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A&AS Supplement Series, Vol. 126, November II 1997, 169-176

Received September 24, 1996; accepted January 3, 1997

Absolute declinations from astrolabe data

V.A.F. Martin tex2html_wrap1514 - N.V. Leister tex2html_wrap1516

Send offprint request: V.A.F. Martin
tex2html_wrap1514  Instituto Astronômico e Geofísico, Universidade de São Paulo, CP 9638, 01065-970 São Paulo, SP, Brazil
tex2html_wrap1514  Observatoire de la Côte d'Azur/C.E.R.G.A., Avenue Copernic, F-06130 Grasse, France


We show the results of an evaluation of a global reduction method for Danjon astrolabe observations. The approach is much simpler but more precise than the conventional method. The new form of the equations gives us the possibility of using the entire set of an observational programme using the data from different catalogues taken at two zenith distances (tex2html_wrap_inline1476 and tex2html_wrap_inline1478). The observational programme contains about 15000 observations of 381 different stars taken at the "Observatório Abrahão de Moraes" (OAM, tex2html_wrap_inline1480 = tex2html_wrap_inline148200tex2html_wrap_inline148406tex2html_wrap_inline1486S; tex2html_wrap_inline1488 = tex2html_wrap_inline1490W), Valinhos, São Paulo, Brazil. The reduction was based on the FK5 system. We discuss the possibility to compute absolute declinations through the stars belonging simultaneously to the tex2html_wrap_inline1476 and tex2html_wrap_inline1478 zenith distance programmes. The absolute declination corrections were determined for 269 stars with a precision of 0.13tex2html_wrap_inline1486, and the value of the determined equator correction is 0.028tex2html_wrap_inline1486 tex2html_wrap_inline1500 0.034tex2html_wrap_inline1486. The instrumental effects were also determined.

keywords: astrometry -- astrolabe -- reference system -- fundamental stars and other objects

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