Main Project

OLP-2103-28(NN):

This project is the main project in the observatory. This project is attended by all the staff.It includes various activities like collecting the data and converting the data into digital format and then send the data to the World Data Centres and also to the other organizations located all over the world.

The purpose of the geo-magnetic measurement at an observatory is to determine the baseline values of D0, H0, and Z0 on the magnetogram, so that the values of the three recorded elements can be determined for any other time. The baselines are recorded by the fixed mirrors of the respective variometers.

Data is collected by the two systems.

Analouge (Lacour System)
Modern(Digital System)

Lacour System:

LaCour setup is based on torsion balancing the magnetic field strength.

In a classical system we are using magnetogram it is an instrument that produces a permanent

analouge record as a function of time. The record obtained is known as magnetogram.

The 3 elements recorded are H, D & Z. This System has two parts, a variometer and a Recorder.

H : In the horizontal variometer, the fibre is stiff enough to have appreciable torsion the top of the fibre is turned so that the magnet is oriented with its magnetic axis perpendicular to magnetic meridian. As H increases it winds up the fibre and as it decreases it allows the fibre to unwind.
D : The D variometer is simply a magnet suspended by a fine quartz fibre and free to rotate in a horizontal plane the fibre torsion is so small that the magnet aligns itself in the magnetic meridian This measures the changes in the magnetic element.
Z :In the Z- Variometer the magnet is povited on a knife edge. The north seeking pole of the magnet is pointing towards west any variation in the vertical field causes the magnet to oscillate. The magnet is given a field of 16,000nT as a base value.Apart from this valued variations are recorded the base mirror attached to the system light reflecting from this gives z-base line.

Working procedure for LaCour system:

The variations in the magnetic filed of the earth, deflects the magnets provided with mirrors in the variometers, reflects the light on the photo paper. This recording phenomenon gives the variations in the earth’s magnetic filed. The whole system is enclosed in a double insulated wall room in order to offset the sensitivity of magnetic moment and quartz fiber constant to temperature and humidity fluctuations.

Scanning:

The Magnetograms obtained from the La Cour System is scanned using Adobe photoshop 7.0 Version. After these Magnetograms are scanned, these Magnetograms are saved in JPEG format. Again these Magnetograms are converted into .bmp format an The conversion is done because JPEG files doesnot support WinDig software, which is used in digitization.

Digitization:

The Magnetograms are developed using the La Cour Experiment have to be digitized.

This is done with the help of WinDig software. In the WinDig software only .bmp files can be opened. So each file is opened and have to be digitized now. Digitizations are done by placing the mouse at the beginning of the trace and then press enter. After this is completed we save the file according to the date mentioned on the Magnetogram. The Hour marks are digitized by pressing the “D” button on the keyboard. Similarly all the components of all the Magnetograms are digitized.

Processing:

After the Digitization, next step is to processing the Magnetograms. The processing of Magnetograms is done with the help of Fortran programs. The processing is necessary for the following two reasons:

In order to rectify the errors (if any) occurred at the time of digitization.
The data, after the processing, is stored in a single file.

For the analysis of daily variations for baseline determinations we are doing absolute experiments

QHM : It is an absolute instrument used for measuring absolute value of horizontal component (H) of the Earth’s magnetic Field.
Principle: If a magnet is suspended freely and gives the magnet will take up an equlibruium position when the magnetic couple is equal to torsion couple.
DIM: It is a fluxgate magnetometer which is used for the measuring Declination D and Inclination I elements of Magnetic Field.

Principle: The sensing coils are mounted on the theodolite (vertical and horizontal angle, it is heart of magnetometer) They produce electrical signal , the amplitude of which is propotion to the component of Magnetic field along the axis of fluxgate coil. DIM contains circuitary which amplifies this fluxgate signal and converts it sothat is causes a metetr deflection propotional to the component of Total Magnetic Filed ( F) along the axis of fluxgate coil.(Here Sensor finds Intensity and Theodolite finds Angle’D’).
PPM: It is based on the precession of the spinning of proton when placed in a Magnetic Field and disturbed temporarily.

different variations on the magnetogram >>