GFZ acts as a global analysis center of the International GNSS Service (IGS) and provides ultra-rapid (last 24h), rapid (last day), and final (last week) solutions for GPS and GLONASS. The ultra-rapid solution series is published eight times per day with a delay of around three hours.

Based on a network of around 100 GNSS stations of the tracking network of the International GNSS Service, the GFZ analysis center generates sub-daily solutions using the latest development version of the EPOS.P8 Software. The solution series contains daily files ( refers to the year and day of year of the first epoch contained in the files):

• satellite orbits (GFZ0OPSULT__02D_15M_ORB.SP3.gz, data format: sp3: ftp://igs.org/pub/data/format/sp3c.txt),

• Earth rotation parameters (GFZ0OPSULT__02D_01D_ERP.ERP.gz, data format: erp: https://lists.igs.org/pipermail/igsmail/1998/003315.html),

• summary file containing the detailed processing results (GFZ0OPSULT__01D_01D_DSC.SUM).

The file naming follows the IGS Long Product Filename (http://acc.igs.org/repro3/Long_Product_Filenames_v1.0.pdf). All files are .gz compressed. The processing is described in detail in our Analysis Center Notes (ftp://ftp.igs.org/pub/center/analysis/gfz.acn) and follows the current geodetic conventions (https://www.iers.org/IERS/EN/Publications/TechnicalNotes/tn36.htm).