NASA’s Crustal Dynamics Data Information System (CDDIS) archive of laser ranging products consists of solutions derived by analysis centers in support of the International Laser Ranging Service (ILRS). Products derived from these Satellite Laser Ranging (SLR) observations include precise satellite ephemerides, station positions and velocities of sites in the ILRS network, and Earth orientation parameters (EOPs) including polar motion and rates and length-of-day. ILRS analysis centers deliver the station position/EOP product to the ILRS data centers, including the CDDIS. The ILRS combination centers retrieve these solutions and produce the combined ILRS A and B solutions (generated by the primary and backup ILRS combination centers, respectively) which are in turn archived in CDDIS.
Prior to 2012, ILRS analysis centers generated the products on a weekly basis; today, these products are generated daily. Station positions and EOP date from 1976 through the present. SLR products are available from CDDIS in subdirectories by year and date.
Reference Frames
Product Formats
- Software INdependent EXchange (SINEX) format
The starting directory for these files is: https://cddis.nasa.gov/archive/slr/products/pos+eop/.
Append the following directory and file names to the starting directory:
| File Naming Convention | YYYY/YYMMDD/ACNAME.pos+eop.YYMMDD.v###.TYP.gz |
|---|
as described in the table below:
| Code | Meaning |
|---|---|
| YYYY | 4-digit year |
| YY | 2-digit year |
| MM | 2-digit month |
| DD | 2-digit day |
| ACNAME | Analysis Center Name |
| ### | version of solution |
| TYP | type of solution (SNX or SUM) |
| gz | Compressed file |