Orbit

Rapid Science Orbit (RSO) products for various Low Earth Orbiter (LEO) missions such as CHAMP, GRACE, GRACE-FO, TanDEM-X and TerraSAR-X in the CHORB format and the adjacent GPS constellation in sp3 format.

Each day a GPS constellation and a set of various LEO orbits is generated and uploaded to ISDC.
The RSOs come with a latency of two days.

Given example for the 27.06.2020 (year=2020, day of year=179).
For the 27.06.2020 the calculation date is -2 days, i.e. the 25.06.2020 (year=2020, day of year=177).

The GPS RSO constellations are 30 hour arcs starting at 9 pm the day before and ending at 3 am the day after.
   - Start=24.6.2020 21:00, End=26.6.2020 03:00 and will be saved to ISDC into the folder: "GPS/RSO/2020/177".

The LEO RSOs are generated based on these previous generated 30 hour GPS RSO constellations in two pieces for the actual day with arc lengths of 14 hours and overlaps of 2 hours.
   - The first starting at 10 am and ending at 12 pm
     -- Start = 24.6.2020 22:00 End = 25.6.2020 12:00
   - The second starting at 10 pm and ending at 12 am
     -- Start = 25.6.2020 10:00 End = 25.6.2020 24:00
These two arcs are then saved, f.i. for TanDEM-X (TDX), to ISDC into this folder: "TDX/RSO/2020/177" in the CHORB format.

- The GNSS folder syntax, accessible under:
   ftp://isdcftp.gfz-potsdam.de/gnss/<project>/RSO/<year>/<day of year>

  whereat <project> and <day of year> can be:
  <project>: GPS
  <day of year>: corresponds to the middle day of year of the arc

- The LEO folder syntax, accessible under:
   ftp://isdcftp.gfz-potsdam.de/<project>/ORBIT/<satellite_name>/RSO/<year>/<day of year>

  whereat <satellite_name> and <project> can be:
  <project>
          tsxtdx
          <satellite_name>
                       TDX: TanDEM-X
                       TSX: TerraSAR-X

  <project>
         grace-fo  
         <satellite_name> 
                      GFO: GRACE-FO

The exact time covered by the arc is defined in the files as well as in the filename.

F.i. GPS RSO constellation:
  <iCH/CH>-OG-3-RSO+<Reference system>-GPS_<start of the arc "yyyy_doy_hh">.dat
  CH-OG-3-RSO+CTS-GPS_2020_189_21.dat
  iCH-OG-3-RSO+TDS-GPS_2020_189_21.dat

F.i. TanDEM-X RSO:
  <satellite name>-ORB-3-RSO+<Reference system>-RSG_<start of the arc "yyyy_doy_hh_min"> <end  of the arc "yyyy_doy_hh_min">.dat
  TDX-ORB-3-RSO+CTS-RSG_2020_176_22_00_2020_177_12_00.dat
  TDX-ORB-3-RSO+TDS-RSG_2020_176_22_00_2020_177_12_00.dat 

The Accuracy of the:
- GPS RSO constellation sizes at the 3cm level in 3D RMS comparison to igs orbits
- LEO RSOs sizes at the cm level in 3D RMS comparison to f.i. a combined solution

The used software is GFZ “Earth Parameter and Orbit System” Software EPOS, additional information can be found under:
www.gfz-potsdam.de/en/section/global-geomonitoring-and-gravity-field/topics/earth-system-parameters-and-orbit-dynamics/earth-parameter-and-orbit-system-software-epos/

Additional information regarding RSO and NRT processing can be found under:
www.gfz-potsdam.de/en/section/global-geomonitoring-and-gravity-field/topics/earth-system-parameters-and-orbit-dynamics/operational-rso-and-nrt-orbit-determination/

Cite GFZ RSO products:

If you are using GFZ RSO products, we request that you include the corresponding DOI for citation:

xx.xxxx/GFZ_ORBIT.RSO-ORB-3