Determination of the reference frames deflections from optical observations of GNSS satellites

Optical observations of navigation satellites were carried out at Terskol observatory during 2007-2010 with the aim to determine the deffection angles between GPS and GLONASS dynamical reference frames. There were three different observations strategies: celestial equator crossing, intersection of v...

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Published in:Advances in Astronomy and Space Physics
Date:2011
Main Authors: Choliy, V.Ya., Zhaborovskyy, V.P., Taradiy, V., Rykhlova, L.
Format: Article
Language:English
Published: Головна астрономічна обсерваторія НАН України 2011
Online Access:https://nasplib.isofts.kiev.ua/handle/123456789/119092
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Journal Title:Digital Library of Periodicals of National Academy of Sciences of Ukraine
Cite this:Determination of the reference frames deflections from optical observations of GNSS satellites / V.Ya. Choliy, V.P. Zhaborovskyy, V. Taradiy, L. Rykhlova // Advances in Astronomy and Space Physics. — 2011. — Т. 1., вип. 1-2. — С. 99-101. — Бібліогр.: 7 назв. — англ.

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Digital Library of Periodicals of National Academy of Sciences of Ukraine
id nasplib_isofts_kiev_ua-123456789-119092
record_format dspace
spelling Choliy, V.Ya.
Zhaborovskyy, V.P.
Taradiy, V.
Rykhlova, L.
2017-06-03T20:14:19Z
2017-06-03T20:14:19Z
2011
Determination of the reference frames deflections from optical observations of GNSS satellites / V.Ya. Choliy, V.P. Zhaborovskyy, V. Taradiy, L. Rykhlova // Advances in Astronomy and Space Physics. — 2011. — Т. 1., вип. 1-2. — С. 99-101. — Бібліогр.: 7 назв. — англ.
987-966-439-367-3
https://nasplib.isofts.kiev.ua/handle/123456789/119092
Optical observations of navigation satellites were carried out at Terskol observatory during 2007-2010 with the aim to determine the deffection angles between GPS and GLONASS dynamical reference frames. There were three different observations strategies: celestial equator crossing, intersection of visible satellite paths, occultation of astrometric stars with the satellite. We present methodology of observation, data processing and the first results.
Authors kindly acknowledge M. Andreev from Terskol observatory for his help in optical observations.
en
Головна астрономічна обсерваторія НАН України
Advances in Astronomy and Space Physics
Determination of the reference frames deflections from optical observations of GNSS satellites
Article
published earlier
institution Digital Library of Periodicals of National Academy of Sciences of Ukraine
collection DSpace DC
title Determination of the reference frames deflections from optical observations of GNSS satellites
spellingShingle Determination of the reference frames deflections from optical observations of GNSS satellites
Choliy, V.Ya.
Zhaborovskyy, V.P.
Taradiy, V.
Rykhlova, L.
title_short Determination of the reference frames deflections from optical observations of GNSS satellites
title_full Determination of the reference frames deflections from optical observations of GNSS satellites
title_fullStr Determination of the reference frames deflections from optical observations of GNSS satellites
title_full_unstemmed Determination of the reference frames deflections from optical observations of GNSS satellites
title_sort determination of the reference frames deflections from optical observations of gnss satellites
author Choliy, V.Ya.
Zhaborovskyy, V.P.
Taradiy, V.
Rykhlova, L.
author_facet Choliy, V.Ya.
Zhaborovskyy, V.P.
Taradiy, V.
Rykhlova, L.
publishDate 2011
language English
container_title Advances in Astronomy and Space Physics
publisher Головна астрономічна обсерваторія НАН України
format Article
description Optical observations of navigation satellites were carried out at Terskol observatory during 2007-2010 with the aim to determine the deffection angles between GPS and GLONASS dynamical reference frames. There were three different observations strategies: celestial equator crossing, intersection of visible satellite paths, occultation of astrometric stars with the satellite. We present methodology of observation, data processing and the first results.
isbn 987-966-439-367-3
url https://nasplib.isofts.kiev.ua/handle/123456789/119092
citation_txt Determination of the reference frames deflections from optical observations of GNSS satellites / V.Ya. Choliy, V.P. Zhaborovskyy, V. Taradiy, L. Rykhlova // Advances in Astronomy and Space Physics. — 2011. — Т. 1., вип. 1-2. — С. 99-101. — Бібліогр.: 7 назв. — англ.
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fulltext Determination of the reference frames de�ections from optical observations of GNSS satellites Choliy V. Ya.1, Zhaborovskyy V. P.1, Taradiy V.2, Rykhlova L.2 1 Taras Shevchenko National University of Kyiv, Glushkova ave., 4, 03127, Kyiv, Ukraine 2INASAN, Pyatnizkaya st., 48, 119017, Moscow, Russia charlie@univ.kiev.ua Optical observations of navigation satellites were carried out at Terskol observatory during 2007-2010 with the aim to determine the de�ection angles between GPS and GLONASS dynamical reference frames. There were three di�erent observations strategies: celestial equator crossing, intersection of visible satellite paths, occultation of astrometric stars with the satellite. We present methodology of observation, data processing and the �rst results. Introduction During seasons of 2007-2010 optical observation of navigation (GPS and GLONASS) satellites were carried out at Terskol observatory (3128 m above sea level, Northern Caucasus, Russia). In total, more than 3000 raw satellite images were caught. The �rst testing images have 5 sec exposure while the most of others � 1 sec. Raw images served as a sources of combined ones. Examples are presented in Fig. 1. Figure 1: Three kinds of observations (left to right): equator crossing, reference star occultation, mutual paths crossing. Three di�erent types of events were interesting for us. First of all if there was a visible satellite path crossing with celestial equator (left part of Fig. 1). Such events may be easily forecasted. Processing of the pictures consists in �xing the place on the equator where the satellite crossed it. Sometimes, the satellite occults reference astrometric star (central part of Fig. 1). As the star is a point-like source it is very di�cult to forecast such events. That is why they were observed mostly occasionally. The third type of events was visible intersection of satellite paths (right part of Fig. 1). It is quite possible, as inclinations of GPS and GLONASS orbits are di�erent. The mutual intersections are quite rare: 1− 2 observable events per night. The last type of events needs very precise ephemeris. Good example is presented on the right part of Fig. 1. According to ephemeris we planed to catch the intersection near the center of telescope �eld of view. Despite of that, the real intersection point lies de�nitely not in the center of the image, which can be clearly seen on right part of Fig. 1. 99 Advances in Astronomy and Space Physics V. Ya. Choliy, V. P. Zhaborovskyy Satellite positions Navigation messages in RINEX format and �nal orbits in SP3 �les were used to determine satellite positions according to GPS [3] and GLONASS [4] interface control documents. For GPS the keplerian elements (a, e, i0, Ω0, ω0, M0, ∆n) their time derivatives ( dΩ dt , dω dt , di dt ) and per- turbation model (Cic, Cis, Crc, Crs, Cuc, Cus) were extracted for the moments, closest to the observations. Coordinates in orbital reference frame were then deduced according to the following algorithm: n = √ γM⊕ a3 + ∆n, M = M0 + n(t− te), E − e sinE = M → E, tan v = √ 1− e2 sinE cosE − e → v, u = ω + v, Ω = Ω0 + dΩ dt (t− te) + Ω⊕(t− t0), i = i0 + Cic cos (2u) + Cis sin (2u) + di dt (t− te), ω = ω0 + Cuc cos (2u) + Cus sin (2u), r = a(1− e cosE) + Crc cos (2u) + Crs sin (2u), (1) and the coordinates itself: r = ( a(1− e2) 1 + e cos v cosu, a(1− e2) 1 + e cos v sinu, 0 ) , (2) where γM⊕ is the geocentric gravitational constant, Ω⊕ is the Earth's rotation velocity, te is the moment of ephemeris data. The di�erence (t−te) never exceeds 2h for GPS and 30m for GLONASS. Then coordinates (2) are transformed to equatorial reference frame (in our case it is ICRF � International Celestial Reference Frame): rICRF = R(−Ω) · P(−i) · R(−ω)r, (3) where P and R are rotation matrices: P(α) = ( 1 0 0 0 cosα sinα 0 − sinα cosα ) , R(α) = ( cosα sinα 0 − sinα cosα 0 0 0 1 ) . (4) SP3 �nal orbits [5] contain satellite positions for every 15 min. They should be interpolated to �nd position on desired moment. In contrary to GPS, determination of GLONASS position implies numerical integration of satellites equations of motion:    dr dt = V, dV dt = γM⊕ · r r3 · ( −1 + 3C20a 2⊕ r2 ( k − 5 z r2 )) + j( + j¯, (5) where k = 3 for z and k = 1 for x and y. These equations account for perturbation from second zonal geopotential garmonics C20 and direct in�uence of the Sun (j¯) and the Moon (j(). One should select the data from RINEX �le for the closest possible moment and integrate to the moment of interest. There are no SP3 �les for GLONASS. De�ection angles Coordinates rs and r′ in two di�erent reference frames satisfy the Helmert transform [1]: rs = ( µ1 R −Q −R µ2 P Q −P µ3 ) r′ + a, (6) 100 Advances in Astronomy and Space Physics V. Ya. Choliy, V. P. Zhaborovskyy where P , Q and R are rotation angles around x, y and z correspondingly, µi are the scale factors, a is the center shift vector. Having coordinates of the same point in two reference frames one can solve (6) for rotation angles, scales and shift vector. Unfortunately, we cannot account GLONASS satellite coordinates in GPS dynamical reference frame and vice versa. That is why the third reference frame � optical one � was used. If we have transformation angles from optical frame to the �rst and the second ones: P1, Q1, R1 and P2, Q2, R2, they can be presented as ephemeris values Be with small corrections ∆B as Be + ∆B. Thus they satisfy the following relation [6]: ( P Q R ) = ( 0 cos Pe1 sinPe1 cosQe1 1 0 sinQe1 0 − sinPe1 cosPe1 cosQe1 )( ∆P1 −∆P2 ∆Q1 −∆Q2 ∆R1 −∆R2 ) . (7) Ephemeris values for rotation angles may by calculated from: tanP1 = tan i sinΩ; sinQ1 = sin i cosΩ; tan(R1 + ω) = tan Ω/ cos i. (8) Equations (7) can be modi�ed to trivial ones: P = ∆P2 −∆P2, Q = ∆Q1 −∆Q1, R = ∆R3 −∆R3 (9) in the case of geostationary satellites or when a satellite crosses the equator. Results and conclusions We used Astrometrica software [7] with UCAC2 astrometric catalogue [2] for processing the pictures. Three kinds of observations were used to deduce P, Q, R between GPS and GLONASS dynamical Reference frames. Typical result is present below: ( P Q R ) = ( 2.38± 1.88 1.56± 1.32 −0.90± 1.06 ) ; a = ( 0.070± 1.420 −0.703± 1.420 1.413± 1.128 ) , (10) angles in arcsec, shifts in km. Di�erences between two reference frames are above their errors, especially P , Q and z components of a. They are quite large and need further analysis. Acknowledgement Authors kindly acknowledge M. Andreev from Terskol observatory for his help in optical observations. References [1] Ho�man-Wellenhof B., Lichtenegger H., Collins J. Global Positioning System � Theory and Practice, McGraw Hill, NY (1995) [2] Zacharias N., Urban S. E., Zacharias M. I. et al. Astron. J., V. 127, pp. 3043-3059 (2004) [3] GPS Interface Control Document. Rev. D. ICD-GPS-200D, Navstar GPS Space Segment (2003) [4] GLONASS Interface Control Document. Rev. 5. 1. ICD-GLONASS-5.1, RosNII SI (2008) [5] http://www.ngs.noaa.gov/orbits/ [6] Duma D. P. Determination of mutual orientation of stellar catalogues, Naukova Dumka, Kyiv, (1968) [7] Raab H., http://www.astrometrica.at/ 101