Work for nomination
The Latvian work for nomination of the Struve Geodetic Arc on the UNESCO World Heritage List has mainly been carried out by specialists from State agency “Latvian Geospatial Information Agency” and lecturers and students from Riga Technical University Civil engineering faculty Department of Geomatics.
Latvia is the only country in which both Friedrich Georg Wilhelm von Struve, as well Karl Tenner made measurements and built the station points. Wilhelm von Struve surveyed Northern part of Latvia till the point Jacobstatd, while Karl Tenner surveyed points in Southern part of Latvia – from Bristen to Pilkaln. There are 16 points entirely, from whom 11 are organized by Struve and 5 are organized by Tenner.
Two station points of Struve Geodetic Arc chain in Latvia - Sestu-Kalns (Ziestu) and Jacobstatd are designated as UNESCO World Heritage Sites.
The Sestu-Kalns geodetic point of Struve Meridian is located on the Ziestu hill (216,5 above sea level) in Sausneja Municipality, Madona Distric, close to the road Ērgļi – Koknese.
During establishing of the chain in 1824, the Sestu-Kalns point was properly marked and remain untouched until 1904, when Russian Military surveyors reconstructed it and included in new 1st Class triangulation chain and tied it up to prior line Sestukalns – Gaisakalns of the Struve Chain. Reconstructed point was marked with large granit stone carying inscribed year of reconstruction and the cross-typical surveying symbol.
The geodetic station point Jacobstatd, which also served as the place of astronomical observation, is located in Jekabpils town, Struve park. Total area of the park is 1,2 ha and it is tight by Struve street, both named to honour work of outstanding geodesist and astronomer Friedrich Georg Wilhelm von Struve.
The measuring of Jacobstatd point concluded the establishing the part of Struve chain- from Tarty to Jekabpils, these works were completed between 1822-1827. This point served as tieback to triangulation chains in Kurzeme and Lithuania, established by Karl Tenner. Through the establishing of the Jacobstatd point the Struve’s intention to include the survey triangulations of Vidzeme and Estonia in united Meridian was materialized. Jacobstatd point was measured and established in May—June 1826.
In nowadays Sestu-Kalns (Ziestu) and Jacobstatd points of Struve Geodetic Arc chain are used as 1st class triangulation points of horizontal geodetic basic network of Republic of Latvia.
In August 17-19 2011 specialists of Latvian Geospatial Information Agency and Riga Technical University organized an expedition to geodetic station point Bristen in Jaunjelgava District. The task of the expedition was to detect precise location of geodetic station point and to find the foundation of the Observatory. During 3 days of investigation work the Bristen geodetic station point and part of the observatory’s foundation were found. In fact only in August 31st the exact station point was completely revealed – it was located under a brick layer foud in 19th August and considered as the real geodetic point. The granit stone covered by bricks is carying inscribed year of foundation 1828 and the sign of cross.
State agency “Latvian Geospatial Information Agency” homepage http://www.lgia.gov.lv