Systematic differences Astrolabe-FK5 derived from observations at zenith distance

F. Noël

doi:10.1051/aas:1997185

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Volume 124 / No 1 (July 1997)

Astron. Astrophys. Suppl. Ser., 124 1 (1997) 153-155

Abstract

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Issue		Astron. Astrophys. Suppl. Ser. Volume 124, Number 1, July 1997


Page(s)		153 - 155
DOI		https://doi.org/10.1051/aas:1997185
Published online		15 July 1997

Astron. Astrophys. Suppl. Ser. 124, 153-155 (1997)

Systematic differences Astrolabe-FK5 derived from observations at $\bf 60^{\circ}$ zenith distance

F. Noël

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

Received: 23 October 1996
Accepted: 18 November 1996

Abstract

After instrumental modifications, series of FK5 stars were observed at $\rm 60^\circ$ zenith distance with the astrolabe of Santiago, Chile, during the period 1990-1994. The mean residuals in zenith distance for each star were obtained with an average mean error of $\pm0.077''$ . Analyzing the zenith distance residuals according to the star azimuths, systematic differences Astrolabe-FK5 (J1991.9) in alpha and delta as a function of delta are derived for the zone between $-70^\circ$ and $+20^\circ$ in declination. The average mean errors are $\varepsilon_{\Delta\alpha \cos \delta} = \pm 0.003$ s and $\varepsilon_{\Delta\delta} = \pm 0.05''$ for the systematic differences in right ascension and in declination respectively. A comparison of the astrolabe results with similar ones obtained with an automatic meridian circle, is discussed.

Key words: astrometry / reference systems