The Black Forest Observatory Data collection compiles digital data recorded at Black Forest Observatory (BFO) in Germany and provided through several international data centers. BFO aims to observe the entire geodynamic spectrum. It strives to ensure continuous, uninterrupted operation and is internationally recognized for high signal quality and sensitivity. Observed quantities cover three components of acceleration (including ground motion, gravity and tilt), strain, magnetic field, and others (see description of instruments below). The set of instruments and data recorders in operation provides a significant level of redundancy, which allows to distinguish natural phenomena from possible instrumental artefacts. The Black Forest Observatory (BFO) is a joint research facility of the Karlsruhe Institute of Technology (KIT) and the University of Stuttgart (Duffner et al., 2018; Gottschämmer et al. 2014). Since 1971 it is operated in cooperation of the geophysical and geodetic institutes of both universities (Zürn, 2014). BFO is staffed with two scientists and one technician. Main activities of the observatory fall into four categories, which are (1) observation and publication of a continuously recorded multi-parameter geodynamic data set, (2) research, (3) hosting of guest-experiments, and (4) teaching. The location of the observatory (48.3301 °N, 8.3296 °E) in the middle of the Black Forest was carefully selected at large distances to potential anthropogenic sources of noise. The instruments are deployed in a former silver mine in competent granite rock at a depth of up to 170 m below the surface and at up to 700 m distance from the entrance of the mine. This provides a thermally very stable environment. Two air-locks provide additional protection against air-pressure variations and ensure thermal stability. Because of these favorable conditions and the excellent high precision instruments operated at BFO the observatory is internationally well known as one of the most sensitive sites for long period observations, providing international standards for the scientific community, e.g. for recordings of Earth's free oscillations. The Black Forest Observatory operates broad-band seismometers (STS-1 and STS-2), gravimeters (superconducting gravimeter SG056, LaCoste Romberg earth-tide gravimeter ET-19), tiltmeters (Askania borehole tiltmeter, Horsfall fluid tiltmeter), an array of three invar-wire strainmeters, magnetometers (a scalar GSM-90 Overhauser magnetometer and a three component Rasmussen fluxgate magnetometers) and a permanent GPS-station. These are supplemented by regularly repeated magnetic base-line measurements and observations of absolute gravity as well as the recording of several environmental parameters (air-pressure, infrasound, humidity, wind speed, precipitation and temperature). Some of the latter are used to correct geodynamic recordings for remaining disturbances. The data are published in near-real-time through international data centers (IRIS DMC at Seattle, SZO at the BGR in Hannover, INTERMAGNET, GNSS Data Center at the BKG in Frankfurt, IGETS Database at GFZ Potsdam). Data are made available free of charge to scientific projects as well as to the general public with attribution as defined in the Creative Commons Attribution 4.0 International Licence (CC BY 4.0). An extended review of research at BFO is given by Zürn (2014) and Duffner et al. (2018, in German). Both provide references to published BFO research.

Black Forest Observatory is also known as 'Geowissenschaftliches Gemeinschaftsobservatorium des Karlsruher Instituts für Technologie und der Universität Stuttgart' and as 'Observatorium Schiltach' Data access • Records of most instruments are available through IRIS (http://ds.iris.edu) and FDSN web services (http://service.iris.edu/fdsnws/dataselect/docs/1/builder/) for channels of station BFO in network II (Scripps Institution of Oceanography, 1986, data since 1996) or station BFO in network BF (some data for dates before 1996). • Seismometer (STS-2) and infrasound data is available for station BFO in network GR (Federal Institute for Geosciences and Natural Resources, 1976). • Digital data of all essential instruments recorded with the HPMO long-period voltmeter data acquisition are available from summer 1990 to summer 2012. These data are not published, but will be made available upon request. • Data from superconducting gravimeter SG056 is available through the IGETS data center (Voigt et al., 2016, https://doi.org/10.2312/GFZ.b103-1608) under station name ‘Schiltach’ (https://isdc.gfz-potsdam.de/igets-data-base/). • Magnetic field recordings are provided for station BFO by INTERMAGNET (http://www.intermagnet.org/). • GNSS data for station BFO1 in network GREF is provided by the BKG GNSS Data Center (https://igs.bkg.bund.de/dataandproducts/browse).