History

The Istanbul Astronomical and Meteorological Observatory was relocated from the city center to Kandilli in 1911. At Kandilli, the first magnetic observations were made by the director of the observatory, Fatin Gökmen, on March 12, 1927, using a Chasselon-Brunner magnetic theodolite and an inclinometer acquired from France. Subsequent observations were carried out by Osman Sipahioğlu between 1936 and 1947. However, systematic magnetic observations began after 1947. While Europe was recovering from the scars of World War II, the Turkish government provided financial support to establish a serious magnetic observatory. Sipahioğlu was the first director. The results were presented at the IUGG meeting in Oslo in 1948. The chair of this meeting later wrote: "It is a great pleasure to receive such excellent results from a region where systematic measurements are so needed." Julius Bartels also made similar praises and encouraging remarks.

Kandilli is located 15 kilometers from the city center, on the Asian side of the Bosphorus, on a wooded hill with a magnificent view of both sides of the Bosphorus. The 36-hectare land, which has been the campus of Boğaziçi University since 1981, houses geophysical and astronomical disciplines. The three main magnetic structures are the variometer building, the absolute measurement building, and the office building.

The variometer building, with a copper roof, measures 14 meters by 10 meters. The walls are made of local stones and rise 2 meters above ground and descend 5 meters underground. The wall thickness ranges from 0.5 meters to 2 meters. Inside, there are two wooden chambers, both located underground. Each chamber is 4.5 meters wide, 7 meters long, and 3 meters high. They are 1.5 meters apart, and a 1-meter corridor surrounds them. There is a 2-meter gap above and below the chambers. In one room, there is the Askania Eschenhagen system with photographic recording equipment, and in the other, until recently, there were spare La Cours. The offices are located in a two-story, newly restored Ottoman-style building, 50 meters away from the observation sites. There is also a paleomagnetism laboratory and a stone-cutting room. The absolute measurement building, located 11 meters to the north, has a copper roof and is made of wood. It measures 10 by 12 meters and is 4 meters high. Over the years, absolute measurement instruments have changed, but Askania earth-inductors, BMZ63, and QHM 169 and 171 are still present. Additionally, ELSEC PVM (H and Z) and the original Askania (Schmidt-large size) declinometer (D) were used until recently.

In 1947, the population of Istanbul was 1 million, and Kandilli was outside the city. However, today, the population has reached 12 million, and the city has surrounded Kandilli. The large and protected area of the observatory has so far prevented magnetic data from becoming contaminated. In the future, the magnetic observatory may be relocated to a new site near İznik (approximately 100 kilometers southeast of its current location). This region is geophysically important as it is located in a seismic gap along the North Anatolian Fault, where there is a high probability of an earthquake. For this reason, the Institute is conducting field studies in this area. These studies include 7 continuous total field magnetometers. Additionally, 24 repeat total field measurement points have been established.

As we connected to Intermagnet on our 50th anniversary, we replaced the La Cour variometers with two 3-component EDA fluxgate magnetometers (one of which may be transferred to İznik in the future). Stability tests of these devices are currently underway, and the data are being compared with the old Eschenhagen photographic records. Also, in our 50th anniversary year, the entire data archive was digitized, and all hourly mean values were transferred to digital format. This database covers the years from 1949 to 1996, as the data for the first two years were deemed unreliable. The annual bulletins, whose publication was halted after 1980, were resumed in 1992.

The Istanbul-Kandilli Magnetic Observatory proudly looks back on its 50-year history and looks forward to the future with hope.

Stuart R.C. Malin and A. Mete Işıkara

-1997-