The HEllenic POsitioning System (HEPOS) is an RTK network consisting of 98 reference
stations that cover the entire area of Greece. HEPOS was established in 2007 by KTIMATOLOGIO
S.A. (Hellenic Cadastre). At the first stage, the system was solely used by the contractors of
KTIMATOLOGIO S.A. for the production of coordinates in HTRS07 (Hellenic Terrestrial
Reference System 2007), which is the geodetic reference system of HEPOS and a realization of
ETRS89 in Greece. After the issue of an official coordinate transformation model, connecting
HTRS07 to the national system GGRS87 (Greek Geodetic Reference System 1987, also known as
HGRS87 or EGSA87), KTIMATOLOGIO S.A. made HEPOS services available to the broad
The first part of this report describes the usage of HEPOS during the first year of operation, i.e.
from 5/2009 to 5/2010. Statistical data about the increase of users, the usage of the different
services and the spatial distribution of the requests are given.
The second part of the report deals with the EUREF GR 2007 campaign, i.e. the computation of
the HEPOS network in ETRS89 using EPN stations. The results of this campaign have been
recently validated by the Technical Working Group (TWG) of EUREF.
The last part of the report describes the computation of a geometric geoid model to be used
with HEPOS. This model is currently under development by KTIMATOLOGIO S.A.
Hellenic Positioning System
Technological Educational Institute of Athens