Precise orbits products

ILRS Analysis and Combination Centers (AC & CC) provide a range of geodetic satellite orbital products for a select group of missions.

Precise satellite orbits for LAGEOS, LAGEOS-2 and Etalon-1 and -2 are generated weekly by all the ACs and based on these, a combined official product ILRS-A and ILRS-B is produced from both CCs. All these files are uploaded to the CDDIS and EDC archives using pre-determined schedules. The LAGEOS and Etalon orbits are computed using SLR data collected over one week; their reference frame is the Earth Centered-Earth Fixed (ECEF) realized by the latest SLR reference frame and the IERS Bulletin A EOP series (USNO).

By contrast, select LEO satellite orbits are computed through fits to SLR data collected over the previous three or four days and are provided daily as an output of the process used to generate orbital predictions in CPF format (a separate ILRS product). These orbits are for potential use by researchers outside of the direct ILRS community and at present they are provided by the UKRI/NERC/British Geological Survey Space Geodesy Facility (the NSGF AC).

All orbit solution files utilize the Extended Standard Product-3 (SP3c) format.

The starting directory for these files is:

Append the following directory and file names to the starting directory:

SATNAME/YYMMDD/ACNAME.orb.SATNAME.YYMMDD.vNN.sp3.gz

doi: 10.5067/SLR/SLR_ILRSORB_001.

as described in the table below.

Code Meaning
SATNAME etalon1, etalon2, lageos1, lageos2, ajisai, lares, larets, starlette, stella
YY 2-digit year
MM 2-digit month
DD 2-digit day
CENTERNAME
bkg
Bundesamt für Kartographie und Geodäesie (BKG) Germany
dgfi
Deutsches Geodätisches Forschungsinstitut (DGFI) Germany
esa
ESA/ESOC, Germany
gfz
Helmholtz Centre Potsdam German Research Centre for Geosciences (GFZ), Germany
ilrsa
ILRS primary combination solution - Italian Space Agency, Centro di Geodesia Spaziale "G. Colombo" (ASI/CGS), Italy
ilrsb
ILRS backup combination solution - Joint Center for Earth System Technology/Goddard Space Flight Center (JCET/GSFC) Greenbelt, Maryland, USA
asi
Italian Space Agency, Centro di Geodesia Spaziale "G. Colombo" (ASI/CGS), Italy
jcet
Joint Center for Earth System Technology/Goddard Space Flight Center (JCET/GSFC) Greenbelt, Maryland, USA
ngsf
NERC Space Geodesy Facility (NSGF) formely RGO Satellite Laser Ranging Group, United Kingdom
NN numeric version number
gz gzip compressed file