******************************************************************* WELCOME TO THE IfG FTP PRODUCT SERVER ftp://ftp.tugraz.at/outgoing/ITSG/satelliteOrbitProducts ******************************************************************* Institute of Geodesy - Satellite orbit products 10. August 2022 Graz University of Technology Institute of Geodesy Barbara Suesser-Rechberger barbara.suesser-rechberger@tugraz.at +43 316 873 6344 or: Torsten Mayer-Guerr mayer-guerr@tugraz.at +43 316 873 6359 Adress: Steyrergasse 30/III 8010 Graz, Austria Introduction: ------------- On this ftp server you can find following satellite orbit products produced at the Institute of Geodesy: - Kinematic orbit - Covariance - Reduced dynamic orbit - Attitude - Non-conservative forces - Neutral density Access is granted without any registration and free of charge. All provided products can be used for scientific research or any other application. Nevertheless, if you publish any results based on our products please add an acknowledgment. The satellite orbit products were processed with the GROOPS (Gravity Recovery Object Oriented Programming System) Software. GROOPS Open source version available at https://github.com/groops-devs/groops Description of the processing strategy can be found in: Suesser-Rechberger, B., Krauss, S., Strasser, S., & Mayer-Guerr, T. (2022). Improved precise kinematic LEO orbits based on the raw observation approach. Advances in Space Research, 69(10), 3559-3570. https://doi.org/10.1016/j.asr.2022.03.014 Krauss, S., Behzadpour, S., Temmer, M., & Lhotka, C. (2020). Exploring thermospheric variations triggered by severe geomagnetic storm on 26 August 2018 using GRACE Follow-On data. Journal of Geophysical Research: Space Physics, 125, e2019JA027731. https://doi.org/10.1029/2019JA027731 Data sampling: -------------- - Kinematic orbit and covariance data sampling corresponds to the measurement epochs and is not equidistant. POSITIONS and COVARIANCES ARE NOT INTERPOLATED TO INTEGER SECONDS NOR A CONSTANT SAMPLING!! - Reduced dynamic orbit, attitude and non-conservative forces data have a 10 s sampling. For easier interpolation both midnight epochs are included. - Neutral density data have an uniform sampling of 60 s for all satellites, for easier comparison. File naming convention: ------------------------ The filenames consist of three parts:satellite name, satellite orbit product and date. e.g.: CHAMP_kinematicOrbit_2007-01-01.txt.gz CHAMP_kinematicOrbitCovariance_2007-01-01.txt.gz CHAMP_reducedDynamicOrbit_2007-01-01.txt.gz CHAMP_attitude_2007-01-01.txt.gz CHAMP_nonConservativeForces_2007-01-01.txt.gz CHAMP_neutralDensity_ACC_2007-01-01.txt.gz File format description: ------------------------ All files are compressed. GROOPS format is used which is a simple ASCII format. - kinematicOrbit file: Contains the kinematic orbit position coordinates frame per epoch. Position coordinates are given in the celestial reference frame. column | content | unit ------------|-------------------------------------|--------------------------- 1 | epoch in Modified Julian Date (MJD) | day 2 | x-component of position | m 3 | y-component of position | m 4 | z-component of position | m ............................................................................ - kinematicOrbitCovariance file: Contains the elements of the 3x3 covariance matrix per epoch in the following way: xx yy zz xy xz yz. Elements are given in the celestial reference frame. column | content | unit ------------|-----------------|------ 1 | epoch in MJD | day 2 | xx-value | [m^2] 3 | yy-value | [m^2] 4 | zz-value | [m^2] 5 | xy-value | [m^2] 6 | xz-value | [m^2] 7 | yz-value | [m^2] ............................................................................ - Reduced dynamic orbit file: Contains the position coordinates and the velocity components of the reduced dynamic orbit per epoch. Position coordinates and velocities are given in the celestial reference frame. column | content | unit ------------|----------------------------|------ 1 | epoch in MJD | day 2 | x-component of position | m 3 | y-component of position | m 4 | z-component of position | m 5 | x-component of velocity | m/s 6 | y-component of velocity | m/s 7 | z-component of velocity | m/s ............................................................................ - attitude file: Contains the rotation from the satellite reference frame to the celestial reference frame in terms of quaternions per epoch. column | content | unit ------------|----------------------------|------ 1 | epoch in MJD | day 2 | scalar part | - 3 | qx-value | - 4 | qy-value | - 5 | qz-value | - ............................................................................ - nonConservativeForces file: Contains the accelerations due to non-conservative forces per epoch. Accelerations are given in the satellite reference frame. column | content | unit ------------|------------------------------------|------ 1 | epoch in MJD | day 2 | x-component of the acceleration | m/s^2 3 | y-component of the acceleration | m/s^2 4 | z-component of the acceleration | m/s^2 ............................................................................ - neutralDensity file: Contains the estimated neutral density per epoch. Abbreviation ACC in the file name indicates that the density estimate is based on on-board accelerometer measurements. The identifier KIN points out that the solution is based on kinematic orbit information. column | content | unit ------------|-------------------------------------|------ 1 | epoch in Modified Julian Date (MJD) | day 2 | neutral density | kg/m^3 ............................................................................