The Iraqi Geospatial Reference System (IGRS) is a nationwide engineering initiative that combines a network of Global Positioning System (GPS) Continuously Operating Reference Stations (CORS) and a High Accuracy Reference Network (HARN) of permanently monumented survey control points.
The CORS Sites are located in the following six cities: IZBD ( Baghdad ), IZBA (Basrah), IZTL (Talil), IZBL (Balad), IZQW (Qayyarah), IZAD (Al Asad).
The HARN sites are concentrated near highways, cities, airports, seaports, and construction sites to support follow-on land surveys. Eventually, the HARN will consist of 3D control points spaced every 50-100km which will enhance the nation's spatial reference frame for precise navigation, mapping, and resource management.
175th Engineer Company (T)(AC), in cooperation with 42 Engineer Regiment (GEO) ( UK ) has created 64 of the proposed 300 HARN Sites, and 6 CORS sites. Technical assistance was added from the National Geodetic Survey (NGS) and National Geospatial-Intelligence Agency (NGA). The IGRS data is jointly managed by MNC-I C7 Geospatial and MND (SE) by the HQ Geographic Cell until a suitable Iraqi ministry can take control of the project.
Due to the threat levels and the fact that the reconstruction effort has been initiated in the UK Divisional AOR, MND (SE) it was decided that the IGRS project would start in MND (SE) and move north in line with other reconstruction projects.
Coordinates for each of the HARN stations were calculated using the NGS On-Line Positioning User Service (OPUS). OPUS allows users of both dual and single-frequency GPS units to process their data with respect to CORS stations within the International Terrestrial Reference Frame (ITRF). In this way, OPUS solutions may be derived from nearby CORS stations in Iraq , or by participating CORS stations in neighbouring countries. For more information on downloading and using CORS data visit the National Geodetic Survey at http://www.ngs.noaa.gov/CORS/ .
For more information on OPUS you may access the site at http://www.ngs.noaa.gov/OPUS/ . IGRS project leaders relied heavily on the precision, speed, accessibility offered by OPUS. For instance, when raw data files were submitted to OPUS, solutions were usually computed and returned within 10 minutes. The accuracy of OPUS derived solutions is typically at the 1-3 cm level in the horizontal component and 2-5 cm in the ellipsoid height component.
While OPUS solutions do not currently provide orthometric heights, these calculations were derived using the EGM96 Geoid Model calculator, which was downloaded from the National Geospatial Intelligence Agency (NGA). The OPUS values and associated errors are included in the Control Point Record (CPR); also, included is a printable table of coordinates, errors and MGRS values. Users may access the CPR from a link located at the bottom of each station. All values are true as at 25 August 2005.
Any enquiries should be directed to MNC-I C7 Geospatial or to HQ MND (SE) Geo Cell in the first instance.
Produced with help from Div Geo Cell, HQ MND(SE)