International Earth Rotation & Reference System Service (IERS) Site Survey (ISS) Program
The International Earth Rotation & Reference System Service (IERS) Site Survey (ISS) Program is responsible for conducting and reporting on local tie vector information for co-located geodetic technique instruments.
There are four distinct types of geodetic techniques;
- Very Long Baseline Interferometry (VLBI),
- Global Positioning System/Global Navigation Satellite System (GPS/GNSS)
- Doppler Orbitogrophy and Radiopositioning Integrated by Satellite (DORIS)
- Satellite Laser Ranging/Lunar Laser Ranging ( SLR/LLR).
At locations around the world where two or more of these geodetic techniques are in proximity to one another, they are considered to be co-located. The ISS program strives to conduct high precision local tie vector surveys at co-location sites considered priority sites by the International Earth Rotation & Reference System Service (IERS) for current and future International Terrestrial Reference Frame (ITRF) computations. To be truly beneficial in such computations, local tie vector information between techniques must be determined to a millimeter level of precision.
Additionally, the ISS program actively participates in the IERS Working Group on Co-location and Local Ties, which, among other things, develops standards and guidelines for conducting these type surveys.
