============================================================================= INTERNATIONAL LASER RANGING SERVICE European Space Operations Centre (ESOC) European Space Agency (ESA) Analysis Strategy Summary ============================================================================= ANALYSIS CENTRE | European Space Agency (ESA) | European Space Operation Center (ESOC) | Navigation Support Office (OPS-GN) | Robert Bosch Strasse 5 | D-64293 Darmstadt | Fax: +49 6151 90 3129 -------------------------------------------------------------------------- CONTACT PERSONS | Dr. Werner Enderle | Werner.Enderle (at) esa.int.nospam | | Dr. Tim Springer | Tim.Springer (at) esa.int.nospam | +49 6151 90 2029 ----------------------------------------------------------------------------- SOFTWARE USED | Napeos 3.9.4 10/08/2015 ----------------------------------------------------------------------------- ILRS PRODUCTS | Daily and Weekly solutions (in SINEX format): | Coordinates of global SLR stations | Daily Earth Orientation Parameters | X-pole, Y-pole, and LOD | Range Biases for selected stations | Weekly satellite orbit files in SP3 format per satellite | ----------------------------------------------------------------------------- PREPARATION DATE | January 2009 ----------------------------------------------------------------------------- Modification dates| 2009-01-20: Creation | 2009-05-05: Update | 2014-05-16: Update for IERS2010 conventions | 2015-01-14: Update: constant cross-track acc. removed | 2016-03-16: Start official orbit submission | ....-..-..: Submission to ILRS | ----------------------------------------------------------------------------- Effective date | From 16/03/2016 for data analysis | ============================================================================= ============================================================================= 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 per ILRS NP/CDR format | elevation angle cutoff : 5 degree | weighting : 20.0 mm to 2-way range data of | CORE stations | range biases : estimated for selected stations | time biases : not modeled, not estimated | tropospheric biases : modeled, not estimated ----------------------------------------------------------------------------- Data editing | 4.0 WRMS editing ----------------------------------------------------------------------------- Troposphere | Mendes-Pavlis zenith delay model |---------------------------------------------------------- | Mendes-Pavlis mapping function ----------------------------------------------------------------------------- Ionosphere | not modeled/estimated ----------------------------------------------------------------------------- Relativity | scale: LET | effects: light time corrections ----------------------------------------------------------------------------- Satellite center | Nominal values: LAGEOS: 0.251 m ETALON: 0.576 m | But as far as available using station/satellite specific | values from the ILRS. ----------------------------------------------------------------------------- Tidal | Solid Earth tide: IERS 2010 (dehanttideinel.f routine) displacements |---------------------------------------------------------- | Permanent tide: zero-frequency contribution left in | tide model, NOT in site coordinates |---------------------------------------------------------- | Solid Earth pole tide: IERS 2010; mean pole modeled | by linear trend (Ch. 7, eqn 23a & 23b) |---------------------------------------------------------- | Oceanic pole tide: IERS 2010 updated model | No yet implemented! |---------------------------------------------------------- | Ocean tide loading: consistent with IERS 2003 (Ch. 7), | site-dependent amps & phases from Bos | & Scherneck website for FES2004 tide | model including CMC. | NEU site displacements computed | using hardisp.f from D. Agnew |---------------------------------------------------------- | Ocean tide geocenter: coeffs corrected for center of | mass motion of whole Earth |---------------------------------------------------------- | Atmosphere tides: corrections for S1 & S2 tidal | pressure loading not applied ----------------------------------------------------------------------------- Non-tidal | Atmospheric pressure: not applied loadings |---------------------------------------------------------- | Ocean bottom pressure: not applied |---------------------------------------------------------- | Surface hydrology: not applied |---------------------------------------------------------- | Other effects: none applied ----------------------------------------------------------------------------- Earth orientation| Ocean tidal: diurnal/semidiurnal variations in x,y, & variations | UT1 applied according to IERS 2010 (ortho_eop.f) |---------------------------------------------------------- | Atmosphere tidal: S1, S2, S3 tides not applied |---------------------------------------------------------- | High-frequency nutation: prograde diurnal polar motion | corrections (IERS 2003, Table 5.1) applied | using IERS routine PMsdnut.f and UT1LIB.f ------------------|---------------------------------------------------------- Other | ============================================================================= ============================================================================= ORBIT MODELS ----------------------------------------------------------------------------- Geopotential | EIGEN-GL05C | All terms through degree and order 20 | EIGEN-GLO5C has no time dependent terms | C21 & S21 computed according to IERS 2003 p.57 |---------------------------------------------------------- | GM=398600.4415 km**3/sec**2 (for TT/TDT time argument) |---------------------------------------------------------- | AE = 6378136.55 m Equatorial radius of the Earth | 1/f = 298.25769 Flattening factor of the Earth | | NOTE: | The above values are consistent with the "tide free" | system which we use. | | NOTE: | AE = 6378136.46 m for the EIGEN-GLO5C gravity field. | This value is used for the Gravity field expansion. ----------------------------------------------------------------------------- Third-body | Sun, Moon, Mercury, Venus, Mars, Jupiter, Saturn, | Uran, Neptune, and Pluto (i.e. All planets) |---------------------------------------------------------- | ephemeris: JPL DE403 ----------------------------------------------------------------------------- Solar radiation | IERS Conventions 2010 pressure | direct radiation : applied | albedo radiation : applied | Earth thermal radiation : applied |---------------------------------------------------------- | Earth shadow model includes: umbra, penumbra |---------------------------------------------------------- | Moon shadow: umbra & penumbra |---------------------------------------------------------- | Reemitted radiation: not applied ----------------------------------------------------------------------------- satellite | not modeled thermal thrust | LAGEOS: estimation of empirical parameters | Along-track: 1-set per week | constant and cosine and sine | Cross-track: 1-set per week | cosine and sine | ETALON: estimation of empirical parameters | Along-track: 1-set per week | Constant and cosine and sine ----------------------------------------------------------------------------- Tidal variations | Solid Earth tides: applied in geopotential | Procedure given in IERS Conventions 2003 Chapter 6.1 | Anelastic Earth model implemented. | Tables 6.1, 6.3a, 6.3b, and 6.3c fully implemented | Unchanged in IERS Convetions 2010 |---------------------------------------------------------- | Ocean tides: applied | Procedure given in IERS Conventions 2003 Chapter 6.4 | FES2004 spherical harmonics used. | Unchanged in IERS Convetions 2010 |---------------------------------------------------------- | Solid Earth pole tide: applied | Procedure given in IERS Conventions 2003 Chapter 6.2 | Unchanged in IERS Convetions 2010 |---------------------------------------------------------- | Oceanic pole tide: applied | Procedure given in IERS Conventions 2010 Chapter 6.x | New model of S. Desai for C21 and S21 terms only | Accounts for 90% of the effect ----------------------------------------------------------------------------- Atmospheric | not modeled/estimated gravitational | attraction | ----------------------------------------------------------------------------- Relativitic | dynamical correction: applied effects | IERS 2010, Ch. 10, eqn 1 |---------------------------------------------------------- | gravitational time delay: applied | IERS 2010, Ch. 11, eqn 17 ----------------------------------------------------------------------------- Numerical | Adams-Bashforth/Adams-Moulton 8th order prediction- integration | correction (multistep) method |---------------------------------------------------------- | integration step: 240 steps per revolution |---------------------------------------------------------- | starter procedure: Eight-order Runge Kutta (RKF) |---------------------------------------------------------- | arc length (orbits): 7 days ============================================================================= ============================================================================= REFERENCE FRAMES ----------------------------------------------------------------------------- Time argument | TDT (not TCG) is used. | UTC time as given by observation epochs, which is | offset by only a fixed constant (approx.) from TT/TDT ----------------------------------------------------------------------------- Inertial | J2000 | geocentric; mean equator and equinox of 2000 Jan 1.5 ----------------------------------------------------------------------------- Terrestrial | SLRF2008 (a priori station coordinates and velocities) ----------------------------------------------------------------------------- Interconnection | precession: IAU 2006A Precession-Nutation Model |---------------------------------------------------------- (EOP parameter | nutation: IAU 2006A Precession-Nutation Model estimation is | The daily dx and dy corrections from the below) | IERS Bulletin A are applied. |---------------------------------------------------------- | a priori EOPs: polar motion & UT1 interpolated from | IERS Bulletin A, updated daily, with the | restoration of subdaily EOP variations using | IERS models (see MODELS above) ============================================================================= ============================================================================= ESTIMATED PARAMETERS (APRIORI VALUES & SIGMAS) ----------------------------------------------------------------------------- Adjustment | Bayesian weighted least-squares adjustment ----------------------------------------------------------------------------- Orbital | Initial position and velocity: parameters | estimated for each satellite (unconstrained) | Solar radiaton pressure: | LAGEOS-1: CR kept fixed at 1.13 | LAGEOS-2: CR kept fixed at 1.13 | ETALON-1: CR kept fixed at 1.25 | ETALON-2: CR kept fixed at 1.28 | Empirical accelerations (unconstrained) ----------------------------------------------------------------------------- Stations | Definition: SLR monument (eccentricities subtracted), | at mean epoch of each arc | a priori values: SLRF2008 | a priori standard deviation: 1 meter ----------------------------------------------------------------------------- Troposphere | not estimated ----------------------------------------------------------------------------- EOP | Definition: x-, and y-pole, UT1-UTC and LOD | epoch: at noon of each day | frequency: daily | a priori values: IERS Bulletin A | a priori standard deviation: | 32 mas for x- and y-pole | 2 ms for LOD | 1e-6 ms for UT1UTC (but eliminated with 2ms constraint) ----------------------------------------------------------------------------- Range biases | Estimated for selected stations | a priori value: 0 m | a priori standard deviation: 1 m ----------------------------------------------------------------------------- Constraints | loose constraints ============================================================================= ============================================================================= OTHER INFORMATION ----------------------------------------------------------------------------- SINEX File | For the ILRS our SINEX files contain the covariances. | The covariance matrix reflects our loosly constraint | solution. ============================================================================= References : IERS Conventions 2003, D.D. McCarthy & G. Petit (editors), IERS Technical Note 32, Frankfurt am Main: Verlag des Bundesamts fuer Kartographie und Geodaesie, 2004. IERS Conventions 2010, G. Petit and Brian Lunzum (editors), IERS Technical Note 36, Frankfurt am Main: Verlag des Bundesamts fuer Kartographie und Geodaesie, 2010. The International Laser Ranging Service Pearlman, M.R., Degnan, J.J., and Bosworth, J.M.: Advances in Space Research, Vol. 30, No. 2, pp. 135-143, July 2002. EIGEN-GL05C A new global combined high-resolution GRACE-based gravity field model of the GFZ-GRGS cooperation, Ch. Foerste (1), F. Flechtner (1), R. Schmidt (1), R. Stubenvoll (1), M. Rothacher (1), J. Kusche (1), H. Neumayer (1), R. Biancale (2), J.-M. Lemoine (2), F. Barthelmes (1), S. Bruinsma (2), R. Koenig (1) and Ul. Meyer (1), Geophysical Research Abstracts, Vol. 10, EGU2008-A-03426, 2008 SRef-ID: 1607-7962/gra/EGU2008-A-03426 Ocean Loading Service by M.S. Bos and H.-G. Scherneck http://holt.oso.chalmers.se/~loading/