From Deutsche Seewarte Hamburg to GeoForschungsZentrum ... · From Deutsche Seewarte Hamburg to GeoForschungsZentrum Potsdam – Wingst Geomagnetic Observatory during six decades

From Deutsche Seewarte Hamburg toGeoForschungsZentrum Potsdam – WingstGeomagnetic Observatory during six decades

G. SchulzErdmagnetisches Observatorium Winst, Am Olymp13, D-21789 Wingst

A b s t r a c t: At the beginning of the year 2000, the operation of Wingst Observatory wastransferred to GeoForschungsZentrum Potsdam. This is a good occasion for a brief retrospectivelook at the establishment of the observatory in 1938 and a few remarks on the development of itsinstrumentation. Special attention is given to the people who set the course at the very beginningas well as to those who influenced the observatory’s later development.

Keywords: observatories, history, instrumentation

1. History

Looking back at the late thirties, there existed two institutions in Germanywhich played a leading role in the establishment of Wingst observatory:

- the Marineobservatorium, Wihelmshaven, and - the Deutsche Seewarte (German Naval Observatory), Hamburg.

The Marineobservatorium had carried out geomagnetic observations forseveral decades at that time, starting in 1878 with two-hourly readings. No datarecords had been kept between 1919 and 1930, and the measurements weredefinitively stopped 1936 (three years after the Second International Polar Year1932/33) due to growing disturbances caused by electric streetcars and theexpansion of the docks of the city of Wilhelmshaven.

As a result, the entire geomagnetic department was transferred to DeutscheSeewarte. One of the first tasks was to find a new observatory site. The searchwas finally successful in the Lower Elbe area, on top of a terminal moraine ofthe Saale glacial period, in an area called ”Wingst”.

After the Second World War, the two above-mentioned institutions weremerged to form the Deutsches Hydrographisches Institut (German HydrographicInstitute), which was renamed Bundesamt für Seeschiffahrt und Hydrographie(Federal Maritime and Hydrographic Agency) in 1990.

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In the second half of the nineties, the Bundesamt decided to reduce thegeomagnetic service in favour of other statutory obligations. Anotherinterruption of the records appeared likely and - even worse – the observatory

| | | | | | | | F.Errulat G.Angenheister J.Bartels R.Bock | | H.Reich O.Meier |F.Burmeister M.Toperczer

Fig. 1 Photograph taken during the inauguration of WingstObservatory in 1938.

was threatened by a shutdown. Fortunately, GeoForschungsZentrum Potsdamsignalized interest and took over, but its intention is to convert the observatoryto a fully automated, remotely controlled station within a few years time.

Let us look back on the thirties: Fig. 1 shows a photograph taken in front ofthe main building on April 30, 1938, when the observatory was inaugurated.The first observer in charge, O. Meier, is shown second from the left. Next tohim, on his right side: F. Errulat, head of the new geomagnetism department inHamburg and former director of the Geophysikalische Warte Groß Raum

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(Errulat, 1974). J. Bartels can be seen in the second row (sixth from the rightside). Just two years earlier, he had become director of the newly foundedGeophysikalisches Institut Potsdam, which included the Adolf Schmidt-Observatory, Niemegk (Fanselau, 1965). H. Reich (Preußische GeologischeLandesanstatlt) is shown first from the right. He provided geological adviceconcerning the new observatory’s location (Errulat, 1939). Next to him on theright side: F. Burmeister, who had been observer in München-Bogenhausen andMaisach before and was now observer in Fürstenfeldbruck, which came intooperation at the same time as Wingst (Wienert, 1966). R. Bock (first row, thirdfrom the right) was observer at Niemegk in the early thirties. The expertise andexperience of these men contributed essentially to the successful start of the newobservatory.

One of the founding members, however, is not shown in Fig. 1: P. Maier,who was the last observer at Marineobservatorium, had been instructed totransfer the instruments from Wilhelmshaven to Wingst and to install them atthe new site. He died in 1937.

2. Instrumentation

A complete set of instruments had been specially purchased ten years earlierfor the purpose of monitoring the geomagnetic field at the old site inWilhelmshaven during the forthcoming Second International Polar Year. The setcomprised a station theodolite (No 75), an Earth inductor (No 552) and arecording system, all made by SCHULZE, Potsdam. It is worth noting that therecording system is still in operation as an invaluable stand-by in case themodern digital equipment breaks down. The excellent stability of the system,which is in no way inferior to modern devices, has been achieved by twotechnical improvements:

1. Perfecting the temperature control (by installing contact thermometers,±0.03°C) in 1956 (DHI, 1959), and

2. Replacing the Z variometer by a LA COURE type balance (sealed

against humidity) in 1966 (DHI, 1968).

The first of the above improvements paid off particularly when the second-generation suspended double system of type DMI (FGE) was installed in 1993:The base-line fluctuations have been reduced to less than 2 nT per year (Schulz,1998). The system is located on the northern pier of the variometer room (Fig. 2,

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(Errulat, 1939)). It forms the backbone of the future concept of a remotelycontrolled observatory.

Fig. 2: Plan of the variometer house, 1938 (Errulat, 1939). Anextension was constructed in 1963/64.

Since 1993: J and T: FGE double system; D: fluxgate for the Wcomponent (see text)

Digital recording had been introduced thirteen years earlier, when the first-generation fluxgate triple of type EDA (FM100C) was installed (Schulz, 1983).The reliability of the digitally acquired data has been enhanced considerably bytwo later improvements:

1 Rotation of the horizontal sensors by 45°, in 1984 (Schulz, 1S988) , and 2 Addition of a fourth fluxgate picking up the component W aligned

parallel to the triple’s spatial diagonal, in 1993 (BSH, 1998).

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Fig. 3: First PRM reading at Wingst Observatory on June 9, 1960.

These improvements are particularly useful during gaps in simultaneous Frecordings.

Let us once more look back on the thirties: To become an observatory withabsolute control, the geomagnetic horizontal intensity level was derived fromthe Niemegk standard, i.e. it was transferred to Wingst by means of a traveltheodolite. A remarkable development: Niemegk itself profited from thisprocedure a few years later, after having lost both of its standard magnets duringThe Second World War (Fanselau and Wiese, 1954). The level was successfullyrestored by re-transferring the standard from Wingst, which had not beenaffected by the war.

The proton precession magnetometer was introduced at Wingst for thecalculation of the Z base-line in 1960 (Fig. 3, see Schulz, 1988). Nelson’smethod of measuring the vertical and horizontal components followed nineyears later by means of a proton vector magnetometer of typeASKANIA/BRAUNBECK (Fig. 4), constructed by Voppel (1972). He was thesecond observer, in charge from 1954 to 1974. The instrument is still inoperation. However, in the near future, it is intended to be used as a quasi-absolute recording device for permanent remote monitoring of the base-lines, inconnection with an Overhauser magnetometer of type GEM (GSM19).

The station theodolite was replaced by a DI-flux of type ZEISS(010B)/BARTINGTON (MAG 01H) in 1992. First experiments with thisprinciple of measurement had already been carried out by MEIER and Voppel(1954) almost forty years earlier. However, the results were unsatisfactoryinsofar as the feedback current turned out to be unstable. This problem could notbe solved until the eighties.

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Fig. 4: The proton vector magnetometer of typeASKANIA/BRAUNBECK at Wingst Observatory.

3. Outlook

In this paper, a few of the activities have been described which had a directimpact on the operation of the observatory. It gives just a faint idea of theobservatory’s full range of activities in observatory-related fields (research workin the field of seafloor spreading, investigation of the North German inductionanomaly, development of transportable variographs, momentary valuecomparison between European stations since 1956, etc.). For additionalhistorical information, the reader is referred to (Voppel, 1988).

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Dehghani Spitta Nevanlinna AndersohnSchmucker Rudloff Auster Kring Lauridsen Simmons Schulz-Ohlberg Kämmerer Hegymegi Bahr Wonik Kataja Traeger Wildt Cosma Schulz Brodscholl Musmann Korschunow Barreto Green Voppel Theis Beblo Roeser

Fig. 5: Photograph taken during the 50th anniversary of WingstObservatory.

At this point, a special event should be mentioned: The 50th anniversary ofWingst Observatory, which was celebrated in 1988. To mark the occasion, aninternational colloquium was held covering "Activities of GeomagneticObservatories in the past and in the future". All papers presented during thecolloquium were published in a thematic issue of Dt. hydrogr. Z. 41, 1988, H. 3-6.

Fig. 5 again shows a photograph in front of the main building, which wastaken during the colloquium.

References

BSH, 1998: Geomagnetic results Wingst 1993. Annual Report No. 39, Hamburg and Rostock.

DHI, 1959: Ergebnisse der erdmagnetischen Beobachtungen im Observatorium Wingst in denJahren 1955 und 1956. Jahrbuch Nr. 10, Hamburg.

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DHI, 1968: Ergebnisse der erdmagnetischen Beobachtungen im Observatorium Wingst in denJahren 1965 und 1966. Jahrbuch Nr. 15 Hamburg.

Errulat, F., 1939: Das erdmagnetische Observatorium Wingst der Deutschen Seewarte. Ann. Dt.Hydr. u. Mar. Meteor., 67, 355-360.

Errulat, F., 1974: Die geophysikalische Warte Gross Raum der Universität Königsberg/Pr. – EinRückblick. Zur Geschichte der Geophysik. Springer,Berlin, 131-138.

Fanselau, G. and Wiese, H., 1954: Ergebnisse und Beobachtungen am Adolf Schmidt-Observatorium für Erdmagnetismus in Niemegk im Jahre 1951. Berlin.

Fanselau, G., 1965: Nachruf auf Julius Bartels, Gerl. Beitr. Geoph. 74, 1-6.

Meier, O. and Voppel, D., 1954: Ein Theodolit zur Messung des erdmagnetischen Feldes mit derFörstersonde als Nullfeldindikator. Dt. hydrgr. Z. 7, 73-77.

Schulz, G., 1983: Experience with a digital recording magnetometer system at Wingst Observatory(Erdmagnetisches Observatorium). Dt. hydrogr. Z. 32, 119-125.

Schulz, G., 1998: Long-term experience with digital variometer systems of different generations atWingst Observatory. Scientific Tech. Rep. 98,21, Potsdam, 27-39.

Schulz, G., 1988, The standard of Wingst Geomagnetic Observatory (ErdmagnetischesObservatorium Wingst) – its improvement and preservation, demonstrated by some examples. Dt.hydrogr. Z. 41, 119-129.

Voppel, D., 1972, The proton vector magnetometer at Wingst Observatory. Erdmagn. Jahrb. 17,Hamburg, 133-149.

Voppel, D., 1988, Some remarks on the history of Wingst Geomagnetic Observatory during thefirst 50 years. Dt. hydrogr. Z. 41, 109-117.

Wienert, K., 1966, 125 Jahre erdmagnetische Beobachtungen in München, Maisach undFürstenfeldbruck. Zum 125 jährigen Bestehen der Observatorien München – Maisach –Fürstenfeldbruck, München, 5-51