International Laser Ranging Service (ILRS) Analysis and Combination Centers (AC & CC) provide a range of geodetic satellite orbital products for a select group of missions.
Precise satellite orbits for LAGEOS, LAGEOS-2, and Etalon-1 and -2 are generated weekly by all the ACs and based on these, a combined official product ILRS-A and ILRS-B is produced from both CCs. All these files are uploaded to NASA’s Crustal Dynamics Data Information System (CDDIS) and EDC archives using pre-determined schedules. The LAGEOS and Etalon orbits are computed using Satellite Laser Ranging (SLR) data collected over one week; their reference frame is the Earth Centered-Earth Fixed (ECEF) realized by the latest SLR reference frame and the IERS Bulletin A EOP series (USNO).
By contrast, select LEO satellite orbits are computed through fits to SLR data collected over the previous three or four days and are provided daily as an output of the process used to generate orbital predictions in CPF format (a separate ILRS product). These orbits are for potential use by researchers outside of the direct ILRS community and at present they are provided by the UKRI/NERC/British Geological Survey Space Geodesy Facility (the NSGF AC).
All orbit solution files utilize the Extended Standard Product-3 (SP3c) format.
The starting directory for these files is: https://cddis.nasa.gov/archive/slr/products/orbits/
Append the following directory and file names to the starting directory:
| File Naming Convention | SATNAME/YYMMDD/ACNAME.orb.SATNAME.YYMMDD.vNN.sp3.gz |
|---|
DOI: 10.5067/SLR/SLR_ILRSORB_001
as described in the table below:
| Code | Meaning | |
|---|---|---|
| SATNAME | etalon1, etalon2, lageos1, lageos2, ajisai, lares, larets, starlette, stella | |
| YY | 2-digit year | |
| MM | 2-digit month | |
| DD | 2-digit day | |
| ACNAME | Analysis Center name | |
| bkg | Bundesamt für Kartographie und Geodäesie (BKG), Germany | |
| dgfl | Deutsches Geodätisches Forschungsinstitut (DGFI), Germany | |
| esa | European Space Agency (ESA)/European Space Operations Centre (ESOC), Germany | |
| gfz | Helmholtz Centre Potsdam German Research Centre for Geosciences (GFZ), Germany | |
| ilrsa | ILRS primary combination solution - Italian Space Agency, Centro di Geodesia Spaziale "G. Colombo" (ASI/CGS), Italy | |
| ilrsb | ILRS backup combination solution - Joint Center for Earth System Technology/NASA Goddard Space Flight Center (JCET/Goddard) Greenbelt, Maryland, USA | |
| asi | ASI/CGS, Italy | |
| jcet | JCET/Goddard, Greenbelt, Maryland, USA | |
| ngsf | NERC Space Geodesy Facility (NSGF) formerly RGO Satellite Laser Ranging Group, United Kingdom | |
| NN | numeric version number | |
| gz | gzip compressed file | |