LISN Magnetometer in Argentina
Por  Oscar Veliz

Ubicación geográfica del Complejo Astronómico El Leoncito Picture 1. Geographical location of the Astronomical Complex El Leoncito
Under a cooperation agreement between the IGP and the Astronomical Complex El Leoncito (CASLEO), it was installed the second magnetometer which has been built at Jicamarca Radio Observatory (JRO) for LISN project.

CASLEO was formally established in May 1983 as a center that provides services to the astronomical community. It is located in Calingasta, San Juan (Argentina), about 40 km. from Barreal town and it is in front of a geological structure named Barreal Blanco. The settlement of the telescope is at 2552 m above sea level, in the western foothills of the Tontal chain which separates the site from San Juan city. Province Law 5441 protects the quality of the sky since 1993, and the Astronomical Reserve is protected by the National Park Service. The geographical location of the observatory is shown in Picture. 1.

The magnetometer is composed of a three-axes fluxgate sensor (XYZ), with a resolution of 0.1nT, full range + / - 60000nT, accuracy 1nT and stability in time of +/-5nT/Year. The control unit contains the filters circuits, cancellation and amplification using 4 layer printed circuit boards, designed at JRO. This unit also includes the acquisition system based on a high-resolution data logger (20-bit), 8 outputs channels type USB to be connected to any computer or personal computer. The software includes the acquisition and transferring file program via FTP. The function of this program (ROJ_FTP) is to save one minute of data into the ROJ server, and then the magnetograms are showed through a graphical web interface.

Panoramic view of the CASLEO facilities. In the background, the main building of the telescope; on the right, the accommodation facilities and at the left side, the white hut where the magnetometer LISN has been installed. The Andes can be seen in the background of the photo, which is on the border with Chile Picture 2. Panoramic view of the CASLEO facilities. In the background, the main building of the telescope; on the right, the accommodation facilities and at the left side, the white hut where the magnetometer LISN has been installed. The Andes can be seen in the background of the photo, which is on the border with Chile.

View of the magnetometer concrete base during the procedure of orientation and leveling of the sensor Picture 3. View of the magnetometer concrete base during the procedure of orientation and leveling of the sensor

The magnetometer system began to operate on September 12th and is sending magnetogram data to the JRO server in real time, every minute. The data can be viewed via the website at:
http://jro.igp.gob.pe/lisn/data/stations/stations.php?site=leo

View of the hut’s interior where the magnetometer and the Linux PC acquisition can be appreciated; this PC also serves as data acquisition equipment for LISN GPS Picture 4.View of the hut’s interior where the magnetometer and the Linux PC acquisition can be appreciated; this PC also serves as data acquisition equipment for LISN GPS

Absolute observations

During the magnetometer installation, it has been made absolute observations on the base of the sensor, using a theodolite magnetometer DI-Flux for observations of: Declination (D) and inclination (I). Also, a proton magnetometer was used for observations of the total intensity (F), provided by the Universidad Nacional de La Plata (UNLP). An average of the results is shown in Table 1

Result of the absolute observations made on 11-12 September 2008 based on the magnetic sensor LISN.</div>
</center> Table 1.Result of the absolute observations made on 11-12 September 2008 based on the magnetic sensor LISN.

This work was supported by the staff of The Astronomical Complex "El Leoncito", especially Jose Luis Aballay and Marta Mosert from CASLEO, and Mauricio Gende from the La Plata National University.