The International Geodynamics and Earth Tide Service (IGETS) was established in 2015 by the International Association of Geodesy (IAG). IGETS continues the activities of the Global Geodynamics Project (GGP, 1997-2015) to provide support to geodetic and geophysical research activities using superconducting gravimeter (SG) data within the context of an international network.
The gravimetric reference station Bad Homburg (Germany) is operated by the Federal Agency for Cartography and Geodesy (BKG) and was established in 1979. Continuous temporal gravity and atmospheric pressure time series from the different SGs is made available to the IGETS data base hosted by ISDC (Information System and Data Center) at GFZ.
The district town Bad Homburg is situated about 25 km north-east of Frankfurt/Main (longitude: 8.61 E, latitude: 50.23 N, height above MSL: 188 m) on the southern slope of the Taunus mountains. The gravity station is located inside a cellar of the Landgraves' Castle and is characterized by low environmental noise. Inside the vault a separated housing with insulated walls enables controlled environment. All rooms are thermally stabilized by an air-conditioning system. The station provides 5 separate piers of concrete (2 for SG, 3 for AG) which are grounded on bedrock (approx. 1.8 m deep, on greenschist) and are decoupled from the wooden floor.
Since 1981, an almost uninterrupted time series of gravity and barometric pressure variations was acquired with different SGs. In 1993, a series of repeated measurements with different absolute gravimeters (AG) was started.
From December 1999 to April 2007 the dual sphere SG CD030 was operated and since February 2007 OSG044 is recording. These data are available at the IGETS database.
The first SG installed at the station was TT40 (1981/04-1989/06, later at Richmond/Florida, USA) and TT60 (1985/06-1988/11, later at Wettzell/Germany). Several shorter test registrations were performed with SG103 (1998/12-1999/04), as well as SG030 (2008/02-2010/06) and SG029 (2011/03-2012/04) after upgrades.
In November 2003 and May 2004 two ground water wells within a distance of 200 m were constructed to support the monitoring of local water storage changes.
Due to the excellent stability of the station and the ability of facilities to inter-compare absolute and superconducting gravimeters, the station Bad Homburg was developed as a reference site for the national German gravity reference system.
In Addition, data from the superconducting gravimeter iGrav006 operated by GFZ Potsdam from March 2015 until March 2017 are available (Güntner et al., 2017, http://doi.org/10.5880/igets.we.gfz.l1.001).