EDP Sciences
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Volume 375, Number 2, August IV 2001
Page(s) 614 - 616
Section The Sun
DOI http://dx.doi.org/10.1051/0004-6361:20010700

A&A 375, 614-616 (2001)
DOI: 10.1051/0004-6361:20010700

Astrometric observations of the Sun at Santiago: 1998-2000

F. Noël

Departamento de Astronomía, Universidad de Chile, Casilla 36-D, Santiago, Chile

(Received 20 February 2001 / Accepted 23 April 2001 )

A program of solar astrometry with a modified Danjon astrolabe has been in progress since 1990 at the National Astronomical Observatory at Cerro Calán, Santiago, Chile. More than 3200 homogeneous observations have been made visually by a single observer at $30\degr$ and $60\degr$ zenith distances. Here we present and discuss the results in right ascension, parameter Y and apparent solar radius obtained during the period 1998-2000. These results and those obtained in former years are available in electronic form. After almost 11 years of continuous observations, the most interesting aspect of the solar results of the Santiago astrolabe is a significant and positive correlation between variations in time of the apparent semidiameter of the Sun and solar activity.

Key words: astrometry -- Sun: activity -- Sun: fundamental parameters

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