: : : Уважаемая Valia!
: :
: : : Констатирую: в современной небесной классической механике используется значение гравитационной постоянной измеренное на Земле
: :
: : Тут вкралась неточность: в современной небесной классической механике используется гауссова гравитационная постоянная, которая отличается от рассматриваемой Вами гравитационной постоянной.
: :
: : Смотрите здесь:
: : http://www.astronet.ru/db/msg/1190817/node58.html
: _______
: В настоящее время в мировом научном сообществе принято, что достоверно, с погрешностью 0.15% измеренное среднее значение величины гравитационной постоянной G на Земле равно в системе единиц CGS
:
: G = 6.67259(85) *10 в минус 8 -ой степени [см3 /г с2].
:
: В указанной Вами ссылке приведено значение для G в системе единиц SI:
:
: G = 6.673 * 10 в минус 11 - ой степени [ м3 / кг с2 ],
:
: которое в пределах указанной мной погрешности соответствует G измеренному на Земле.
: Гаусс великий человек, но от использования его имени суть проблемы, состоящая в сравнительно низкой точности определения G любыми известными методами по сравнению с С не меняется.
Это же небесная механика, а у них все по-своему... для обеспечения максимальной точности!
В небесной механике, и уже очень давно, существует своя система уравнений, в которой для удобства и повышения точности объединены еще Гауссом две величины G и масса Солнца. Отдельно G и масса Солнца в небесной механике не рассматриваются, т.к. они выпадают в безразмерных отношениях.
гауссова гравитационная постоянная включает массу Солнца, т.к., например, массы планет находятся относительно массы Солнца, которая принимается равной 1 :-)
этим приемом и обеспечивается восхитительная точность в !0-11 для отношений в небесной механике...
TABLE I 1994 IAU File of Current Best Estimates
Constant Alphameric Value Units Ref Description
Defining Constants
k GAUSSK 0.01720209895 [au3/day2]1/2 Gaussian gravitational constant.
------------------------------------------------------------------------
Загляните в Астрономические постоянные, например, для DE405, и Вам многое станет понятным
Поищите вот этот документ или я вышлю его Вам, т.к. именно раздел Астрономические постоянные отобразился с ошибками:
Report of the IAU WGAS Sub-group on Numerical Standards
E. M. Standish, Chair JPL/Caltech
301-150; Pasadena, CA 91109; USA @
Abstract.
The Report of the Sub-Group on Numerical Standards of the IAU Working Group on Astronomical Standards (WGAS) is presented. The report is intended to incorporate the majority of the responses received from the e-mail recipients of the series of WGAS Circulars. The report proposes to retain the present (1976) IAU System of Astronomical Constants and also proposes to establish a IAU File of Current Best Estimates. Further, the report proposes the establishment of a Maintenance Committee, governed by a set of proposed by-laws, in order to oversee the maintenance of the new file.
1 Introduction
The present IAU System of Astronomical Constants provides a stable standard for the consistent reduction of observations. However, such a system is inadequate for current high-precision astronoѓmy. Thus, it is desirable to both retain the present system and to also provide a more current set of values. Furthermore, since improved techniques of measurement now require not only more accurate numerical constants, but also more sophisticated formulation, consideration must be given to coordiѓnating the presentation of the numerical constants with associated algorithms and formulations.
Therefore, it is proposed to
1. Retain the present "1976 IAU System of Astronomical Constants".
2. Establish an "IAU File of Current Best Estimates" whereby the accuracy of current astronomical data computations is made available to the astronomical community.
3. Establish a "Maintenance Committee" to oversee the maintenance of the File of Current Best Estimates.
4. Establish a set of By-Laws to govern the actions of the Maintenance Committee.
This paper presents an initial File of Current Best Estimates, an initial set of guidelines for the establishment of a Maintenance Committee to govern the file, and an initial set of By-Laws to govern the Maintenance Committee. The initial File of Current Best Estimates is discussed in the next section and the file itself is given in the Table I; the By-Laws and the establishment of the Maintenance Committee are given in Sections 3 and 4.
2 The 1994 IAU File of Current Best Estimates
Table I presents the 1994 IAU File of Current Best Estimates.
When the difference is significant, values are given for both the previously used TDB units and for the newly adopted SI units. The value of LQ comes directly from Wo/с2 For the conversion of ТА and СТА into SI units, the TDB values are multiplied by the factor (1 + LB)3); for GE and Gs, the TDB values are multiplied by the factor (1 + LB)-
The uncertainties, given in parentheses, are intended to be realistic values, as opposed to formal ones.
For cases where there are two or more valid sources for the same constant, each is given.
3 By-Laws Governing the IAU File of Current Best Estimates
This section presents an initial set of by-laws to govern the IAU File of Current Best Estimates. The contents and maintenance of the File are outlined first; the composition of the Maintenance Committee and amendments to the By-Laws are discussed afterward.
3.1 AUTHORITY
There is to be a Maintenance Committee whose purpose is to maintain the IAU File of Current Best Estimates. The Committee is to be governed by this present set of By-Laws.
3.2 CONTENTS OF THE FILE OF CURRENT BEST ESTIMATES
The IAU File of Current Best Estimates is to contain a list of selected astronomical parameters. For each parameter, the list is to include
1. an alphameric name of no more than 6 characters,
2. the current best estimate of its numerical value,
3. an estimate of its realistic uncertainty (standard deviation),
4. a description of the physical units in which the quantity is expressed,
5. a reference to the source of the value,
6. an identifying name or definition of the parameter.
3.3 SCOPE OF THE FILE
The File is to include any parameter which is contained in the IAU System of Astronomical Constants and for which there is a more accurately determined value. In addition, the File may contain values for other descriptive parameters of astronomical objects. Objects to be considered in the future include the planets, satellites, asteroids, comets, sun, and extra-solar-system objects; descriptive parameters of these objects may be masses, shapes, gravity fields, orientation parameters, etc. Consideration should also be given to ephemerides, catalogues, station locations, plate motions, etc.
When deciding which parameters are to be included, care is to be taken not to usurp the jurisdiction of other scientific groups or to create inconsistencies by providing alternate values of quantities which are given elsewhere.
3.4 SELECTION OF PARAMETER VALUES
The Maintenance Committee is to maintain quality control over the values to be included in the File. The Committee is to consider values of parameters provided by any legitimate source, not necessarily restricted to published values. The Committee may also decide to automatically adopt certain Files from other IAU Commissions or from other scientific sources. However, the Maintenance Committee is to be responsible for the integrity of the File; it must decide whether a parameter is appropriate for inclusion in the File and whether a suggested value is reliable. Furthermore, the Committee must decide whether a published value should be altered (for purposes of round-off, correction of errors, change of units, etc.). The Committee must decide which units are most appropriate for each parameter.
3.5 UPDATING THE FILE: FREQUENCY AND SCHEDULE
The IAU File of Current Best Estimates is to be updated only at the beginning of a calendar year and only if it is deemed, by the Maintenance Committee, that there is a significant reason for doing so.
In order for the value of a parameter to be changed or to be included in the File, the Maintenance Committee must receive, electronically or in writing, the proposed action on or before the first of September. The Maintenance Committee is to formally accept or reject any proposed addition or change on or before the first of December. The newly amended File is to be sent to the Distribution Centers by December 15; the Distribution Centers are to incorporate the updated File during the last half of December.
3.6 ARCHIVING
The name of each File is to include the calendar year during which the File was the active IAU File of Current Best Estimates. The active File and all previously active Files are to be immediately accesѓsible, electronically, from the designated Distribution Centers. All Files are also to be permanently archived on suitable electronic media, such as CDrom's, magnetic tapes, etc.
3.7 DISTRIBUTION
There is to be a central Distribution Center, chosen by the Maintenance Committee, which will, in turn, distribute the two files to a number of secondary distribution centers, located so as to provide comfortable access around the world. The files are to be made available in hard copy as well as via some suitable electronic medium such as anonymous FTP, electronic-mail, or electronic bulletin boards. The distribution process may be coordinated with the Sub-Group on Standard Procedures.
3.8 AMENDMENT OF THE BY-LAWS
Subsequent amendments to these By-Laws are to be presented to and voted upon by all members of the IAU Commissions represented in the enabling Joint Commission (IAU Commissions 4, 5, 8, 19, 24, and 31). Proposed amendments must be presented four weeks in advance of the voting; acceptance is by a two-thirds majority of all of the voting members.
3.9 COMPOSITION OF THE MAINTENANCE COMMITTEE
The composition of the Maintenance Committee is to reflect the range of disciplines represented by the sponsoring Joint Commission (IAU Commissions 4, 5, 8, 19, 24, 31). The composition should also display a wide national and geographic distribution.
The Committee is to include, but not be limited to, a Chair, a Vice Chair, and liaison memѓbers from the IERS standards committee, the IUGG standards committee, the IAU Cartographic Coordinates Working Group and each of the sponsoring IAU Commissions.
The members and officers of the Maintenance Committee are to assume their duties at the conѓclusion of each IAU General Assembly. The terms of Chair and Vice-Chair are three years each; the Vice- Chair normally assumes the role of Chair at the time of change. The term for a normal Committee member is six years; these should be staggered so that approximately half of the members are replaced at each time of change. The lengths of the terms of the liaison members may be left unspecified.
4 Initial Maintenance Committee for the IAU File of Current Best Estimates
The initial Maintenance Committee is to be appointed by the current Chair of the IAU Working Group on Astronomical Standards along with the other three leaders of the WGAS Sub-Groups. The selection process is to follow the guidelines set forth in Section 3.9 of the By-Laws. The acceptance of the initial Maintenance Committee is to require a majority vote of all members of IAU Commissions 4, 5, 8, 19, 24, and 31.
5 Conclusions
The mechanism of a two-tiered approach to supplying astronomical constants has been proposed. The presently used standard system of astronomical constants is to be retained and is to be accessible electronically. A second file is to be established which contains state-of-the-art values. Further, an archival system is proposed whereby any past set of values can be uniquely retrieved. Maintenance of the files is given by a set of by-laws.
Acknowledgements
The research in this paper was carried out by the Jet Propulsion Laboratory, California Institute of Technology, under a contract with the National Aeronautics and Space Administration.
References
Anderson,J.D., Colombo,G., Esposito,P.B., Lau,E.L. and Trager,G.B.: 1987, "The Mass, Gravity Field, and Ephemeris of Mercury", Icarus, 71, 337-349.
Sjogren.W.L., Trager.G.B. and Roldan.G.R.: 1990, "Venus: A Total Mass Estimate", Geophys. Res. Let., 17(10), 1485-1488.
JPL Planetary and Lunar Ephemeris DE245
Null,G.W.: 1969, "A Solution for the Mass and Dynamical Oblateness of Mars Using Mariner-IV Doppler Data", Bull. Am. Astr. Soc, 1(4), 356.
Campbell,J.K. and Synnott,S.P.: 1985, "Gravity Field of the Jovian System from Pioneer and Voyager Tracking Data", Astron. J., 90(2), 364-372.
Campbell,J.K. and Anderson,J.D.: 1989, "Gravity Field of the Saturnian System from Pioneer and Voyager Trackѓing Data", Astron. J., 97(5), 1485-1495.
Jacobson,R.A., Campbell,J.K., Taylor,A.H. and Synnott,S.P.: 1992, "The Masses of Uranus and its Major Satellites from Voyager Tracking Data and Earth-based Uranian Satellite Data", Astron J., 103(6), 2068-2078. Jacobson,R.A., Riedel,J.E. and Taylor,A.H.: 1991, "The Orbits of Triton and Nereid from Spacecraft and Earth-based Observations", Astron. Astrophys., 247, 565-575.
Tholen.D.J. and Buie.M.W.: 1988, "Circumstances for Pluto-Charon Mutual Events in 1989", Astron.J., 96(6), 1977-1982.
Fukushima,T.: 1994, "Time Ephemeris", to be published in Astron. Astrophys.
Bursa,M., Sima.Z.. Kostelecky,J.: 1992, "Determination of the Geopotential Scale Factor from Satellite Altimetry", Studia geoph. et geod., 36, 101-114.
Ries,J.C., Eanes,R.J., Shum.C.lv. and Watkins,M.M.: 1992, "Progress in the Determination of the Gravitational Coefficient of the Earth", GRL, 19(6), 529-531.
Williams,J.G., Newhall,X X and Dickey,J.O.: 1991,"Luni-Solar Precession: Determination from Lunar Laser Ranges", Astron. Astrophys., 241, L9-L12.
Miyamoto,M. & Soma,M.: 1993, "Is the Vorticity Vector of the Galaxy Perpendicular to the Galactic Plane? I. Precessional Correction and Equinoctial Motion Correction to the FK5 System", Astron J., 105, 691. Bursa,M.: 1992, "Parameters of Common Relevance of Astronomy, Geodesy and Geodynamics", Bull. Geod., 66(2), 193-197.
Moritz.H.: 1992, "Geodetic Reference System", Bull. Geod., 66(2), 187-192. Rapp: 1994, private communication via E. Groten.
TABLE I
1994 IAU File of Current Best Estimates
Constant
Alphameric
Value Units
Kef Description
Defining Constants
к GAUSSK
с CLIGHT
Primary Constants
Lc LSUBC
ТА TAUA
V PREC
e OBLIQ
Msun/Мл MRAT1
Msun/M-2 MRAT2
MSUH/MB MRATB
Msun/Mi MRAT4
Msun/Мъ MRAT5
Msun/Мв MRAT6
Msun/Мт MRAT7
Msun/Мц MRAT8
Msun/Mg MRAT9
M Moon Earth
MERAT
G GRAV
GE GME
aE RE
W0 WO
■h J2E
// FLATTG
w ROTE
0.01720209895 [an31 day2}1'2 299792458. m/s
SI : s TDB :
"/cty
1.4808268452(1) x 10 s 499.00478642(7) 499.00478384(7) 5028.83(4) 84381.412(5) 6023600.(250.) 408523.71(6) 328900.56(2) 3098708.(9.) 1047.3486(8) 3497.898(18) 22902.98(3) 19412.24(4) 1.35(7) x 108 0.012300034(3) 6.67259(30) x 10 s 398600.4415(8) x 109 398600.4356(8) x 109 6378136.55(1)
62636857.5(1.0) 62636856.26(1.0) 1082.6269(6) x 10~6
rad/s
1/298.257(1) 7292115. x 10~n
Gaussian gravitational constant Speed of light
[10] Mean of d(TCB)/d(TCG) - 1
[3] Astronomical unit
[13,14] General precession in longitude
[3] Obliquity of ecliptic ї J2000
[1] Mass Ratio: Sun/Mercury
[2] Mass Ratio: Sun/Venus
[3] Mass Ratio: Sun/(Earth+Moon)
[4] Mass Ratio: Sun/Mars system
[5] Mass Ratio: Sun/Jupiter system
[6] Mass Ratio: Sun/Saturn system
[7] Mass Ratio: Sun/Uranus system
[8] Mass Ratio: Sun/Neptune system
[9] Mass Ratio: Sun/Pluto system
[3] Mass Ratio: Moon/Earth
[15,16] Constant of Gravitation
[12] Geocentric gravitational constant
[17] Mean equatorial radius of Earth's
ellipsoid
[11] Potential of the geoid
[17]
[15,16] Zonal 2nd-degree geopotential
parameter
[15,16] Flattening factor for the Earth
[15,16] Mean angular velocity of Earth's
rotation
Derived Constants
LB LSUBB
LG LSUBG
СТА CTAUA
M Earth I MM oon EMRAT
Gs GMSUN
Msun/MEarth SERAT
1.550519747(3) x 10 s 6.9692903(1) x 10~10 149597871475.(30.) 149597870700.(30.) 81.30059(1) 1.327124 x 1020 1.32712442007 x 1020 332946.05(2)
SI : m TDB : m
SI : m3/s2 TDB : m3js2
Mean of d(TCB)/d(TT) - 1 Mean of d(TT)/d(TCG) - 1 Astronomical Unit
Mass Ratio: Earth/Moon Heliocentric gravitational constant
Mass Ratio: Sun/(Earth)
revised from m3/(gs2) in the original
отредактировано 19.03.2008 18:00 |
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