[IGSMAIL-8413] IGS experimental multi-GNSS ultra-rapid combinations [SEC=OFFICIAL]

Tue Jan 9 05:02:07 UTC 2024

Dear Colleagues,

I am pleased to announce that the IGS experimental multi-GNSS (GPS + Galileo + GLONASS) ultra-rapid orbit combinations are now available in the CDDIS (and soon other global data centres) starting from the products of the year 2023, day of year 358 (GPS week 2294). The products can be found in CDDIS as below:

1)     IGS combined multi-GNSS experimental orbits in SP3 format: https://cddis.nasa.gov/archive/gnss/products/<WWWW>/IGS0DEM_ULT<YYYY><DOY><HH>00_02D_05M_ORB.SP3.gz<https://cddis.nasa.gov/archive/gnss/products/%3CWWWW%3E/IGS0DEM_ULT%3CYYYY%3E%3CDOY%3E%3CHH%3E00_02D_05M_ORB.SP3.gz>
2)     Orbit combination summary files (new refreshed summary file format): https://cddis.nasa.gov/archive/gnss/products/<WWWW>/IGS0DEMULT_<YYYY><DOY><HH>00_02D_02D_SUM.SUM.gz<https://cddis.nasa.gov/archive/gnss/products/%3CWWWW%3E/IGS0DEMULT_%3CYYYY%3E%3CDOY%3E%3CHH%3E00_02D_02D_SUM.SUM.gz>
3)     Orbit combination summary files in machine-friendly JSON format: https://cddis.nasa.gov/archive/gnss/products/<WWWW>/IGS0DEMULT_<YYYY><DOY><HH>00_02D_02D_SUM.JSON.gz<https://cddis.nasa.gov/archive/gnss/products/%3CWWWW%3E/IGS0DEMULT_%3CYYYY%3E%3CDOY%3E%3CHH%3E00_02D_02D_SUM.JSON.gz>

where <WWWW> is GPS week, <YYYY> is the year, <DOY> day of year, and <HH> hour of the starting epoch of the file (start of the observed period in the ultra-rapid orbits). At this demonstration phase, these products will become available about 20 minutes after the ultra-rapid operational products (approximately at 03:20, 09:20, 15:20, 21:20 UTC).

It should be noted as the "DEM" Campaign/Project specification in the naming of the files suggests, these products are demonstration products and experimental only. Users are advised to continue using the operational products (IGS0OPS*) for their operational routines. The orbit combination algorithm of the demonstration products follows the methodology used for the IGS Repro3 campaign and described in a recently published paper Combination and SLR validation of IGS Repro3 orbits for ITRF2020<https://link.springer.com/article/10.1007/s00190-023-01777-3>.

Since these products include the three constellations GPS, Galileo and GLONASS, the IGS GLONASS ultra-rapid orbits (igv* products) will stop soon. Further announcements will be made as to the exact date the igv* products will stop giving ample time for the users to switch over to the new experimental multi-GNSS products. The DEM summary files contain the comparison statistics for the IGV products so that users can assess the level of difference between the new and old GLONASS orbits, as well as the differences to the operational GPS orbits.

Further developments and assessments of the multi-GNSS combinations are currently underway within the IGS ACC, IGS MGEX Pilot Project and the IGS multi-GNSS task force in order to progress further in achieving multi-GNSS combined products.

Kind Regards,
Salim Masoumi, Thomas Herring
IGS ACC Coordinator

Salim Masoumi PhD  |  GNSS Team Leader
GNSS Analysis Section  |  Positioning Australia Branch
Space Division

t +61 2 6249 9688    ga.gov.au<https://www.ga.gov.au/>

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