============================================================================= INTERNATIONAL LASER RANGING SERVICE Deutsches Geodaetisches Forschungsinstitut (DGFI) Analysis Strategy Summary ============================================================================= ANALYSIS CENTRE | Deutsches Geodaetisches Forschungsinstitut (DGFI) | | Munich, Germany | ----------------------------------------------------------------------------- CONTACT PERSONS | H. Mueller (mueller@dgfi.badw.de; tel +4989230311277) | ----------------------------------------------------------------------------- SOFTWARE USED | DOGS | ----------------------------------------------------------------------------- ILRS PRODUCTS | weekly solution for coordinates of global SLR stations | | and daily Earth Orientation Parameters (x,y-pole, | | LOD, UT1-UTC) (SINEX format) | ----------------------------------------------------------------------------- PREPARATION DATE | effective since June 1, 2003 | ============================================================================= ----------------------------------------------------------------------------- | 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 : as given on data record | | | elevation angle cutoff : 1 degree | | | weighting : 1.0 m to all data | | | range biases : modeled for stations of choice| | | time biases : for editing purposes only | | | tropospheric biases : not modeled/estimated | |---------------------------------------------------------------------------| | Data editing | 3.0 sigma editing | |---------------------------------------------------------------------------| | Troposphere | Mendes-Pavlis zenith delay model | | |--------------------------------------------------------| | | Mendes-Pavlis mapping function | |---------------------------------------------------------------------------| | Ionosphere | not modeled/estimated | |---------------------------------------------------------------------------| | Relativity | scale: LET | | | effects: light time corrections | |---------------------------------------------------------------------------| | Satellite center | LAGEOS: 0.251 m , 0.246 m for Herstmonceux | | of mass | ETALON: 0.558 m | |---------------------------------------------------------------------------| | Other | | |---------------------------------------------------------------------------| ----------------------------------------------------------------------------- | ORBIT MODELS | |---------------------------------------------------------------------------| | Geopotential | EGM96 (static terms through degree and order 70) | | | (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 DE405 | |---------------------------------------------------------------------------| | Solar radiation | IERS Conventions 1996 | | pressure | | | | direct radiation : applied (LAGEOS only) | | | albedo radiation : not applied | | | earth thermal radiation : not applied | | |--------------------------------------------------------| | | Earth shadow model includes: penumbra | | | lunar eclipses | | |--------------------------------------------------------| | | reemitted radiation: not applied | |---------------------------------------------------------------------------| | satellite | not modeled | | thermal thrust | estimation of empirical along-track constant (every | | | 3.5 days) and one once-per-rev per weekly solution and | | | empirical cross-track accelerations (once-per-rev) | | | 1 set per weekly solution) | |---------------------------------------------------------------------------| | Tidal forces | solid earth tides: Wahr model | | |--------------------------------------------------------| | | Ocean tides: Ray GOT99.2 | |---------------------------------------------------------------------------| | Atmospheric | not modeled/estimated | | gravitational | | | attraction | | |---------------------------------------------------------------------------| | Dynamic | applied | | polar motion | | |---------------------------------------------------------------------------| | Relativity | point-mass accelerations, Lense-Thirring effects, | | | coriolis force | |---------------------------------------------------------------------------| | Numerical | Cowell 7th order predictor-corrector | | integration |--------------------------------------------------------| | | integration step: 60 sec | | |--------------------------------------------------------| | | 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: 1 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 97 C04_05 | | | a priori standard deviation: 30 mas 2 msec | |---------------------------------------------------------------------------| | Range biases | for some (non-core) stationsi | | | a priori value: 0 m | | | a priori standard deviation: 1 m | |---------------------------------------------------------------------------| | Constraints | loose constraints | |---------------------------------------------------------------------------| ----------------------------------------------------------------------------- | REFERENCE FRAMES | |---------------------------------------------------------------------------| | Inertial | J2000.0 | |---------------------------------------------------------------------------| | Terrestrial | SLR2005 (a priori station coordinates) | | | SLR2005 (station velocities) | | | NUVEL-1A (2nd source for station velocities) (??????) | | | tidal uplift: Love model (h2=0.609, l2=0.0852) | | | ocean loading: Scherneck model, based on GOT99.2 | | | atmospheric pressure loading: not modeled/estimated | | | geocenter motion: not explicitly modeled/estimated | | | geocenter tidal frequencies: applied | | | pole tide: IERS Conventions (2003) | | | origin: C(1,0) = C(1,1) = S(1,1) = 0 | | | orientation: loose constraints | |---------------------------------------------------------------------------| | Interconnection | Precession: IAU 2000A (no corrections) | | |--------------------------------------------------------| | | Nutation: IAU 2000A (no corrections) | | |--------------------------------------------------------| | | Celestial pole offsets: none | | |--------------------------------------------------------| | | Relationship between UT1 and GMST: UT1-UTC estimated | | |--------------------------------------------------------| | | Earth Orientation Parameters: estimated | | | (IERS C04_05 a priori) | | |--------------------------------------------------------| | | Tidal variations in UT1 applied, xp not applied | ----------------------------------------------------------------------------- ----------------------------------------------------------------------------- | OTHER INFORMATION | |---------------------------------------------------------------------------| | | | |---------------------------------------------------------------------------|