****************************************************************************** dorismail 16-Apr-2026 10:16:51 Message No 1482 ****************************************************************************** Author: Soudarin Laurent Subject: Extrapolated DORIS orbits for all the current missions Dear colleagues, To provide a complete dataset of orbits for NRT applications, a new approach has been set up. The delivery of the so-called "NRT orbits" (*) to IGN will be stopped at the end of May. They are replaced by extrapolated orbits derived from the SSALTO MOE orbits and created for all ten current missions: Cryosat-2, HY-2C, HY-2D, Jason-3, Saral, Swot, Sentinel-3a, Sentinel-3B, Sentinel-6A, Sentinel-6B These extrapolated orbits are now available at IGN and CDDIS in the directories doris/products/orbits/ssa//EXTRAPOLATED/ with the naming convention: ext30.bXXDDD.eYYEEE. d__.sp3.LLL.Z where is cs2, h2c, h2d, ja3, srl, swo, s3a, s3b, s6a, or s6b, "b" for begining and "e" for end, dates XXDDD and YYEEE in year (last two digits) and day of year. The format is sp3c but with precision extended with one digit in 'P' and 'V' blocks (f14.7 instead of f14.6 in standard sp3c). On day D, a file created a few hours after 0h is provided with the orbit from D 0h to D+5 0h. This means that the orbit is determined over the first hours and extrapolated over the remaining period, This also means that orbit and attitude maneuvers are not taken into account over the extrapolated period. With four days of extrapolation, routine processing can be ensured in the event of temporary delivery problems. Reminder: RINEX/DORIS data are available for the ten current missions with a latency of less than 3 hours, at the IGN data center. Their delivery to CDDIS is in preparation. If you have any questions, please do not hesitate to contact the Central Bureau. Best regards, Laurent Soudarin and Cécile Manfredi IDS Central Bureau (*) The "NRT orbits" are only available at IGN in doris/products/orbits/ssa//NRT/ for only seven missions (ja3, srl, swo, s3a, s3b, s6a, s6b). They are generated by Triode, a ground component that calculates the orbit from NRT DORIS data flow, as Diode does on board. Please do not reply directly to this message, but send comments and suggestions to IDS.central.bureau@cls.fr