Irkutsk Geomagnetic Observatory (IRT)



[edit] History

A magnetic observatory was established at Irkutsk in 1886 by the Department of National Education. Because of the increasing level of artificial noise it was moved in 1914 to Zuy, 30 km northwest of Irkutsk. Until 1960, the magnetic observatory was part of the magneto-ionospheric complex station. At present the observatory is governed by the Institute of Solar-Terrestrial Physics (formerly Siberian Institute of the Terrestrial Magnetism, Ionosphere and Radiowave propagation) of Siberian Branch of Russian Academy of Sciences. Electrification of the railway in 1958 caused the observatory to be moved to Patrony village, 20 km southeast of Irkutsk. It has an area of 2.6 hectares on the bank of the Angara river. There are main building and special pavilions for absolute and variation measurements at the observatory. Communication with the Institute is through telephone channel.

[edit] Absolute Measurements

Daily absolute measurements of the total field F and vertical component Z are made by proton magnetometer with Brownbeck's coils using a method of the horizontal component H compensation and an additional field 2*H technique. Once a week the declination measurements are taken using two fluxgate declinometers. Errors in D values are less than 0.6'. The results of absolute measurements are used to calculate basic levels of variometers which are averaged for every day with accuracy of 0.1 nT and 0.1'.

[edit] Variometers

Digital quartz variometer "Quartz-3" is used for magnetic variation measurements. It consists of three quartz sensors D, H, and Z with photoelectric converters, amplifiers, analogous filters with cut-off frequency of 0.1 Hz. Analogous signals from the sensor outputs come as two parallel flows directing for the signal analog-to-digital conversion and the digital minute data logging. The main flow is a 16-bit 8-channel ADC ADAM one with 5-s sampling rate and personal computer for digital filtration, in accordance with INTERMAGNET guidelines, and minute data recording. A backup flow has a 16-bit 6-channel ADC with 1-s sampling rate and logger. 1-s data values from ADC are averaged by the logger to obtain 1-min ones for each component.

[edit] Base Lines

Variometer base lines are determined monthly. Sensor calibration is carried out once every three months by applying sample current to feedback coil of each sensor. After calculation of sensor scale values and base level correction the array of 1-min values is edited. At the end of the year data are being checked once more, edited to eliminate results of failures, and absolute values are adopted, based on results of all absolute measurements during the year.

[edit] Archive of Results

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