============================================================================= INTERNATIONAL LASER RANGING SERVICE Federal Agency for Cartography and Geodesy (BKG) Analysis Strategy Summary ============================================================================= ANALYSIS CENTRE | Federal Agency for Cartography and Geodesy (BKG) | Department G1 | Frankfurt am Main, Germany ----------------------------------------------------------------------------- CONTACT PERSONS | M.Mareyen(maria.mareyen@bkg.bund.de); | phone:++49(69)6333287 | D.Thaller(daniela.thaller@bkg.bund.de); | phone:++49(69)6333273 ----------------------------------------------------------------------------- SOFTWARE USED | Bernese GNSS software ----------------------------------------------------------------------------- ILRS PRODUCTS | weekly solution for coordinates of SLR stations | and daily Earth Orientation Parameters | (x-,y-pole, LOD), SINEX and orbits (SP3C) ----------------------------------------------------------------------------- PREPARATION DATE | effective since May 1, 2014 | Bernese SW (AIUB) ============================================================================= ----------------------------------------------------------------------------- | MEASUREMENT MODELS | |---------------------------------------------------------------------------| | Satellites used | LAGEOS-1, LAGEOS-2, ETALON-1, ETALON-2 | |---------------------------------------------------------------------------| | Basic measurement| Satellite Laser Ranging (SLR): one-way-range | | |--------------------------------------------------------| | | speed of light : 299792458 m/s | | | wavelength : from QLNP/CRD observ. records | | | elevation angle cutoff : 3 deg. | | | sat.-dep. weighting : P_LAG/P_ETA=9.0 | | | station-dep. weighting : none | | | range biases : est/week,some non-core sites | | | time biases : not modeled/estimated | | | tropospheric biases : not modeled/estimated | |---------------------------------------------------------------------------| | Data editing | 2.5 sigma editing | |---------------------------------------------------------------------------| | Troposphere | Mendes-Pavlis zenith delay model | | |--------------------------------------------------------| | | Mendes-Pavlis mapping function | |---------------------------------------------------------------------------| | Ionosphere | not modeled/estimated | |---------------------------------------------------------------------------| | Relativity | scale: TT | | | light propagation corr.(Shapiro), | | | IERS2010 (Lense-Thirring,geodetic precession, PPN,GR) | |---------------------------------------------------------------------------| | Satellite center | Tables of CoM values from the 1980s to present | | of mass | Appleby,Otsubo:proceedings of the ILRS Workshop | | | held in Japan in November 2013. | |---------------------------------------------------------------------------| ----------------------------------------------------------------------------- | ORBIT MODELS | |---------------------------------------------------------------------------| | Geopotential | EIGEN_GL04C static terms through degree and order 70 | | | secular for C(2,0), C(3,0), C(4,0) | | |--------------------------------------------------------| | | Constants | | | AE = 6378.1363 km | | | 1/F = 298.25642 | | | GM = 398600.4415 km3/s2 (TT scale) | |---------------------------------------------------------------------------| | Third-body | bodies: Sun, Earth's Moon, Jupiter, Venus, Mars | | |--------------------------------------------------------| | | ephemeris: JPL's DE405 | |---------------------------------------------------------------------------| | Solar radiation | IERS Conventions 2010 | | pressure | direct radiation : applied | | | CR:1.13 for L1 and L2; CR:1.20 for E1 and E2 | | | albedo radiation : applied | | | earth thermal radiation : applied | | | Model from CERES mission (monthly grids) | | |--------------------------------------------------------| | | Earth shadow model includes: penumbra, lunar eclipses | | |--------------------------------------------------------| | | reemitted radiation: not applied | |---------------------------------------------------------------------------| | satellite | not modeled | | thermal thrust | 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 Conventions 2010 | | |--------------------------------------------------------| | | ocean tides: CSR4.0 | | |--------------------------------------------------------| | | atmospheric tides: Ray&Ponte model 2003 | | |--------------------------------------------------------| | | ocean pole tide: applied (Desai, IERS Conventions 2010)| |---------------------------------------------------------------------------| | Atmospheric | not modeled/estimated | | gravitational | | | attraction | | |---------------------------------------------------------------------------| | Dynamic | applied , IERS Conventions 2010 | | polar motion | | |---------------------------------------------------------------------------| | Relativity | point-mass accelerations, see measurement models | |---------------------------------------------------------------------------| | Numerical | Collocation method developed by G. Beutler | | integration | 12th order | | | step size 120 s | | |--------------------------------------------------------| | | arc length (orbit): 7 days | ----------------------------------------------------------------------------- ----------------------------------------------------------------------------- | ESTIMATED PARAMETERS (APRIORI VALUES & SIGMAS) | |---------------------------------------------------------------------------| | Adjustment | weighted least-squares adjustment | |---------------------------------------------------------------------------| | Orbital | per arc, per satellite: six osculating elements, | | parameters | constant + once-per-rev along-track accel, | | | once-per-rev cross-track accel | | | (all unconstrained) | | | Solar radiaton pressure: CR kept fixed at 1.13 | |---------------------------------------------------------------------------| | Stations | definition: SLR monument (eccentricities subtracted) | | | at mean epoch of each arc | | | a priori values: current SLRF20## | | | a priori standard deviation: 1 m for coordinates | |---------------------------------------------------------------------------| | Troposphere | not estimated | |---------------------------------------------------------------------------| | EOP | definition: x-pole, y-pole, LOD | | | epoch: at noon of each day | | | frequency: daily | | | a priori values: current IERS C04_0# | | | constraints: sigma of 1 meter equivalent to PM, LOD; | | | 4th UT constrained 0.0001 ms | |---------------------------------------------------------------------------| | Range biases | for some (non-core) stations | | | a priori value: according to ILRS settings | | | a priori standard deviation: 1 m | |---------------------------------------------------------------------------| | Constraints | loose constraints wrt apriori values: | | | 1 m equivalents for station coordinates, ERPs, | | | range biases | | | orbit parameter are unconstrained | |---------------------------------------------------------------------------| ----------------------------------------------------------------------------- | REFERENCE FRAMES | |---------------------------------------------------------------------------| | Inertial | J2000.0 | |---------------------------------------------------------------------------| | Terrestrial | current ITRF20## (a priori station coordinates) | | | current ITRF20## (a priori station velocities) | | | tidal uplift: Love model (h2=0.609, l2=0.0852) | | | ocean loading: Scherneck model, based on FES2004 + | | | subroutine HARDISP (IERS2010 conv.updates) | | | atmospheric pressure loading: not modeled/estimated | | | geocenter motion: not explicitly modeled/estimated | | | geocenter tidal frequencies: included in FES2004 model | | | pole tide: IERS Conventions 2010 | | | permanent tide corr.: applied in tide model, | | | not included in site coordinates | | | origin: C(1,0) = C(1,1) = S(1,1) = 0 and | | | realized by adjusted station coordinates| | | orientation: loose constraints to apriori ITRF20## | |---------------------------------------------------------------------------| | Interconnection | precession : IERS Conventions 2010 | | |--------------------------------------------------------| | | Nutation: IAU2000R06 | | |--------------------------------------------------------| | | Celestial pole offsets: IERS 2010 Conventions | | |--------------------------------------------------------| | | Relationship between UT1 and GMST: LOD estimated | | |--------------------------------------------------------| | | Earth Orientation Parameters: estimated | | | (IERS Bulletin A , a priori) | | |--------------------------------------------------------| | | Tidal variations in UT1 and PM: IERS 2010 Conventions | | |--------------------------------------------------------| | | Subdaily Pole Model: IERS 2010 Conventions | -----------------------------------------------------------------------------