============================================================================= INTERNATIONAL LASER RANGING SERVICE Shanghai Astromomical Observatory(SHAO) Analysis Strategy Summary ============================================================================= ANALYSIS CENTRE | Chinese Academy of Sciences | Shanghai Astromomical Observatory | Shanghai, China ----------------------------------------------------------------------------- CONTACT PERSONS | HU Xiaogong, | (hxg@shao.ac.cn, Phone:(86)21-64386191, FAX:64696291) | Wang Xiaoya | (wxy@shao.ac.cn, Phone:(86)21-64386191, FAX:64696291) ----------------------------------------------------------------------------- SOFTWARE USED | SHORD-II ----------------------------------------------------------------------------- ILRS PRODUCTS | weekly solutions for rang biases and time biases of | global SLR stations ----------------------------------------------------------------------------- PREPARATION DATE | effective since January 1, 2008 | version 01.01.2008 ============================================================================= ----------------------------------------------------------------------------- | MEASUREMENT MODELS | |---------------------------------------------------------------------------| | Satellites used | LAGEOS-1, LAGEOS-2, ETALON-1, ETALON-2 | |---------------------------------------------------------------------------| | Basic measurement| Satellite Laser Ranging (SLR): round-trip travel time | | |--------------------------------------------------------| | | speed of light : 299792458 m/s | | | wavelength : 532.0, 423.0, 847.0 & 694.3 nm| | | elevation angle cutoff : 10 degrees | | | weighting : 5-100 mm by station | | | range biases : est/d for selected stations | | | time biases : est/d for selected stations | | | tropospheric biases : not modeled/estimated | |---------------------------------------------------------------------------| | Data editing | 3.0 sigma editing | |---------------------------------------------------------------------------| | Troposphere | M-M zenith delay model | ||--------------------------------------------------------------------------| | Ionosphere | not modeled/estimated | |---------------------------------------------------------------------------| | Relativity | scale: LET (TT time scale) | | | effects: light time corrections | |---------------------------------------------------------------------------| | Satellite center | LAGEOS: 0.251 m | | of mass | ETALON: 0.580 m | |---------------------------------------------------------------------------| | Other | | |---------------------------------------------------------------------------| ----------------------------------------------------------------------------- | ORBIT MODELS | |---------------------------------------------------------------------------| | Geopotential | GGM01C (static terms through degree and order 30) | | | (C(2,0), C(2,1) and S(2,1) time dependent) | | |--------------------------------------------------------| | | Constants | | | AE = 6378.1363 km | | | 1/F = 298.2564 | | | GM = 398600.4415 km3/s2 | |---------------------------------------------------------------------------| | Third-body | planets: | | | Mercury, Venus, Earth Moon, Mars, Jupiter, Saturn, | | | Uranus, Neptune | | |--------------------------------------------------------| | | ephemeris: JPL DE403 | |---------------------------------------------------------------------------| | Solar radiation | IERS Conventions 2003 | | pressure | | | | direct radiation : applied | | | albedo radiation : applied | | | earth thermal radiation : not applied | | |--------------------------------------------------------| | | Earth shadow model includes: penumbra | | | | | |--------------------------------------------------------| | | reemitted radiation: not applied | |---------------------------------------------------------------------------| | satellite | modeled | | thermal thrust | LAGEOS: estimation of empirical (constant and | | | once-per-rev) along-track and (once-per-rev) | | | cross-track accelerations (1 set per 3-day | | | solution) | | | ETALON: estimation of empirical (constant and | | | once-per-rev) along-track and (once-per-rev) | | | cross-track accelerations (1 set per weekly | | | solution) | | | | |---------------------------------------------------------------------------| | Tidal forces | solid earth tides: IERS 2003 Conventions model | | |--------------------------------------------------------| | | Ocean tides: Ray GOT00.2 | |---------------------------------------------------------------------------| | Atmospheric | not modeled/estimated | | gravitational | | | attraction | | |---------------------------------------------------------------------------| | Dynamic | applied, IERS Conventions 2003 | | polar motion | | |---------------------------------------------------------------------------| | Relativity | point-mass accelerations, Lense-Thirring effect, | | | Coriolis force | |---------------------------------------------------------------------------| | Numerical | Cowell-Adamas 11th order predictor-corrector | | integration |--------------------------------------------------------| | | integration step: L1: 150 s, L2: 150 s, | | | arc length (orbits) : 3 days | | |--------------------------------------------------------| | |integration step: E1 & E2: 300 s | | |arc length (orbits): 7 days | ----------------------------------------------------------------------------- ----------------------------------------------------------------------------- | ESTIMATED PARAMETERS (APRIORI VALUES & SIGMAS) | |---------------------------------------------------------------------------| | Adjustment | weighted least-squares adjustment | |---------------------------------------------------------------------------| | Orbital | Initial position and velocity: | | parameters | estimated for each satellite (unconstrained) | | | Solar radiaton pressure: (unconstrained) | | | Empirical accelerations (unconstrained) | |---------------------------------------------------------------------------| | Stations | definition: SLR monument (eccentricities subtracted), | | | at mean epoch of each arc | | | a priori values: ITRF2000 | | | a priori standard deviation: 100000 m | |---------------------------------------------------------------------------| | Troposphere | not estimated | |---------------------------------------------------------------------------| | EOP | definition: x-pole, y-pole, UT1-UTC and LOD | | | epoch: at noon of each day | | | frequency: daily | | | a priori values: IERS 05 C04 | | | a priori standard deviation: 10000 masec, 1000 sec | |---------------------------------------------------------------------------| | Range biases | for some (non-core) stations | | | a priori value: 0 m | | | a priori standard deviation: 300 m | |---------------------------------------------------------------------------| ----------------------------------------------------------------------------- | REFERENCE FRAMES | |---------------------------------------------------------------------------| | Inertial | J2000.0 | |---------------------------------------------------------------------------| | Terrestrial | ITRF2000 (a priori station coordinates) | | | ITRF2000 (station velocities) | | | tidal corrections: IERS 2003 Conventions | | | ocean loading: GOT00.2 | | | atmospheric pressure loading: not modeled/estimated | | | geocenter motion: not modeled/estimated | | | geocenter tidal frequencies: not applied | | | pole tide: IERS 2003 Conventions | | | origin: C(1,0) = C(1,1) = S(1,1) = 0 | |---------------------------------------------------------------------------| | Interconnection | Precession: IERS Conventions 2003 | | |--------------------------------------------------------| | | Nutation: IAU 2000 | | |--------------------------------------------------------| | | Celestial pole: IERS 2003 Conventions | | |--------------------------------------------------------| | | Relationship between UT1 and GMST: IERS2003 Conventions| | |--------------------------------------------------------| | | Earth Orientation Parameters: estimated | | | (IERS 05 C04 a priori) | | |--------------------------------------------------------| | | Tidal variations in UT1 and PM: IERS 2003 Conventions | ----------------------------------------------------------------------------- ----------------------------------------------------------------------------- | OTHER INFORMATION | |---------------------------------------------------------------------------| | | | |---------------------------------------------------------------------------|