Subject: [SIR-Mail] No.1295: igs08_1854.atx: Update including Galileo, BeiDou, QZSS and IRNSS satellites From: Laura Sanchez This is a copy of [IGSMAIL-7126] igs08_1854.atx: Update including Galileo, BeiDou, QZSS and IRNSS satellites Dear IGS colleagues! The present release (called igs08_1854.atx) of the IGS antenna phase center model is the first to incorporate satellite antenna phase center corrections for the new GNSS (Galileo, BeiDou, QZSS, IRNSS). In order to facilitate a smooth transition, parallel files with and without the MGEX extension (called igs08_wwww.atx and igs08_wwww_woMGEX.atx, respectively) will be offered over a limited period of about 2-3 months. Previous igs08.atx users should verify that their software to read and/or convert the model is ready for the following new satellite antenna types: > +----------------------+-------------------------------------------------------+ > | Satellite Antennae | | > | IGS Codes-20 columns | Description | > | XXXXXXXXXXXXXXXXXXXX | | > +----------------------+-------------------------------------------------------+ > | BEIDOU-2G | BeiDou-2 GEO | > | BEIDOU-2I | BeiDou-2 IGSO | > | BEIDOU-2M | BeiDou-2 MEO | > | BEIDOU-3I | BeiDou-3 IGSO | > | GALILEO-0A | Galileo In-Orbit Validation Element A (GIOVE-A) | > | GALILEO-0B | Galileo In-Orbit Validation Element B (GIOVE-B) | > | GALILEO-1 | Galileo IOV : GSAT 0101-0104 | > | GALILEO-2 | Galileo FOC : GSAT 0201-0222 | > | IRNSS-1GEO | IRNSS-1 GEO | > | IRNSS-1IGSO | IRNSS-1 IGSO | > | QZSS | QZSS : SVN 01 | > +----------------------+-------------------------------------------------------+ defined in ftp://ftp.igs.org/pub/station/general/rcvr_ant.tab The corresponding frequency codes (e.g., ”E01”) can be found in the ANTEX format description available at ftp://ftp.igs.org/pub/station/general/antex14.txt For IRNSS (not yet contained in the format specification), the system identifier ”I” will be used in accordance with the upcoming RINEX 3.03 standard. The corresponding frequency codes are ”I05” (L5 band) and ”I09” (S band). As regards BeiDou, duplicate entries for ”C01” and ”C02” are provided for the B1 frequency band taking into account different signal specifications in RINEX 3.01/03 and RINEX 3.02. So far, the new ANTEX model provides only phase center offsets (PCOs) for the respective satellites, while phase center variations (PCVs) are set to dummy (zero) values over the required range of nadir/boresight angles. The PCO values are partly based on provider-supplied calibration values and partly conventional values as agreed upon for the IGS Multi-GNSS Experiment (MGEX): a) Galileo: conventional MGEX values for Galileo IOV/FOC satellites; ESA-supplied frequency-specific values for GIOVE-A/B (Zandbergen and Navarro, 2008: Specification of Galileo and GIOVE space segment properties relevant for satellite laser ranging, ESA-EUING-TN/10206); PRN numbers E51/E52 were adopted for GIOVE-A/B in accordance with previous MGEX practice and the majority of RINEX observation files b) BeiDou: conventional MGEX values; inofficial space vehicle numbers (SVNs) were assigned in the order of the launch dates c) QZSS: JAXA-supplied frequency-specific values; provided by Satoshi Kogure d) IRNSS: ISRO-supplied values; provided by Aiylam S. Ganeshan; inofficial SVNs were assigned in the order of the launch dates In accordance with recommendations of the IGS Workshop 2014 in Pasadena, the IGS has introduced an IGS-specific convention for the labeling of spacecraft axes, which is not necessarily identical to manufacturer-specifc coordinate systems used for other purposes (e.g., satellite laser ranging). Similar to GPS and GLONASS, the IGS-specific axis convention for Galileo, BeiDou, QZSS, and IRNSS has been chosen such as to allow a uniform modeling of the spacecraft attitude for all satellites applying a yaw-steering attitude control: * The +z-axis is the principal body axis closest to the antenna boresight direction (i.e., the direction of the maximum beam intensity). * The y-axis is parallel to the rotation axis of the solar panels. The positive y-direction is defined through the corresponding x-axis orientation. * The +x-direction is chosen such that the +x-panel is permanently sunlit during nominal yaw-steering, while the -x-panel remains dark at all times. Detailed definitions of the IGS-specific axis conventions are provided in Montenbruck O., Schmid R., Mercier F., Steigenberger P., Noll C., Fatkulin R., Kogure S., Ganeshan A.S. (2015) GNSS satellite geometry and attitude models. Adv Space Res, doi 10.1016/j.asr.2015.06.019 for all supported satellites and constellations along with a description of the relevant attitude modes. This Open Access publication is available at http://doi.org/10.1016/j.asr.2015.06.019. As further discussions and/or format modifications will be necessary, phase center information for the following frequencies/signals has not yet been considered for the igs08.atx model: a) GPS L5 (transmitted by SVN 49 and all Block IIF satellites) b) GLONASS G3 (transmitted by certain GLONASS-M and all GLONASS-K1 satellites) c) QZSS SAIF signal (transmitted by the auxiliary LS-ANT antenna) According to Hugo Fruehauf (Chief Engineer at Rockwell International in the 1970s), the helix array antenna of the initial five Block I satellites was centered on the front panel of the space vehicle. Therefore, the x-offset value for these satellites was corrected to zero. However, as all these Block I satellites were already decommissioned prior to 1993, IGS products are not affected by this update. The updated antenna correction model is available at ftp://ftp.igs.org/pub/station/general/igs08_1854.atx or ftp://ftp.igs.org/pub/station/general/igs08.atx Those who don´t cope with the MGEX extension can use the following model instead: ftp://ftp.igs.org/pub/station/general/igs08_1854_woMGEX.atx With best regards, Oliver Montenbruck and Ralf Schmid on behalf of the Multi-GNSS and the Antenna WG