Normal Point (NP) Availability

NP data, in the ILRS NP format, is available daily via either anonymous ftp or the web from the global data centers, CDDIS and EDC. Data is available from CSR as backup. Below is a table of these NP Data Centers along with accessibility information (i.e., node names, URLs, directory structure, filenaming conventions, and points of contact) followed by some examples of filename conventions.

The user needs to be aware of the different philosophies of how the daily NP files are managed by the data centers. The CDDIS and CSR daily files contain all data received within the last 24 hour period. Typically, these CDDIS and CSR daily files contain data from the previous one to two days or possibly even older data. However; the EDC daily files only contain data taken on that day. Therefore, the EDC daily files are updated often to capture subsequent incoming data for that day.

Category	CDDIS	EDC	CSR
Node Name	cddis.gsfc.nasa.gov	dgfi.badw-muenchen.de	csr.utexas.edu
URL	ftp://cddis.gsfc.nasa.gov/	ftp://ftp.dgfi.badw-muenchen.de/	ftp://ftp.csr.utexas.edu/
Root	pub/slr/npt/	pub/laser/qldata	pub/slr/slrql/
Directory Tree	satellite_name/yyyy/	satellite_name/sat_yyyy/	non applicable
Filename (Daily) Filename (Monthly)	satname.yymmdd satname.yymm	sat_yymm.dd sat_yymm.Z	all_qlyymmdd.all non applicable
Availability	since January 1988 (see note#1)	since December 1993	since 3 January 2000
Contact	Carey Noll Carey.Noll@nasa.gov	Wolfgang Seemueller seemueller@dgfi.badw-muenchen.de	John Ries ries@csr.utexas.edu

Notes: Since 1995, normal points are considered the primarly ILRS data product. All normal point data available from the CDDIS can be found in satellite and yearly subdirectories under ftp://cddis.gsfc.nasa.gov/pub/slr/data/npt/. Normal point data available from the CDDIS from 1988 through mid-1992 were generated from full-rate data; not all full-rate data yielded normal points. These filenames have the format satellite_V.YYMM.Z, where V is the SLR full-rate version and YYMM are the year and month. Normal point data available from mid-1992 through 1994 are in the form of both on-site normal points and sampled data (filename format satellite.YYMM.Z) and normal points generated from full-rate data (filename format satellite_V.YYMM.Z). All normal points since 1995 are in the form of on-site normal points only.

Directory and filename examples:

The CDDIS 01 January 2005 LAGEOS-1 daily full filename including directory is:

ftp://cddis.gsfc.nasa.gov/pub/slr/data/npt/lageos1/2005/lageos1.050101

The CDDIS January 1998 TOPEX monthly full filename of on-site normal ponits including directory is:

ftp://cddis.gsfc.nasa.gov/pub/slr/data/npt/topex/1998/topex.9801

The CDDIS January 1993 TOPEX monthly full filename of normal points generated from full-rate data including directory is:

ftp://cddis.gsfc.nasa.gov/pub/slr/data/npt/topex/1993/topex_b.9301

The EDC 14 February 2000 LAGEOS-1 daily full filename including directory is:

ftp://ftp.dgfi.badw-muenchen.de/pub/laser/qldata/lageos1/la1_0002.14

The EDC January 1998 TOPEX monthly full filename including directory is:

ftp://ftp.dgfi.badw-muenchen.de/pub/laser/qldata/topex/top_1998/top_9801.Z

Responsible Government Official: Carey Noll
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