Satellite laser ranging data are available through several methods. SLR data since 1976 are available online.
Access the SLR data using one of the following methods:
- via https at URL https://cddis.nasa.gov/archive/slr/data/
- via ftp-ssl using the command line and ftps://gdc.cddis.eosdis.nasa.gov
How are SLR data stored?
SLR data are available in subdirectories by data type, satellite, and year. The data type supported by the ILRS is on-site normal points, found in directories at URL https://cddis.nasa.gov/archive/slr/data/npt_crd.
What are the data types in the SLR subdirectories?
The primary data product for SLR is the on-site normal point data format. These data can be found a URL ftps://gdc.cddis.eosdis.nasa.gov/slr/data/npt in subdirectories by satellite and year. SLR full-rate data are available from 1976 through the present; however, since 1994, only a small subset of the global network are providing full-rate data. The full-rate data can be accessed at URL ftps://gdc.cddis.gsfc.nasa.gov/slr/data/fr_crd.
How can I access hourly SLR data files?
Hourly SLR data files are available through encrypted ftp at URL ftps://gdc.cddis.gsfc.nasa.gov/slr/data/npt/allsat/ in subdirectories by four-digit year. The filenames are of the form new_qlyymmdd#.allsat where yymmdd is the date and # is the hour of the day (a-x). Each file contains all the data received at the ILRS operations center within the last sixty minute period. Therefore, the hourly file could contain several hours worth of data. Hourly SLR data are available for the last five days. These data are removed after that time since the next day's daily files also contain these data.
Where can I find out more about SLR and LLR?
An overview of the SLR technique has been written by NASA. The home page of the International Laser Ranging Service (ILRS) is also an excellent source of information about SLR and LLR.
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