****************************************************************************** dorismail 07-Dec-2017 16:11:19 Message No 1092 ****************************************************************************** Author: Couhert Alexandre Subject: HY-2A POD instrument location updates Dear Colleagues, Following updated information on the coordinates of HY-2A POD instruments (DORIS, SLR, GPS) from the National Satellite Ocean Application Service (NSOAS), the MOE (DORIS-only) and POE (DORIS+GPS) precise orbits computed at CNES were updated today with the new phase center locations. The updated orbit solutions start with the MOE related to the day 2017-12-06 and the next POE orbit arc #320. The only difference for DORIS is a +2 cm offset on the instrument phase center positions for the Z satellite body axis (opposite to the radial direction). This correction should improve HY-2A-based scale factor and vertical station determinations of the DORIS network. The document 'DORIS satellites models implemented in POE processing', available at ftp://ftp.ids-doris.org/pub/ids/satellites/DORISSatelliteModel= s.pdf was updated accordingly, with a reference to the original HY-2A document from which the updates were provided (soon available). The main difference for the spherical center point (reference point) of the LRA is a -1 cm offset in the Z satellite direction. The updates for the phase center coordinates of the GPS receiver are marginal. NSOAS was notified of the need to also update the LRA reference point locations of HY-2A provided on the ILRS web site https://ilrs.cddis.eosdis.nasa.gov/docs/HY2_retroreflector.pdf. Best regards, Alexandre Couhert Centre National d'Etudes Spatiales Toulouse, France