The Magnetic

Observatory of Coimbra (COI): Operating Status and Future


Ribeiro, P. (1), Pais, A. (1, 2), Morozova,

A. (1)


Geophysical and Astronomical Observatory, University of Coimbra,

Portugal; (2) Department of Physics, University of Coimbra,



The Magnetic Observatory of Coimbra (COI) was

founded in 1864. Currently operated by the Geophysical and

Astronomical Observatory of University of Coimbra, is one of the

oldest observatories in operation in the world and the only one in

Portugal mainland. Due to the increasing urbanization during the first

quarter of the 20th century, the observatory was relocated to its

current site (Alto da Baleia) in 1932. The first years in Alto da

Baleia suffered from very flawed operation and all observations ended

up being interrupted around 1941 due to the difficult years of World

War. Magnetic observatory routines were resumed nearly the end of 1951

on a methodical and more accurate basis. By the late 1980s, the COI

data began showing again some non-negligible perturbations mainly

related to the aging and drift of instruments. Part of these problems

and limitations were overcome in 2007 by replacing the complete old

set of instruments with a modern digital fluxgate variometer (a DMI

model FGE, suspended version) and a standard pair of absolute

instruments (a DI-flux based on a Bartington fluxgate MAG01H sensor

mounted on a MG2KP Theodolite and an Overhauser GSM-90F1 scalar

magnetometer). This upgrading resulted in a healthier base-line

stability and in a clear quality improvement of the monthly and annual

data series as demonstrated by the lowering variance of their first

time-differences. Nonetheless, the ongoing city growth continued to

critically threaten the good functioning and quality of observatory

data, in particular the high frequency signal; which can be a

limitation for some Space Weather studies.

Besides giving a brief account of its long history, instruments and

routines, this presentation aims to characterize the geomagnetic

series currently observed in COI, and to present its master plans for

future development, which will comprise a new relocation of the

observatory to a rural area near Coimbra, and the application to

integrate the INTERMAGNET network. The presentation of some

preliminary results of the geophysical studies necessary for the

evaluation of the new site (i.e. magnetic surveys, electrical

resistivity profiles and continuous recording of the geomagnetic field

simultaneously in different points) is also expected.


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