On 31 October 2020, anonymous ftp access will officially be discontinued at CDDIS. Beginning August 10, 2020, CDDIS will bandwidth limit ALL IPs using anonymous ftp to just 250KB/s transfer rates. CDDIS is STRONGLY recommending all users begin to transition to using alternate method of access to the CDDIS archive. Examples of alternate methods can be found at: https://cddis.nasa.gov/Data_and_Derived_Products/CDDIS_Archive_Access.html.

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Normal point data

Laser ranging normal points constitute the primary ILRS data product; they are generated following the conclusion of the laser pass and typically transmitted to the CDDIS within hours of the observation. SLR normal point data are transmitted in hourly and daily files where each file contains all data collected by the ILRS operations center in the previous hour or daily time period. Therefore, these daily files may contain data spanning several operating days. These daily and hourly files containing data from all satellites are available from the "allsat" subdirectory within the normal point archive area. Each day, the CDDIS updates monthly satellite-specific files containing all normal point data received to date for the month. The monthly files contain all normal point data for each satellite during the month.

As of 25-Apr-2017, the CDDIS has changed its directory structure for quarantined SLR data. The CDDIS recently implemented changes to our incoming SLR data processing and archiving procedures. These changes required that we now archive quarantined SLR data (both normal points and full-rate) in subdirectories by station number, rather than subdirectories by site name; these directories are located at:

Older data will be transitioned to this new structure in the near future. EDC has used this directory convention for its quarantined data files. Please contact the CDDIS manager if you have any questions or problems with the new CDDIS archive structure.

Daily and monthly normal point data are available from the CDDIS in subdirectories by satellite and year.

Files in current CRD format

Anonymous ftp service will be discontinued on October 31, 2020.

Append the following directory and file names to the starting directory:

allsat/YYYY/allsat_YYYYMMDDHHMI.npt (hourly file)
SATNAME/YYYY/SATNAME_YYYYMMDD.npt (daily file)
SATNAME/YYYY/SATNAME_YYYYMM.npt (monthly file)
SATNAME/YYYY/sum/SATNAME_YYYYMM.sum
(monthly sumary file)

as described in the table below.

Code Meaning
SATNAME Satellite name
YYYY4-digit year
MM2-digit month
DD 2-digit day
HH 2-digit hour
MI 2-digit minute

Files in former ILRS format

ftp://cddis.nasa.gov/slr/data/npt/
(daily and monthly files)

Anonymous ftp service will be discontinued on October 31, 2020.

Append the following directory and file names to the starting directory:

allsat/YYYY/allsat_YYMMDD.Z (hourly file)
SATNAME/YYYY/SATNAME.YYMMDD (daily file)
SATNAME/YYYY/SATNAME.YYMM (monthly file)
SATNAME/YYYY/sum/SATNAME_sum.YYMMDD
(monthly summary file)

as described in the table below.

Code Meaning
SATNAME Satellite name
YYYY4-digit year
YY 2-digit year
MM2-digit month
DD 2-digit day