IGS analysis centers provide satellite orbit solutions to the CDDIS using pre-determined schedules, e.g., sub-daily, daily, or weekly, depending upon the data product. The IGS analysis center coordinator retrieves these solutions and produces a combined product, which is then in turn archived at the CDDIS. These combination solutions are considered the official IGS products.
IGS orbit combination solutions are available in three forms: ultra-rapid, rapid, and final. The ultra-rapid product, useful for real-time and near real-time applications, at regular intervals four times per day; the ultra-rapid solution includes both observed and predicted satellite orbits. The rapid orbit combination is a daily solution available approximately 17 hours after the end of the previous UTC day. The final, and most consistent and highest quality IGS solutions, consists of daily orbit files, generated on a weekly basis approximately 13 days after the end of the solution week. All orbit solution files utilize the Extended Standard Product- 3 (SP3c) format.
All operational IGS GNSS products (i.e., orbits, station positions, EOP, clock solutions) are available in subdirectories by GPS week. Solution summary files are provided by the analysis centers in which they describe their analysis methods and strategies and list processing statistics. Descriptions of AC analysis procedures and models used are available from the IGS website.
In 2009 and 2013, the IGS initiated “reprocessing campaigns” (repro1 and repro2 respectively). The IGS analysis centers re-processed the GNSS data from the global network of IGS stations (from 1994 to 2007 for repro1, from 1994 through 2012/2013 for repro2) to produce a fully consistent set of products utilizing the most recent models and updated processing strategies. These reprocessed solutions are available within the weekly subdirectory structure as outlined below, in /repro1 and /repro2 subdirectories.
The starting directory for these files is:
ftp://cddis.gsfc.nasa.gov/gnss/products/ (GPS and GPS+GLONASS solutions)
ftp://cddis.gsfc.nasa.gov/glonass/products/ (GLONASS-only solutions)
Append the following directory and file names to the starting directory:
as described in the table below.
|emx||NRCan (GLONASS only)|
|iac||MCC (GLONASS only)|
|igl||IGS final solution combination (GLONASS only)|
|igr||IGS rapid solution combination|
|igs||IGS final solution combination|
|igu||IGS ultra-rapid solution combination|
|igv||IGS ultra-rapid solution combination (GLONASS only)|
|mcc||MCC (GLONASS only from SLR data)|
|ncl||University of Newcastle|
|eph||Satellite orbit solution|
|erp||Earth orientation parameter solution|
|sp3||Satellite orbit solution|
|sum||Orbit solution analysis summary|
|AAA||analysis center name/type of solution|
|D||day of week (0-6, 7 indicates weekly)|
|HH||2-digit hour (00, 06, 12, 18)|
|TYP||type of solution|
|.Z||UNIX compressed file|
Though many products are available, the products listed below have permanent DOIs:
|WWWW/igsWWWWd.erp.Z||Earth orientation parameter solution
|WWWW/igsWWWWd.sp3.Z||Satellite orbit solution
|WWWW/igsWWWWd.sum.Z||Orbit solution analysis summary
|WWWW/igrWWWWd.erp.Z||GNSS Rapid Combined Earth Rotation Parameter (ERP) Product
|WWWW/igrWWWWd.sp3.Z||GNSS Rapid Combined Orbit Solution Product
|WWWW/igrWWWWd.sum.Z||GNSS Rapid Combined Orbit Solution Summary Product
|WWWW/iguWWWWd_HH_cmp.sum.Z||GNSS Ultra-Rapid Orbit Solution Comparison Summary Product
|WWWW/iguWWWWd.erp.Z||GNSS Ultra-Rapid Combined Earth Rotation Parameter (ERP) Product
|WWWW/iguWWWWd.sp3.Z||GNSS Ultra-Rapid Combined Orbit Solution Product
|WWWW/iguWWWWd.sum.Z||GNSS Ultra-Rapid Combined Orbit Solution Summary Product