baseline interferometry. The ICRF3 includes...

A new realization of the International Celestial Reference Frame (ICRF) is presented based on the work achieved by a working group of the International Astronomical Union (IAU) mandated for this purpose. This new realization follows the initial realization of the ICRF completed in 1997 and its successor, ICRF2, adopted as a replacement in 2009. The...

2019 marked the 20th anniversary of the International VLBI Service for Geodesy and Astrometry (IVS). This service is the largest and most authoritative organization that coordinates international activities in radio astrometry and VLBI sub-system of space geodesy. Currently, about 60 antennas located in many countries on all continents participate...

Lidia Dmitrievna Kostina and Natalia Romanovna Persiyaninova left a bright mark in the history of the Pulkovo Observatory, as well as in the history of the domestic and international latitude services. In the first place, they were absolute leaders in the latitude observations with the famous zenith telescope ZTF-135. In 1954-2001, they obtained to...

A new method Spherical Rectangular Equal-Area Grid (SREAG) was proposed in Malkin (2019) for splitting spherical surface into equal-area rectangular cells. In this work, some more detailed features of SREAG are presented. The maximum number of rings that can be achieved with SREAG for coding with 32-bit integer is $N_{ring}$=41068, which correspond...

A new method SREAG (spherical rectangular equal-area grid) is proposed to divide a spherical surface into equal-area cells. The method is based on dividing a sphere into latitudinal rings of near-constant width with further splitting of each ring into equal-area cells. It is simple in construction and use, and provides more uniform width of the lat...

A new method SREAG (spherical rectangular equal-area grid) is proposed to divide a spherical surface into equal-area cells. The method is based on dividing a sphere into latitudinal rings of near-constant width with further splitting each ring into equal-area cells. It is simple in construction and use, and provides more uniform width of the latitu...

In this National Report are given major results of researches conducted by Russian geodesists in 2015-2018 on the topics of the International Association of Geodesy (IAG) of the International Union of Geodesy and Geophysics (IUGG). This report is prepared by the Section of Geodesy of the National Geophysical Committee of Russia. In the report prepa...

In this National Report are given major results of researches conducted by Russian geodesists in 2015–2018 on the topics of the International Association of Geodesy (IAG) of the International Union of Geodesy and Geophysics (IUGG). This report is prepared by the Section of Geodesy of the National Geophysical Committee of Russia. In the report prepa...

Aims. The IVS Working Group on Galactic Aberration (WG8) was established to investigate issues related to incorporating the effect of Galactic aberration in IVS analysis. The circular motion of the solar system barycenter around the Galactic center causes a change in aberration, which in the case of geodetic VLBI observing is over time scales of se...

IAU Commission 19 began in 1919 with the birth of the IAU at the Brussels Conference, where Standing Committee 19 on Latitude Variations was established as one of 32 standing committees. At the first IAU General Assembly in 1922, Standing Committee 19 became Commission 19 “Variation of Latitude”. In the beginning, the main topic of the Commission w...

A new version of the Optical Characteristics of Astrometric Radio Sources (OCARS) catalog is presented. This compiled catalog includes radio sources observed in different VLBI programs and experiments that result in source position determination, their redshift, and photometry in the visible and near-infrared bands. A cross-identification table bet...

A new version of the OCARS (Optical Characteristics of Astrometric Radio Sources) catalog is presented. This compiled catalog includes radio sources observed in different VLBI programs and experiments that result in source position determination, their redshift and photometry in the visible and near-infrared bands. A cross-identification table betw...

The link problem between radio (VLBI/ICRF) and optical (Gaia/GCRF) celestial reference frames is analyzed. Both systems should be a realization of the ICRS (International Celestial Reference System) at microarcsecond level of accuracy. Therefore, the link between the ICRF and GCRF should be obtained with similar accuracy, which is not a trivial tas...

The third realisation of the International Celestial Reference Frame (ICRF-3) is based on high precision Very Long Baseline Interferometric (VLBI) measurements of positions of 4,588 extra-galactic radio sources and 4,536 sources of them are observed at 2.3 and 8.4 GHz. This includes the 303 defining sources which determine the orientation of the fr...

The International Celestial Reference Frame (ICRF) is currently realized by the very long baseline interferometry (VLBI) observations of extragalactic sources with the zero proper motion assumption, while Gaia will observe proper motions of these distant and faint objects to an accuracy of tens of microarcseconds per year. This paper investigates t...

The paper deals with the relative coordinate-and-time determination in a ground based reference frame by using the NAVSTAR/GLONASS radio interferometry and duplex clock comparison techniques.

A new method is proposed to divide a spherical surface into equal-area cells. This method is based on dividing a sphere into several latitudinal bands of near-constant span with further division of each band into equal-area cells. It is simple in construction and provides more uniform latitude step between the latitudinal bands than other simple me...

A new version of the Optical Characteristics of Astrometric Radio Sources (OCARS) catalog is presented. The catalog includes a list of radio sources observed in astrometric and geodetic VLBI programs since 1979, their redshifts, photometric data in 13 bands in the visible and near infrared, and a table indicating identifications btween the OCARS ob...

Three combined celestial pole offset (CPO) series computed at the Paris Observatory (C04), the United States Naval Observatory (USNO), and the International VLBI Service for Geodesy and Astrometry (IVS), as well as six free core nutation (FCN) models, were compared from different perspectives, such as stochastic and systematic differences, and FCN...

The current state of the link problem between radio and optical celestial reference frames is considered. The main objectives of the investigations in this direction during the next few years are the preparation of a comparison and the mutual orientation and rotation between the optical Gaia Celestial Reference Frame (GCRF) and the 3rd generation r...

The International VLBI Service for Geodesy and Astrometry (IVS) regularly produces high-quality Earth orientation parameters from observing sessions employing extensive networks or individual baselines. The master schedule is designed according to the telescope days committed by the stations and by the need for dense sampling of the Earth orientati...

A possible method for linking the optical Gaia Celestial Reference Frame (GCRF) to the VLBI-based International Celestial Reference Frame (ICRF) is to use radio stars in a manner similar to that in the linking of the Hipparcos Celestial Reference Frame (HCRF) to ICRF. In this work, an obtainable accuracy of the orientation angles between GCRF and I...

One of the possible strategies for linking the optical Gaia Celestial Reference Frame (GCRF) to the VLBI-based International Celestial Reference Frame (ICRF) is using radio stars in a manner similar to that used for linking HIPPARCOS Celestial Reference System (HCRF) to ICRF. A reachable precision of the orientation angles between GCRF and ICRF fra...

The Allan variance (AVAR) was introduced 50 years ago as a statistical tool for assessing of the frequency standards deviations. For the past decades, AVAR has increasingly being used in geodesy and astrometry to assess the noise characteristics in geodetic and astrometric time series. A specific feature of astrometric and geodetic measurements, as...

This paper contains a brief review of the Russian geodesists’ activity in 2011–2014 in the field of geodynamics mainly based on the analysis of the literature on the subject. The main research topics were investigations of active tectonic regions in Russia and surrounding regions such as Fennoscandia, Baltic Region, North Caucasus, Far East, Baikal...

This report contains a brief review of the Russian geodesists’ activity in 2011–2014 in the field of general geodesy and related problems mainly based on the analysis of the literature on the subject. Various questions of the geodesy theory and applications were considered. Different aspects of interaction between geodesy, astronomy, and other scie...

This paper contains a brief review of the Russian geodesists’ activity in 2011–2014 in the field of reference frames mainly based on the analysis of the literature on the subject. The main research topics were improvement of ITRF and Russian Fundamental Astro-Geodetic Network (FAGN) as well as height and gravimetric networks. Also considered were I...

The highly-accurate optical reference frame GCRF (Gaia Celestial Reference Frame) is expected to be available in several years. By the same time, a new version of radio reference frame ICRF (International Celestial Reference Frame) will be also published. The link of GCRF to ICRF will be defined by means of computation of the orientation angles bet...

Variations in free core nutation (FCN) are connected with various processes in the Earth's fluid core and core-mantle coupling, which are also largely responsible for the geomagnetic field variations, particularly the geomagnetic jerks (GMJs). A previous study (Malkin, 2013) revealed that the epochs of the observed extremes in the FCN amplitude and...

The activities and some research progress of IAU Commission 19 (C19)-Rotation of the Earth-in the past triennial term (2012-2015) is reported in this paper, including the scientific session and business meeting of C19, as well as a business meeting of the IAU/IAG Joint Working Group of Theory of Earth Rotation (JWG-ThER) during the XXIX IAU General...

We present the second realization of the International Celestial Reference Frame (ICRF2) at radio wavelengths using nearly 30 years of Very Long Baseline Interferometry observations. ICRF2 contains precise positions of 3414 compact radio astronomical objects and has a positional noise floor of ~40 μas and a directional stability of the frame axes o...

We present the second realization of the International Celestial Reference Frame (ICRF2) at radio wavelengths using nearly 30 years of Very Long Baseline Interferometry observations. ICRF2 contains precise positions of 3414 compact radio astronomical objects and has a positional noise floor of ~40 μas and a directional stability of the frame axes o...

The future ICRF3 realisation is discussed here

The increasing accuracy and growing time span of Very Long Baseline Interferometry (VLBI) observations allow the determination of seasonal signals in station positions which still remain unmodelled in conventional analysis approaches. In this study we focus on the impact of the neglected seasonal signals in the station displacement on the celestial...

Source position time series produced by International VLBI Service for Geodesy and astrometry (IVS) Analysis Centers were analyzed. These series was computed using different software and analysis strategy. Comparison of this series showed that they have considerably different scatter and systematic behavior. Based on the inspection of all the serie...

Very Long Baseline Interferometry (VLBI) is a primary space-geodetic technique for determining precise coordinates on the Earth, for monitoring the variable Earth rotation and orientation with highest precision, and for deriving many other parameters of the Earth system. The International VLBI Service for Geodesy and Astrometry (IVS, http://ivscc.g...

This is an erratum to the paper 'On the implications of the Galactic aberration in proper motions for celestial reference frame' published in MNRAS 445, 845 (2014). As was pointed out by Wallace (private communication), the text related to matrix (5) is, strictly speaking, not fully accurate and needs clarification.

In this paper 1 , a list of apparent close approaches of Jupiter and Saturn to the geodetic radio sources for the years 2008-2050 has been obtained making use of the EPOS software package. We have found 79 events with distance tolerance of 10 ′ , including four occultations of radio sources by Jupiter and one occultation by the Saturn's ring.

We propose a 3rd generation radio-based International Celestial Reference Frame (ICRF-3) to improve upon the highly successful ICRF-2. Our goals are to improve the precision as well as the spatial and frequency coverages relative to the ICRF-2 by 2018. This date is driven by the desire to create radio frames early enough to test the Gaia optical fr...

The goal of this presentation is to report the latest progress in creation of the next generation of VLBI-based International Celestial Reference Frame, ICRF3. Two main directions of ICRF3 development are improvement of the S/X-band frame and extension of the ICRF to higher frequencies. Another important task of this work is the preparation for com...

This article introduces application of the commensurability revealed by Titius-Bode Law in earthquake (EQ) prediction study. The results show that occurrence of the most of the world's major earthquakes is not accidental, and they occurred at the commensurable points of time axis. As an example, both EQ 7.0 in Lushan, China on 2013{04{20 and EQ 8.2...

During the last few years, much attention has been paid to the astrometric implications of the galactic aberration in proper motions (GA). This effect causes systematic errors in astrometric measurements at a μas level. Some authors consider it so serious that it requires redefinition of the Celestial Reference Frame (CRF). We argue that such atten...

In this paper we outline several problems related to the realization of the international celestial and terrestrial reference frames ICRF and ITRF at the millimeter level of accuracy, with emphasis on ICRF issues. The main topics considered are: analysis of the current status of the ICRF, mutual impact of ICRF and ITRF, and some considerations for...

Corrections to the IAU 2000/2006 parameters of the theory of precession and nutation are calculated using five different series—two individual series and three combined series that have been used in the literature for this purpose. A comparison of the sets of corrections obtained using the different datasets indicates significance systematic differ...

Software used in the Laboratory of Space Geodesy and Earth Rotation (LSGER) of the Institute of Applied Astronomy (IAA) of the Russian Academy of Sciences for computation of geodynamical products: Earth Orientation Parameters (EOP) and station coordinates (TRF) based on observations of space geodesy techniques (VLBI, SLR) is described. The principa...

In this paper, an attempt is made to extract a systematic part from the source apparent motions obtained from the position time series provided by nine IVS Analysis Centers in the framework of the ICRF-2 project. Our preliminary results show that the radio source velocities and the parameters of the systematic part of the velocity field differ subs...

According to the decision of the International Astronomical Union (IAU), since 1998 the International Celestial Reference System has been realized by the ICRF catalogue of extragalactic radio source positions obtained from VLBI observations. Over the past years, the accuracy of the ICRF catalogue data has been increased only through an increase in...

In this study, we compared results of determination of the orientation angles between celestial reference frames realized by radio source position catalogues using three methods of accounting for correlation information: using the position errors only, using additionally the correlations be-tween the right ascension and declination (RA/DE correlati...

The ICRF-3: Status, plans, and progress on the next generation celestial reference frame Christopher S. Jacobs and the ICRF-3 Working group Jet Propulsion Laboratory, California Institute of Technology ICRF-3 seeks to improve upon the highly successful ICRF-2. Our goals are to improve the precision, spatial and frequency coverage relative to the...

The main body of the paper deals with the problem of establishing and developing the Regional Terrestrial Reference Frame for North East Eurasia (North East Eurasia Reference Frame - NEEREF). The problem solving suggests the creation of the International Scientific Organization. The initiative for establishment of the International Commission on th...

In this presentation, several publicly available empiric models of the celestial pole offset (CPO) and free core nutation (FCN), included those developed by the author, are investigated and compared each other from different points of view, such as representation of the observation data, FCN parameters variation, prediction accuracy. Based on this...

In this paper we outline several problems related to the realization of the international celestial and terrestrial reference frames --- the ICRF and ITRF --- at the millimeter level of accuracy, with emphasis on ICRF issues. We consider here the current status of the ICRF, the interrelationship between the ICRF and ITRF, and considerations for fut...

In this paper, a new method of investigation of the external radio source position catalogs RSPCs stochastic errors is presented. Using this method the stochastic errors of nine recently published RSPCs were evaluated. It has been shown that the result can be affected by the systematic differences between catalogs if the latter are not accounted fo...

Although the calculation of the weighted mean of several individual values (one of the most frequently used operations in scientific analysis) is straightforward, the calculation of the corresponding uncertainty does not always receive the attention it requires. The application of methods of classical statistics to real observational data is often...

Allan Variance (AVAR) was introduced more than 40 years ago as an estimator of the stability of frequency standards. Now it is also used for investigations of time series in astronomy and geodesy. However, there are several issues with this method that need special consideration. First, unlike frequency measurements, astronomical and geodetic time...

Assessing the external stochastic errors of radio source position catalogues derived from VLBI observations is important for tasks such as estimating the quality of the catalogues and their weighting during combination. One of the widely used methods to estimate these errors is the three-cornered-hat technique, which can be extended to the N-corner...

Several attempts to discover the FICN signal in VLBI nutation series made during last years failed. In this paper, we present some results of our further steps in this direction, unfortunately not successful either. We investigated several VLBI CPO series by means of spectral and wavelet analysis. It has been shown that there are several periodic s...

In this work, we analyzed all available determinations of the Galactic rotation parameters $R_0$ and $\Omega_0$ made during last 10 years to derive the most probable value of the Galactic aberration constant $A = R_0 \Omega_0^2/c$. We used several statistical methods to obtain reliable estimates of $R_0$ and $\Omega_0$ and their realistic errors. I...

International Commission on Regional Terrestrial Reference Frame of North East Eura-sia (North East Eurasia Reference Frame - NEEREF) is organising by the initiative of the Geodesy Section of the National Geophysical Committee of Russian Academy of Sciences. It is voluntary association of the organisations of various form of ownership and of the va...

Based on several tens of Ro measurements made during the past decades, several studies have been performed to derive the best estimate of Ro. Some used just simple averaging to derive a result, whereas others provided comprehensive analyses of possible errors in published results. In either case, detailed statistical analyses of data used were not...

In this paper, the method of Singular Spectrum Analysis (SSA) is applied for investigation of the zenith troposphere delay time-series derived from VLBI observations. With the help of this method we can analyze the structure of time-series and separate the harmonic and irregular (trend) components. Combined IVS time-series of zenith wet and total t...

UT1 estimates obtained from the very long baseline interferometry (VLBI) Intensives data depend on the station displacement model used during processing. In particular, because of seasonal variations, the instantaneous station position during the specific intensive session differs from the position predicted by the linear model generally used. This...

icrf2.dat 3414x136 ICRF2 catalog; tn35.pdf 9516x512 PDF version of the paper

A new method has been developed at the Siberian Research Institute of Metrology (SNIIM) for highly accurate prediction of UT1 and Pole coordinates. The method is based on construction of a general polyharmonic model of the variations of the Earth rotation parameters using all the data available for the last 80-100 years, and modified autoregression...

Radio astronomy observations of close approaches of the Solar system planets to compact radio sources as well as radio source occultations by planets may be of large interest for planetary sciences, dynamical astronomy, and testing gravity theories. In this paper, we present extended lists of occultations of astrometric radio sources observed in th...